Human Gene Therapy

December 1984

NTIS order #PB85-206076 “Where two principles really do meet which cannot be reconciled with one another, then each man declares the other a fool and heretic. ” –Ludwig Wittgenstein, 1950-1951

“Even in the extreme case where disagreement extends irreducibly to ultimate moral ends, the proper counsel is not one of pluralistic tolerance . . . We can still call the good good and the bad bad, and hope . . . that these epithets may work their emotive weal.” “Thus we do what we can with our ultimate values, but we have to deplore the irreparable lack of the empirical checkpoints that are the solace of the scientist. Loose ends are untidy at best, and disturbingly so when the ultimate good is at stake.” —Willard Van Orman Quine, 1981

Recommended Citation: Human Gene Therapy—A Background Paper (Washington, DC: U.S. Congress, Office of Technology Assessment, OTA-BP-BA-32, December 1984.

Library of Congress Catalog Card Number 84-601155

For sale by the Superintendent of Documents U.S. Government Printing Office, Washington, DC 20402 Preface

This background paper is the fourth in a series of OTA publications on genetics, and the third in a series focusing on emerging biological technologies. * It was prepared at the request of Representative Albert Gore, Jr., as Chairman of the Subcommittee on Investigations and Oversight of the Committee on Science and Technology, U.S. House of Representatives. Preparation of the paper involved extensive assistance from and review by experts and other interested parties (apps. C and D), and included a workshop convened at OTA on September 25, 1984. Interest in human applications of recombinant DNA technology has been expressed by numerous scientific, medical, religious, civic, and government leaders by Represent- ative Gore’s subcommittee and resulted in congressional hearings in November 1982, Human gene therapy is currently preeminent among the the topics of concern. This paper focuses on the imminent development of human gene therapy, emphasizing early medical applications. The governmental concerns related to human gene therapy, as for other medical technologies, will include protection of subjects involved in research and clinical treatment, ensuring safety and efficacy of the techniques in specific applications, and public discussion and education. Human gene therapy, if it is approved for use, will first be performed on patients who have no better prospect for treatment, and who suffer from severe, rapidly fatal diseases caused by defective genes. Treatment will involve inserting copies of the normal gene into cells where the new gene can be used to produce proteins that correct a biochemical defect. Human gene therapy as currently envisioned would thus be applied to treat patients with specific rare genetic diseases, and not as the tool of a eugenic social program intended to improve the human gene pool. Gene therapy in humans will first be done in cells from an organ or tissue other than germ cells, probably from a patient’s bone marrow. Such treatment would therefore not lead to heritable changes. Therefore, because cells that are used in reproduction are not involved, gene therapy of this type is quite similar to other kinds of medical therapy, and does not pose new kinds of risks. When considering gene therapy that does not result in inherited change, the factor that most distinguishes it from other medical technologies is its conspicuousness in the public eye; otherwise it can be viewed as simply another tool to help individuals overcome an illness. Public interest in gene therapy suggests that utmost care must be taken to ensure that the process for approving its early application is fair, open, and thorough. Several Federal agencies, including the Recombinant DNA Advisory Committee at the National Institutes of Health and the Food and Drug Administration, are presently involved in just this process. It is generally agreed that gene therapy that affects only the patient is analogous to other medical technologies. There is, however, no agreement about the need, technical feasibility, or ethical acceptability of gene therapy that leads to inherited changes. Commencement of gene therapy that would involve inherited changes should not proceed without substantial further evaluation and public discussion.

*The other OTA publications on genetics are Impacts of Applied Genetics (April 1981), The Role of Genetic Testing in the Prevention of Occupational Disease (April 1983), and Commercial Biotechnology: An International Ana&sis (Janu- ary 1984). The other publications on novel biological technologies are Impacts of Applied Genetics and Impacts of ~Veuro- science (March 1984).

///. . . Advisory Panel for OTA Workshop on Human Gene Therapy, Sept. 25, 1984

LeRoy Walters, Chairman, Director, Center for Bioethics Kennedy Institute of Ethics, Georgetown University

Non-Government Panelists Carol Struckmeyer Genetic Associate and Program Coordinator Lori Andrews New Hampshire Genetic Services Program American Bar Foundation Government Panelists James E. Bowman Professor of Pathology and Medicine, and W. French Anderson Committee on Genetics Chief, Laboratory of Molecular Hematology University of Chicago National Heart, Lung, and Blood Institute C. Thomas Caskey John C. Fletcher Howard Hughes Institute Medical Investigator Assistant for Bioethics and Professor of Medicine Warren G. Magnuson Clinical Center Baylor College of Medicine National Institutes of Health Theodore Friedmann Elaine Esber Professor of Pediatrics Director, Office of Biologics Research and School of Medicine Review University of California, San Diego Food and Drug Administration Ola Huntley Judith A. Johnson Board of Directors Analyst in Life Sciences Sickle Cell Self-Help Science Policy Research Division Congressional Research Service Horace Judson Library of Congress Henry R. Luce Professor Writing Seminars Henry Miller Johns Hopkins University Medical Officer National Center for Drugs and Biologics J. Robert Nelson Food and Drug Administration Professor of Theology Boston University Robert Nicholas Staff Director Nanette Newell Subcommittee on Investigations and Oversight Calgene, Inc. Committee on Science and Technology Albert Rosenfeld U.S. House of Representatives Consultant on Future Programs March of Dimes Seymour Siegel Ralph Simon Professor of Ethics and Theology Jewish Theological Seminary of America, and Executive Director U.S. Holocaust Memorial Council

iv OTA Project Staff for Human Gene Therapy

Roger C. Herdman, Assistant Director, OTA Health and Life Sciences Division

Gretchen S. Kolsrud, Biological Applications Program Manager

Robert M. Cook-Deegan, Study Director, Senior Analyst Teresa Schwab,1 Research Analyst L. Val Giddings,l Analyst Nanette Newell,2 Senior Analyst Eleanor Pitts,3 Research Assistant Stephen K. Eckman, 4 1984 Wharton Public Policy Fellow

Contractor Lawrence Wissow, Johns Hopkins University

Support Staff Sharon Smith, ’ Administrative Assistant Elma Rubright,3 Administrative Assistant Linda Ray ford, Word Processing Specialist

ISince September 1984 ‘Until April 1984. 3LJntil August 1984 4June to August 1984 Contents

Page WHY IS CONGRESS INTERESTED IN HUMAN GENE THERAPY NOW? ...... 2 History ...... , ...... 3 Concern Among Religious Leaders ...... 4

OTA INVOLVEMENT AND REVIEW PROCESS ...... 5

TYPES OF GENE THERAPY ...... 5 Different Mechanisms of Gene Therapy...... 5 Somatic Versus Germ Line Gene Therapy ...... 6 Stages of Development of Gene Therapy Technology ...... 10

TECHNIQUES OF GENE THERAPY ...... 11 Genes Are Copied and Passed on by DNA Replication ...... 11 Isolation and Cloning of the Normal Gene ...... 11 Insertion into Human Cells ...... 11

BACKGROUND ON GENETIC DISEASES ...... 13 Chromosomes and Inheritance ...... 13 Single Gene, Multigene, and Environmentally Modified Traits ...... 13 Genetic Treatment Versus Eugenics ...... 16

MEDICAL ASPECTS OF GENE THERAPY ...... 17 Genetic Corrections of Animals and Other Organisms...... 17 Reasons Genetic Diseases Cannot be Eliminated ., , ..., ..., ., ...... , ...... 18 Types of Genetic Disease That Are Poor Candidates for Gene Therapy Now ...... 20 Reasons Germ Line Therapy May Be Unnecessary...... 21 Criteria for Beginning Human Gene Therapy ...... 22

ISSUES THAT MAY ARISE FROM CLINICAL APPLICATION ...... 27 Medical Malpractice ...... 27 Parental Responsibilities ...... 27 Patents and Trade Secrets ...... 28 Insurance ...... 28

SOCIAL IMPLICATIONS OF GENE THERAPY...... 28 Background ...... 28 Major Social Issues ...... , ...... 29

THE FEDERAL ROLE IN GENE THERAPY ...... 34 International Interests in Human Gene Therapy...... 35 Federal Agencies Potentially Involved in Gene Therapy ...... 35 Functions of the Federal Government ...... 37 Case Histories...... 42

CONCLUSION...... 47

TECHNICAL NOTE 1 DNA Function . . . . , ...... , ...... 48

TECHNICAL NOTE 2 Genetic Engineering Techniques: Cloning and Vectors ...... 51

TECHNICAL NOTE 3 Violating Species Barriers ...... 52 Contents—continued

TECHNICAL NOTE 4 Page Fertilization, Implantation, and Development ...... 53

TECHNICAL NOTE 5 Hemoglobin Disorders: A Case Study of Genetic Disease ...... 57 Sickle Cell Anemia...... 57 Thalassemias ...... 58 Other Unstable Hemoglobins ...... 58 Diagnosis of Hemoglobinopathies ...... 59 Treatment of Hemoglobinopathies ...... 59

APPENDIX A–DIAGNOSTIC TECHNOLOGIES FOR GENETIC DISEASES ...... 63 Fetal Imaging ...... 63 Technologies for Fetal Tissue Sampling ...... 64 Tissue and Fluid Analysis ...... 65

APPENDIX B—PRIVACY AND CONTROL OF GENETIC PATIENT DATA ...... 69 Introduction ...... 69 Privacy and Access ...... 71 Third Party Access ...... 73

CONCLUSION ...... 79

APPENDIX C–WORKING GROUP ON HUMAN GENE THERAPY, RECOMBINANT DNA ADVISORY COMMITTEE, NATIONAL INSTITUTES OF HEALTH ...... 80

APPENDIX D–ACKNOWLEDGEMENTS ...... 81

APPENDIX E–LIST OF ABBREVIATIONS AND GLOSSARY ...... 82 Glossary ...... 83

APPENDIX F–REFERENCES ...... 91

. . . Vlll HUMAN GENE THERAPY

Advances in molecular biology have triggered lihood, combined with the lack of inheritance an unprecedented expansion of knowledge about of anticipated genetic alterations, suggests human genetics. The rise of new genetic technol- that decisions to proceed will not lead to ir- ogies, and their implied power, has engendered reversible population effects. concerns among religious, scientific, and civic Inherited alterations, the most controversial leaders that these new technologies may be grow- potential applications of gene therapy, are ing more rapidly than our ability to prudently unlikely to be undertaken in humans in the control and productively use them. The ability to near future because they are technically too insert human genes into human patients to treat difficult, are perceived as ethically prob- specific genetic diseases–human gene therapy– lematic, and may not prove superior to ex- has been one of the concerns noted by those ob- isting technologies. serving the evolution of genetic technologies.l There is a regulatory framework already in place for considering the first applications of Human gene therapy will first be considered human gene therapy. The existence of estab- in a clinical situation where it might be possible lished procedures cannot guarantee that they to treat with a human gene an individual patient will be followed, because some scientists or suffering from a genetic disease. Gene therapy physicians may choose to deviate from them, would be attempted only when there is no other but there are laws in place that can be en- therapeutic alternative, or when the alternatives forced. The existence of such a regulatory are judged to be of greater risk or less potential framework distinguishes gene therapy from benefit. Application of gene therapy for a human many other novel biological technologies. genetic disease should require evidence that it is safe, might prove beneficial, is technically possi- The primary justification for attempting human ble, and is ethically acceptable. Judgments should gene therapy is the number and severity of be made in a procedurally sound and objective genetic diseases. There are 2,000 to 3)000 known regulatory framework. genetic diseases—i.e., diseases whose roots can be traced to specific genes or known inheritance Some of the concern about the potential abuse patterns (McKusick, 1983), As many as 2 percent of gene therapy may be allayed by considering of newborn infants suffer from a genetic disease the following points: (Lubs, 1977). For most such diseases, the defec- The most promising prospects for human tive genes have not been identified or located. For gene therapy involve treatment of specific several, including some of the most severe child- genetic diseases by methods that are not de- hood diseases, the gene that causes the disease signed to cause inherited changes, and the has been found, and for a few such diseases, ethical concerns may thus be similar to those copies of the normal gene are available through associated with other medical technologies, use of recombinant DNA technology. Human gene such as vaccination or drug administration, therapy will be feasible only for those diseases currently in use (President’s Commission, in which the defect has been identified and the 1983; Shinn, 1982; Fletcher, 1982, 1983; normal gene has been isolated and cloned. All of Siegel, 1982, 1983). the diseases presently under consideration for The capability for human gene therapy will gene therapy are rare. almost certainly develop in small increments, Gene transfer experiments in animals have pro- like other medical technologies. This like- duced some inherited changes, but the ethical ‘The ckwlopment of recombinant DNA and other adk’anced tech- questions and relative inefficiency of current techniques of molecular biolo~l’ have permitted no~’el applications of niques preclude application to humans. Because I)iological methods in industry and health care through the new most of the serious concerns that human gene biotechnology. This background paper is not about industrial or medical applications of biotechnolo~~’, but rather about cleliheratd]r therapy might cause long-term changes in human changing genetic information in humans. populations presume inheritance of characteris-

1 —

2 Human Gene Therapy—Background Paper

tics, the present state of the technology does not Gene therapy, as defined here, would not in- pose fundamentally new ethical problems. Human clude genetically enhancing general characteris- gene therapy that does lead to inherited changes, tics such as behavior, intelligence, or physical however, would likely incite deep-seated appre- appearance. These are excluded from the defini- hensions about premature application. There tion, although the prospects for influencing such should be ample opportunity for public discus- traits in the population through genetic methods sion before germ line gene therapy is tested in are discussed in some sections because concern humans. The body of this background paper will about such prospects has been raised in public explicate these statements by surveying the tech- debate (Subcommittee on Investigations and Over- nical prospects for human gene therapy and dis- sight, 1982; Siegel, 1983; Rifkin, 1983; Foundation cussing the public policy considerations. on Economic Trends, 1984; National Council of Churches, 1984; World Council of Churches, Direct genetic alterations have been successfully 1983). Enhancement of complex human traits may practiced in bacteria, yeasts, fruit flies, and some never be practical or socially accepted and it is mammals. To date, scientists have not succeeded not “therapy” for a specific disease. in applying these same techniques to correct the action of defective genes or directly to change the The definition used in this report thus focuses genome of a human being. The barriers to cor- on correction of specific genetic defects in indi- recting the genetic defects that cause a few vidual patients, except when social concerns human diseases, however, are now primarily about other applications or general issues are ex- technical, and these barriers may be overcome plicitly recognized. This background paper sum- within the next few years. There are already marizes the technical, medical, and social con- grant applications to the National Institutes of siderations that arise from consideration of genetic Health that could lead to clinical testing of human manipulation in humans and how they relate to gene therapy. Requests for permission to begin Federal policy.2 the actual clinical research that would involve humans have not, however, been received to date. —— %enetic techno]ogim that do not involve gene (Iwrap}r, including “Human gene therapy,” for the purposes of this agricultural, pharmacx~]tical, and other industrial applications, hai’e report, refers to the deliberate administration of been discussed in swreral twrlier reports issued bj the Office of Terh- no]o&v Assessment (OTA) of’ the [ 1,S Congress. Impacts of Applied genetic material into a human patient with the Genetics, issued in 1981, dealt with non-human applications of bio- intent of correcting a specific genetic defect. This technology The Role of” Genetic Te~ting in the Prww]tion of’ would include, for example, replacement of the Ocrupationa] Disease, issued in 1983, cwwed the usfl of geneti(’ sl’reening in the n orkplace; ,and Commercial Bm(wh/]()/ogt .41J In- defective gene in bone marrow cells of a child af- ternational/ and.vsis, issued in January 1984, surveyed and anal}’zed fected by genetic immune deficiency. Most dis- the commercial deleloprnent of biotechnolo@ in Japan \\’estern cussion in this background paper centers on Europe, and the Unitcxl States. Issues and topics considered in these other OTA publications are not repeated here; rather, this noninherited gene therapy because it is the type background paper explores new issues relating to gene therapj in expected to be considered soon. humans.

Why is Congress interested in human gene therapy now?

Congressional interest in human gene therapy liberate “engineering” of humans who are physi- stems from general awareness of the rapid pro- cally or intellectually “superior” is morally repug- gress in molecular genetics combined with con- nant or politically dangerous, and there is fear cern about the potential power and impact of new that the new techniques might be used to attempt biological technologies. Some believe that the de- such engineering (Rifkin, 1983; Foundation on Why is Congress Interested in Human Gene Therapy Now? 3

Economic Trends, 1984). Human gene therapy for a living organism. The second patent was that leads to inherited changes, in particular, has issued for the technique of making certain types been identified as a “fundamental concern for the of recombinant DNA molecules.4 protection of the integrity, value, and health of Wall Street responded to the promise of bio- human life, both of individuals and of large num- technology in 1981 by setting a record for the bers. The putative possibility of performing germ fastest price-per-share increase when Genentech’s line therapy, however noble in intention, would initial public offering of stock rose from $35 to incur risks of unknown magnitude to future pro- $89 per share in 20 minutes. Optimism was again geny” (Nelson, 1984b). Several events contribut- noted in 1982 when Cetus made a large and suc- ing to the public interest in molecular genetics cessful initial public offering ($115 million). Early are of particular interest. commercial expectations were encouraged when the first commercial product using recombinant History DNA technology was introduced to the market In 1972, scientists joined DNA fragments from in 1982: human insulin, sold as Humulin (Office two species, resulting in the first deliberately cre- of Technology Assessment, 1984, ch. 4). Many of ated recombinant DNA molecule (rDNA) (see the expectations of rapid economic bonanza have Technical Notes 1 and 2 for further details). In been tempered by the length of time and magni- 1973, rDNA molecules were first duplicated and tude of effort required to bring products to the grown in bacteria. Concern about the safety of market, but long-term prospects for commercial recombinant DNA laboratory research led scien- applications of biotechnology remain promising tists to call for a worldwide moratorium on cer- (Office of Technology Assessment, 1984). tain types of experiments. Several scientific and Developments in regulation, law, and finance political meetings, some of them quite conten- were attended by continued advances in genetic tious, were held that focused on issues of safety research. The surprising discovery of “split” genes (Wade, 1984). In 1974, the Recombinant DNA occurred through the use of recombinant DNA Advisory Committee (RAC) was formed to advise technologies in 1977.5 That same year, two inde- the National Institutes of Health in formulating pendent techniques were developed for determin- guidelines for research; the first guidelines were ing the DNA sequences that contain genetic in- issued in 1976 (Milewski, 1984). formation, permitting direct inspection of the Commercial interest in biotechnology became genetic material and analysis of its functions (Wat- evident in 1976 when the first new firm, Genen- son, 1984). tech, was established specifically to apply recom- Advances in medical applications also occurred. binant DNA technology to medicine and other Recombinant DNA techniques were first used for areas. Since that time, more than 200 firms have the prenatal detection of sickle cell disease in 1982 been founded to exploit the new technologies (Of- (Chang and Kan, 1982; Orkin, Little and Kazazian, fice of Technology Assessment, 1984). Two pat- 1982). Use of enzymes that specifically cut DNA, ent decisions in 1980 highlighted the commercial in combination with probes that detect specific potential of new biological technologies. In one, — a bacterial strain was patented that had been de- 4This patent was granted to Stanlej’ Cohen of Stanford t “ni\er- veloped using traditional methods of selecting for sity and Herbert Boyer of the [University of California at San F’ran - cisco for the basic process of constructing recombinant DNA genetic traits, and without resort to recombinant molecules. The patent is questioned by some, but has not been seri- DNA technology.3 This was the first patent issued ously challenged at the time this is written (Office of ‘J’echnology Assessment, 1984, ch, 16). The patent has since been complemented 7’I’he first patent for a microorganism w as granted to ,Ananda by a process patent for the same technolo~k that was granted in Chakrabart}’ of the General Electric Corp. for a strain of August 1984. I%whmmas bactwiom [hat di#%ts certain petrochemicals. Dr ‘Scientists confirmed [heir expectations that the genes were more Chakrabartj dcn’eloped the strain by growing rare and mutant forms complicated in higher animals rompared to bacteria. Genes in higher of the barteria in new artificial eni’ironments until a strain u’ith organisms are often dikided into regions: the sequence for a pro- the desired chararterlstics resulted. ‘J’he dwision to grant the pat- tein, for example, may be separated into several units, and the units ent was made hjr the [ T S Suprww (:ourt in a 5 to 4 ~rotf’ on June must be rearranged and “spliced” together to form the sequence lo, 1980 that is e~entually used to produce the protein (Leder, 1978), 4 Ž Human Gene Therapy—Background Paper sequences of DNA, led to development of a method Concern among religious leaders for determining the location of genes, even when their function had not been determined and the Increasing commercial interest, progressive genes had not been isolated (Botstein, 1980; Bot- movement of the technology into the relatively stein, 1984). The technique, first described in unregulated private sector, possible premature 1980, has great promise for both promoting un- applications to humans, and impressive technical derstanding of human genetics and assisting in improvements all attracted attention to molecular the diagnosis of hereditary diseases (see app. A). genetics in the early 1980s. The general secre- In 1980, the first inherited alteration of genes in taries of three large religious bodies—the U.S. the germ line of mice was achieved (Gordon and Catholic Conference, the Synagogue Council of Ruddle, 1981) and in 1982, the gene for rat growth America, and the National Council of Churches— hormone was introduced into mice (Palmiter, sent a letter to President Carter in 1980 in which 1982, 1983). The mice that incorporated the rat they expressed concern that prowess might sur- growth hormone genes into their cells could be pass prudence in the human application of genetic induced, using a special diet containing zinc, to technologies. They noted that we had entered an grow to twice normal size. The response to zinc “era of fundamental danger triggered by the rapid was due to a special DNA sequence that the scien- growth of genetic engineering)” and appealed to tists had included with the growth hormone gene the President to look into how molecular genetics that caused zinc to “turn on” the inserted gene. might be applied to humans (President’s Commis- The progeny of the genetically altered mice also sion, 1982, pp. 95-96). The letter noted that there inherited the new foreign gene, making them was no governmental agency or committee in- “mighty mice” as well. vestigating the ethical, social, and religious questions raised by the new technologies. Such ques- The human experiments of Martin Cline, a phy- tions included concern for fair distribution of sician from the University of California at Los risks and benefits, control of genetic experimen- Angeles, contributed to the ethical apprehensions tation, and long-term consequences of genetic in- of many observers. Dr. Cline attempted gene ther- terventions. apy using recombinant DNA in two patients suffering from thalassemia, a disease causing severe The President’s Commission for the Study of anemia (see Technical Note 5)—one in Israel and Ethical Problems in Medicine and Biomedical and one in Italy. The propriety of the experiments was Behavioral Research (hereafter called the “Presi- widely questioned in the scientific literature dent’s Commission”) responded by investigating (Wade, 1980; Wade, 1981). Many scientists and some uses of recombinant DNA in humans. The clinicians judged the human experiments pre- Commission’s inquiry resulted in publication of mature (Fletcher, 1982a, 1982b; Anderson, 1982) Splicing Life in November of 1982 (President’s and pointed out that Dr. Cline did not even fol- Commission, 1982). In that same month, the Sub- low the protocol that had been approved by the committee on Investigations and Oversight of the foreign human subjects review boards. He also Committee on Science and Technology, U.S. failed to wait for approval by such committees House of Representatives, held hearings for 3 days in the United States (Talbot, 1982). Professor Cline entitled Human Genetic Engineering. was penalized by the National Institutes of Health by termination of two grants, and he resigned A resolution signed by 56 religious leaders and chairmanship of his division at the University of 8 scientists and ethicists rekindled interest in California (Sun, 1981, 1982; Talbot, 1982). (Dr. human genetics when it was sent to Congress in Cline’s experiments and the dispute over their June of 1983 and introduced by Senator Mark O. propriety are described in greater detail below.) Hatfield (Congressional Record, June 10, 1983, S The history of human gene therapy thus did not 8202-8205). The resolution urged that ‘(efforts to have an auspicious start, although many scien- engineer specific genetic traits into the germ line tists and clinicians would not consider Dr. Cline’s of the human species should not be attempted” experiments bona fide attempts at human gene (reprinted in: Foundation on Economic Trends, therapy. 1984). The signatories of the resolution came from OTA involvement and review process 5 a broad spectrum of political and religious view- (Foundation on Economic Trends, 1984; Recom- points, including diverse Protestant, Roman Cath- binant DNA Advisory Committee, 1984). Delivery olic, and Jewish representatives (signatories and of the resolution, and the involvement of Rifkin resolution printed in: Recombinant DNA Advisory and many of the signers attracted media atten- Committee, 1984). The resolution was accom- tion, once again verifying the existence of public panied by a discussion paper by Jeremy Rifkin, and religious apprehensions about the rapid ad- author of Algeny and head of the Foundation on vances of genetic technologies (Harden, 1984). Economic Trends, although the discussion paper Discussions following release of the resolution was not endorsed by all signatories of the resolu- have failed to demonstrate a consensus, even tion (Nelson, 1984a; McCormick, 1984; Dorfman, among the signatories, but the document did gen- 1983). The discussion paper warned of many po- erate the wide public discussion sought by many tential abuses of intervening in human genetics who signed it (Nelson, 1984a; McCormick, 1984).

OTA involvement and review process

OTA convened a workshop in September 1984, the workshop, resulting in review by more than where potential consumers and experts in ethics, 70 ethicists, scientists, religious and civic leaders, medicine, and genetics convened to discuss the and other concerned parties. Drafts were also dis- technical feasibility and diverse implications of tributed for review at the National Institutes of human gene therapy. The panel for the workshop Health, the Food and Drug Administration, to all and other workshop participants reviewed ma- members of the Working Group on Human Gene terial prepared by OTA staff and contractors. Sev- Therapy of the Recombinant DNA Advisory Com- eral drafts of the background paper were widely mittee of the National Institutes of Health, and to circulated for external criticism before and after other government agencies.

Types of gene therapy

Human gene therapy encompasses a broad Such genetic alterations would involve insertion range of technologies and may eventually be ap- of new material that directly codes for proteins plied to a diverse group of genetic diseases. This or that affects how existing genes are expressed variety requires that several distinctions be kept by suppressing or enhancing production of par- in mind when discussing the technology. ticular proteins. Current prospects for human gene therapy do Different mechanisms of gene therapy not include either gene modification or gene sur- Gene therapy refers to the insertion of genetic gery (Anderson, 1984) because these are more material to correct a defect. Gene therapy can complex than merely adding new genes to cells, take several forms: Such complicated manipulations can now be performed, however, in some viruses, yeast, and bac- gene insertion, in which a new version of a teria, and the necessary technologies may later gene is introduced into a cell; be discovered that would permit gene surgery or gene modification, in which a gene already controlled genetic modification in animals and in place is altered; and humans. Through the remainder of this back- gene surgery, in which a particular gene is ground paper, gene therapy will refer to gene in- excised and may also be replaced by its nor- sertion, because this is the form likely to be ap- mal counterpart. plied first. The distinction is technically relevant, —— —

6 . Human Gene Therapy—Background Paper

Gene Insertion regulate the cell. Certain sequences of DNA contain information for specific proteins such as en- Another chromosome or another part of zymes, hemoglobin (the oxygen-containing pro- the same chromosome tein in red blood cells), or the variety of receptors on the cell’s surface. Stretches of DNA that con- Chromosome containing abnormal gene \ tain the information for a specific product are called genes. The DNA of the gene would not be different for somatic versus germ line therapy, although there might be different sequences added adjacent to the gene depending on how the gene would be regulated in a particular experiment or treatment. The difference between somatic and germ line therapy is which type of cell is treated with DNA. Somatic cell gene therapy is illustrated by following how physicians might attempt to correct the genetic defects that cause ADA or PNP enzyme deficiencies. ADA deficiency is caused by absence or inactivity of the enzyme adenosine .6,1. deaminase. PNP deficiency is a different disorder ,- Viral sequences or attached DNA with some clinical similarities, It is caused by Insufficient production of Increased production absence or inactivity of the purine nucleoside protein or production of of protein or phosphorylase enzyme. In ADA deficiency, the abnormal protein production of normal protein DNA in the adenosine deaminase gene is abnor- SOURCE: Office of Technology Assessment. mal, and for PNP deficiency, there is a corresponding defective PNP gene. The genetic defect is due to an incorrect DNA sequence caused by but does not significantly affect the discussion of a mutation. The mutation could be in the form public policy implications that will be addressed of errant replacement of one nucleotide by because gene modification and gene surgery do another or loss (or addition) of one or more nu- not raise moral or medical issues distinct from cleotides somewhere in the sequence. The altered those raised by gene insertion. sequence encodes an abnormal enzyme that does not function, or causes insufficient production of the normal protein. Somatic versus germ line gene therapy Because there is either not enough enzyme, or Gene therapy might be performed in either it is present in a dysfunctional form, the chemi- germ cells (sperm, egg cells, or the cells that give cal reactions mediated by ADA or PNP do not take rise to them) or in somatic cells (cells that com- place normally in the cell. This leads to accumula- prise all other body tissues). Alterations in somatic tion of some chemicals that would normally be cells do not result in inheritance of the alteration, destroyed by ADA or PNP, and a paucity of those while modification of germ cells results in changes chemicals the enzymes are responsible for mak- that could be passed on to subsequent generations ing. In the case of both ADA and PNP deficien- if the recipient patient were to have children. cies, it appears that toxic chemicals accumulate that inhibit the action of cells that are involved Genes are comprised of deoxyribonucleic acid in body defences. (DNA). DNA, in turn, is composed of long chains of molecules called nucleotides. All the genetic in- The diseases are inherited as recessive genetic formation that is inherited by a cell is encoded traits (the two diseases caused by the different by the sequence of nucleotides in its DNA (see enzyme deficiencies are slightly different, but not Technical Notes). DNA ultimately controls forma- in a sense that is relevant here), and are usually tion of all of the substances that comprise and fatal before age 2 if not treated (Kredich, 1983). OTA involvement and review process 7

Severe immune deficiencies can be treated by sented by other types of experimental therapy bone marrow transplant (Friedrich, 1984), but not such as new drugs or novel surgical techniques all patients are eligible for transplant, and the pro- (Fletcher, 1983a, 1983b; Siegel, 1982, 1983). The cedure is quite risky and costly. ADA or PNP defi- questions that need to be addressed in assessing ciency might be treated instead by somatic cell the appropriateness of treating somatic cells gene therapy: removing an affected patient’s bone include: marrow cells, inserting normal genes for the en- What is the likely impact on people’s regard zymes into them, and returning the treated cells for the sanctity of human life? (World Council to the patient where they could grow and per- of Churches, 1983; National Council of haps produce enough of the needed enzyme to Churches, 1984). degrade the toxic chemicals, thus restoring im- What are the risks of inadvertently affecting mune function. the germ line? Although the details vary, most of the diseases What are the precautions taken against de- that might be approached by gene therapy con- liberate misapplication? form to this model: they are genetic defects that What scientific data are available to suggest cause insufficient production of normal enzymes that the treatment might work to the patient’s or production of dysfunctional ones. Gene ther- benefit? apy attempts to restore enzyme function by in- How serious is the disease? What are the serting DNA to produce normal protein. realistic possibilities of benefit to the patient? What are the risks to the patient? What is Rather than treating only bone marrow or the prognosis if there is no treatment? other somatic cells, germ cells or cells of an early What are the alternative methods of treat- embryo might be treated to correct a genetic de- ment? Is gene therapy likely to be more effect. Such germ line treatment would affect all fective, less costly, safer, or otherwise more cells in the body, including both somatic cells and acceptable than available alternatives? germ line cells. In the case of ADA or PNP deficiency, germ line therapy would likely be done How safe is the procedure, based on the best available evidence? What are the data on by inserting the correct genes into an affected em- short-term effects and long-term consequences? bryo within hours of fertilization. This might lead Are patients or their surrogate decision- to presence of a normal ADA or PNP gene in all makers properly informed about the risks cells, and expression of the normal gene with pro- and benefits of the therapy? duction of a normal enzyme in the tissues where Are the side effects of the treatment revers- it would be needed to correct the immune defi- ible or treatable in the patient and in the ciency. population? In somatic cell therapy, treatment affects only These concerns are analogous to those that cells in the patients’ organs and would not be would be raised for any other new medical treat- passed on to children, while germ line correction ment. The likelihood of inadvertently affecting the would produce genetic changes that could be germ line, however, is of greater concern for gene detected in all cells in the body and could be therapy than for most other treatments. The risk passed on to children. of genetically altering the germ line is not unique to gene therapy because several other medical TREATMENT OF SOMATIC CELLS practices —such as vaccination, cancer chemotherapy and radiation therapy—also carry this Many of the ethical and religious reservations risk (see “Safety” below). expressed about human gene therapy refer only to alterations that might affect the germ line to A concern for deliberate misapplication of gene produce inherited changes, In the opinion of sev- therapy derives, in part, from a historic associa- eral ethicists and religious thinkers, treatment of tion between eugenics and oppressive political somatic cells by genetic methods does not pose movements (see below). Genetic “purity” or pres- ethical problems different in kind from those pre- ervation of “superior” characteristics by genetic 8 Human Gene Therapy—Background Paper

means has been advocated by several political and ulations are elaborated further in the sections scientific groups in the past (Kevles, 1984), and below on medical and social aspects of gene some fear that gene therapy technology might be- therapy. come part of a coercive social program. The ra- tionale for gene therapy as currently contem- COMPARISON OF SOMATIC AND plated–insertion of single genes to correct severely GERM CELL GENE THERAPY debilitating specific genetic diseases (Anderson, There are several technical and practical advan- 1984)—is extremely remote from such eugenic tages to performing gene therapy on somatic cells motivations. as opposed to germ cells. The primary advantage of somatic cell therapy is that it can be performed The question regarding the sanctity of human on individuals at any stage of development, while life is one that has been addressed by religious germ line therapy as currently envisioned would thinkers and philosophers (Siegel, 1982, 1983; have to be performed early in embryonic devel- President’s Commission, 1982). This concern for opment. Experiments on somatic cells may be human dignity underlies the great care with done on samples or parts of organs, rather than which proposals to undertake human gene ther- an entire organ, lowering the risks of failure be- apy are now being scrutinized. Such concern sug- cause a failed experiment does not cause loss of gests that public education and discussion must the organ. Experiments involving somatic cells precede and attend clinical application (Working may also be repeated in the same individual if they Group on Human Gene Therapy, 1984; President’s fail, and the reliability of the gene transfer pro- Commission, 1982; Capron, 1984a,b). cedure does not have to be as high. Somatic cell TREATMENT OF GERM CELLS gene therapy is also advantageous because it directly benefits the person to whom it is ad- If ever applied to humans, germ line therapy ministered, rather than a person (who cannot con- could be done in several ways. Such therapy could sent to therapy) who develops from a treated be directed at sperm or ova, or cells that produce embryo. them, before the germ cells join to produce a fertilized egg. It could also be targeted at the early Despite these advantages of somatic therapy, stages of development, currently practical only there are several disadvantages. Somatic cell ther- if performed within hours after fertilization, days apy may not be applicable to some disorders that before the embryo is implanted in the uterus.’ affect multiple tissues, because cells of each organ Human gene therapy affecting germ line cells would have to be altered. It may also not be ef- raises several concerns in addition to those listed fective for those tissues composed of cells that for somatic cell therapy. These have been noted do not divide, such as brain and muscle (although by religious and civic commentators (Foundation symptoms of some diseases of nerve and muscle on Economic Trends, 1984; National Council of cells might be treated by gene therapy in other Churches, 1984; President’s Commission, 1982), kinds of cells that influence brain and muscular and include: function). Which diseases and which tissues might prove refractory to gene therapy of somatic cells propagation of unpredictable effects (both will be determined only by further study of the positive and negative) into future generations, specific genetic diseases in question. diminishing genetic diversity among human populations, and There is at least one potential advantage to long-term effects of changing genetic char- heritable correction of germ line cells. Once a de- acteristics in human populations. fect were fixed, it would be less likely to plague the direct descendants of the person who devel- The different social and ethical considerations oped from the treated embryo. This would not that arise from somatic versus germ cell manip- eliminate the risk, however, because new muta- %’or further details on stages of fertilization and human cie\wlop- tions causing the same disease could spontane- ment, see Technical Notes. ously arise. OTA involvement and review process 9

TREATMENT OF SPERM, OVA, AND Gene therapy of gametes thus offers some ad- CELLS THAT PRODUCE THEM vantages in restricted applications, but it would While germ line therapy, until now, has been affect the germ line, and would not avoid the ethi- performed on early embryonic cells, it is theo- cal dilemma associated with heritability of genetic retically possible to perform it by inserting new changes. The technical prospects for such ther- genetic information into gametes (sperm, ova, or apy, however, are less promising than treatment the cells that produce them). of either early embryos or somatic cells. For both technical and ethical reasons, therefore, gametic Sperm may be difficult to genetically alter, be- gene therapy is not imminent. cause they are small, difficult to penetrate by physical or chemical manipulations, and would have to be treated in vast numbers. Millions of IN VITRO VERSUS IN VIVO sperm are usually inseminated before fertiliza- Gene therapy can theoretically be performed tion, although only one actually fertilizes the egg; either on cells that have been removed from the every sperm would have to be treated if gene body (in vitro), or on cells that are in their usual therapy were to be assured. It would be tech- place in the body (in vivo). The first attempts at nically easier to genetically alter sperm by treating human gene therapy will be performed on cells the cells that produce them because such cells are that are removed from the body, genetically larger and less difficult to manipulate. There are altered in vitro, and restored to the patient, as several complications with this strategy, however, in the example of ADA or PNP deficiencies (Ander- including the necessity to use invasive procedures son, 1984). This procedure makes the chances of to obtain testicular cells, unavailability of meth- altering the germ line of the patient quite low, ods for artificially inducing maturation of sperm, and also reduces the probability of unintentionally and uncertainty over whether genetic changes in affecting other tissues that need not be treated sperm precursors would lead to genetic correc- (Working Group on Human Gene Therapy, 1984). tion in all sperm. Substantial technological ad- Several disorders in addition to ADA and PNP vances would thus be required for reliable gene deficiencies are currently under discussion for therapy of sperm or their precursor cells. somatic cell gene therapy. Citrullinemia is caused In contrast, ova, or egg cells, might be altered by deficiency of the enzyme arginosuccinate syn- after they were extruded from the ovary, and thetase involved in protein and amino acid me- before fertilization. Egg cells are larger and more tabolism and nitrogen excretion (Walser, 1983). easily manipulated than sperm, suggesting that The gene has been isolated and cloned (Freytag, eggs might be easier candidates for gene inser- 1984), and citrullinemia is considered a promis- tion. Methods for obtaining human ova are now ing candidate for early application of human gene routinely practiced for in vitro fertilization tech- therapy. Ornithine carbamoyl transferase defi- niques, and many do not involve highly invasive ciency can be quite severe, and the gene that techniques (Andrews, 1984c). Manipulations of codes for it has been cloned (Horwich, 1984), mak- egg cells and early embryos differ primarily in ing it also a potential candidate for gene therapy. that the eggs could be altered before fertilization, Lesch-Nyhan disease is a rare genetic disorder. eliminating some ethical concerns of those who It affects primarily boys who appear normal at regard fertilization as the beginning of human life. birth but soon show abnormal uncontrollable Unless the gene therapy technique were extremely movements. Abnormal behaviors of self-mutila- reliable, however, methods would have to be tion such as biting off fingers or otherwise in- found for confirming that the desired alterations flicting painful injuries are part of the syndrome, had actually occurred. This would involve sampl- as well as aggression towards others. These ing of embryonic or fetal tissue, and would thus bizarre symptoms are extremely distressing to the not avoid all of the ethical questions that beset patient and his family. Lesch-Nyhan syndrome is embryonic manipulations. caused by complete deficiency of the enzyme

38-803 0 - 84 - 2 , QL 3 10 • Human Gene Therapy—Background Paper hypoxanthine-guanine phosphoribosyl transfer- Feasibility testing, involves animal studies and ase (HPRT), the same enzyme that is partially defi- in vitro experiments on human cells, but not cient in gout (Wilson, 1984). The gene has been with patients. cloned (Miller, 1984; Jolly, 1982; Yang, 1984), and Early clinical research involves a few human proposals for human experimentation on gene patients with rare and severe diseases for therapy for Lesch-Nyhan syndrome have been whom other treatment alternatives are too submitted to at least one local Institutional Review risky, inapplicable, or less likely to be bene- Board (Baskin, 1984; Merz, 1984). Proposals to ficial. begin human experiments on Lesch-Nyhan syn- Clinical testing will occur only if a potential drome are expected to be referred soon to the for success has been demonstrated in early National Institutes of Health (Anderson, 1984; clinical research and feasibility testing. Clin- Jenks, 1984; Merz, 1984). ical testing might involve a wider range of diseases and larger number of patients than It may be possible in the future to alter specific early clinical research if experience with tissues while they are still in the body. It would more severe diseases is fruitful. The final be desirable, for example, to selectively alter stage would be nerve cells to treat diseases caused by metabolic Standard medical practice in those specific disruption of brain cell function, or to correct instances where gene therapy has been only liver cells in genetic diseases that primarily shown safe and efficacious for a particular affect proteins produced by the liver. The worst disease or type of patient. Issues of fair ac- behavioral symptoms of Lesch-Nyhan syndrome, cess to the technology, methods of paying for for example, presumably involve disruption of it, and proper quality assurance would normal neural processes, and it might prove nec- emerge as the technology made the transi- essary to directly treat nerve cells. While meth- tion to this final stage. ods for specifically targeting particular cells for directed gene therapy are theoretically possible, Somatic cell therapy is now in the first stage, they have not yet been developed. Several possi- verging on the second. Germ line gene therapy ble methods of delivering specific genes to tar- has not even undergone feasibility testing in a geted cells may be found in the future, however, form that might be applied to humans. Gene ther- by use of tailored viruses or antibodies attached apy for different disorders or specific kinds of to artificial membrane sacs that contain the appro- patients will beat different stages of development; priate genes (see Technical Note 2). only a few diseases are now being tested for feasibility of somatic cell therapy (Working Group Stages of development of gene on Human Gene Therapy, 1984; Anderson, 1984). therapy technology

If human gene therapy becomes a viable medical technology, its development will fall into several stages. Techniques of Gene Therapy Ž 11

Techniques of gene therapy

Gene therapy involves isolating a gene, putting Once the gene that causes a disease has been it into cells where it will be used, and ensuring identified, the corresponding normal gene must that the inserted gene functions in the new cells be isolated, unless it is already available because in a way that does not harm the patient. it has been studied for some other purpose. Using an abnormal gene to find its normal counterpart Genes are copied and passed on is usually done by exploiting the extensive simi- by DNA replication larity between the sequences of the normal and defective genes; they rarely differ greatly in over- Genetic information is transmitted from one cell all sequence (although the functional results are to its progeny by duplication, or replication, of quite different, or there would be no disease). its DNA. When a cell divides, it copies its DNA After the normal gene has been identified and and distributes a copy to each of two offspring isolated, then it must be copied. The process of cells. A new therapeutic gene introduced into a making multiple copies of a single gene is called cell in the laboratory can thus be reproduced 7 cloning. Cloning involves combining the gene of through the process of cell division when the cell interest with DNA sequences that allow it to be is placed into a patient and proliferates. copied in lower organisms—usually bacteria or Many breakthroughs in molecular genetics have yeasts. The DNA containing the gene of interest come from discoveries about how DNA replicates, is then inserted into bacteria or yeast (or, more how it can be specifically cut and reassembled, recently, into some types of mammalian cells and how to re-introduce the altered DNA back growing in culture). The DNA is copied as the cells into cells in such a way that its expression, or proliferate. The numerous copies of DNA are then translation into protein, can be controlled (Jud- purified from other cell components, and the gene son, 1980). Many of the techniques for splicing of interest can be cut away from unwanted DNA and controlling the expression of genes were first sequences, One now has millions or billions of discovered between 1970 and 1974, using some copies of a single gene. of the same techniques that led to the develop- These copies are then combined with DNA that ment of recombinant DNA (Watson, 1984). is suitable for insertion into human cells. Isolation and cloning of the Insertion into human cells normal gene The DNA that contains the normal gene can be The usual first step in approaching gene ther- administered to human cells in several ways: apy is identification of the abnormal gene. (This using viruses, physically injecting it, treating the step can be skipped when the corresponding nor- DNA chemically so that cells take it up, treating mal genes are already available, as was the case the cells so that they are induced to take in the for sickle cell disease.) Once the abnormal gene DNA, or by fusing the cells with membranes that has been found, then copies of the corresponding normal gene must be isolated and copied. There T’r)r details of cloning, see the ‘1’echnica] Notes. (honing a gene are several ways to identify abnormal genes. should not be umfused with cloning an organism, ‘1’}le term “clon- These involve analysis of patterns of inheritance ing” refers to reproduction mrithout mating: in the case of a g[>nc or DNA sequence, this merely means making copies of the relrwant of a disease, study of the metabolism of patients stretch of DNA. Cloning a whole organism, in contrast, in~’ol~ws co- who have the disease, and analysis of the genes p)ring all of a cell’s DNA so that a completely new organism that of those who have the disease, Identification of shares all its genes with the original is produced. The techniques tor (loning grnes are completely’ different frum those for cloning the gene that causes a particular disease requires organisms. Cloning an indliidual human Jt’ouki not help in thr pre- hundreds of experiments, luck, and extensive re- ! ent ion of genet i(’ disease, and is not d irerth’ related to the (lues - sort to recombinant DNA technology. tions raised b~r human gent’ therap~ 12 Human Gene Therapy—Background Paper contain the DNA. In the distant future, designed alternative that is ethically unacceptable for viruses or genetic elements may be used to trans- human experiments) (Anderson, 1984). fer genes to specifically targeted human cells. At present, however, more primitive methods are used. CHEMICAL AND PHYSICAL METHODS Some early experiments in gene transfer em- VIRUSES ployed mixing DNA with chemicals and subse- Viruses are small packages of genetic informa- quently applying the DNA to a large number of tion in the form of DNA or RNA that enter cells cells. Most cells would pick up the DNA, and some and either insert their information into that of would insert it into their own DNA, and, in some the infected cell or duplicate themselves using the cases, express it. The usual chemical treatment cell’s biochemical machinery. Viruses are usually employed calcium phosphate with relatively large covered with a coat of protein or membrane, but amounts of the desired DNA. The most common their most distinguishing characteristic is the physical method involved “electroporation”) in genetic information that they contain. Some which electrical treatment of the cells induced up- viruses promise to be practical for gene transfer take of DNA and other constituents from the because they are relatively simple and controlla- fluids bathing the cells. ble, and contain sequences that permit insertion Chemical and physical treatments have the of genes into the host’s DNA. Modified viruses are advantage of not requiring a vector to cause in- the most likely candidates for gene therapy in the sertion, but have two major disadvantages. First, long run, because they are highly efficient, can the DNA is only stably incorporated into a small affect many cells, and are relatively easy to manip- proportion of cells, usually only one in ten thou- ulate in the laboratory (Rawls, 1984). sand to one in a million. (This small proportion Several scientists are developing viruses that nevertheless usually represents hundreds or would not injure cells, would not propagate un- thousands of times more cells than could be di- controllably, and would enter only target cells rectly injected.) This feature requires that cells (Anderson, 1984). Such viruses have been suc- that take up and incorporate the desired DNA cessfully used to insert new genes into blood- must somehow be separated from cells that do forming cells of mice with relatively high effi- not, and there must be a very large number of ciency (A. D. Miller, 1984; Williams, 1984). At cells to treat in the first place. Second, the DNA some point, scientists may be able to design a usually inserts at random into the cell’s genome, virus that could be used for cloning as well as de- and often in multiple copies. DATA insertion fol- livery, saving yet more steps. lowing chemical and physical insertion methods is thus relatively uncontrolled and unpredictable MICROINJECTION (Anderson, 1984). Microinjection of DNA involves putting the DNA one wants to insert into a solution that can be MEMBRANE FUSION pushed directly into individual cells through ex- The final way to get DNA into cells involves put- tremely small needles made of glass. The tech- ting it inside of membranes that can then be fused nique is highly reliable, in that a high proportion with the outer membrane of target cells, allow- of cells that receive genes express them (Capec- ing the contents to spill into the cells. The mem- chi, 1981), but limited by the number of cells that brane sacs, called liposomes, can be made of ar- can be directly injected. Investigators can inject tificially constructed lipid mixtures or derived hundreds or thousands of cells, at most, for a from specially treated cells such as red blood cells given experiment, compared to billions that can or bacteria. The advantage of cell fusion is that be treated using viruses or chemical treatments. it is relatively simple, and large numbers of cells Microinjection has been the method of choice for can be treated. It is, like chemical treatment, experiments involving gene transfer in mice, be- unreliable and nonspecific at delivery. The tech- cause of its reliability, but its applicability to nique might prove useful in the future, however, humans is questionable because it is not com- if membranes are constructed that target specific pletely reliable, and often results in cell death (an cells with highly reliable delivery. Background on Genetic Diseases 13

Background on genetic diseases

Chromosomes and inheritance ual. The relative importance of genetic and environmental influences varies in both patients and Higher organisms package their DNA into seg- diseases. Some medical conditions, such as auto- ments called chromosomes. Each chromosome is mobile accidents or war wounds, may have large composed of one very long stretch of DNA that environmental and very small genetic contribu- is bound to various proteins and other molecules. tions. Most diseases have a mixture of genetic and There are two copies of each of 22 chromosomes environmental contributions (Harsanyi, 1981). In in the cells of a human. In addition, there are two several disorders, such as Huntington or Tay- sex chromosomes. Females have two ‘(X” chromo- Sachs diseases, the influence of a single gene is somes and males have one “X” and one “Y. ” In nor- so large that the disorders are called genetic mal human cells, therefore, there are 46 chromo- diseases. somes: 2 sex chromosomes and 2 copies of each of 22 other chromosomes (these non-sex chromosomes are called autosomes). SINGLE GENE TRAITS, OR MENDELIAN TRAITS When traits or diseases are primarily deter- The 46 discrete aggregates of DNA and attached mined by a single gene, they obey the relatively protein that comprise the chromosomes are main- simple laws of inheritance first specified by tained inside the nucleus of somatic cells. In germ Gregor Mendel, a monk who lived in the last cen- cells, in contrast, a specialized phenomenon called tury and whose interests in agriculture led him meiosis takes place. Cells divide so as to leave only to discover several genetic phenomena in plants. 23 chromosomes in a sperm cell or ovum: one sex The same patterns of inheritance that Mendel first chromosome (either an “X” or a “Y”) and one copy described in plants, noted below, are also found of each of the autosomes. All ova contain an “X” in several human diseases, and thus indicate that and 22 autosomes, because they derive from the cause of the disease is genetic. female cells that contain two “X” chromosomes. Sperm are divided into two groups; half have an At the turn of the century, a British physician “X” and 22 autosomes and the other half have a and scientist, Archibald Garrod, first introduced “Y” plus 22 autosomes. the idea that some diseases that followed definite inheritance patterns might be caused by “inborn During the process of fertilization, a sperm joins with an ovum to restore the chromosome num- errors of metabolism” (Stanbury, 1983; Kevles, 1984). He postulated that some diseases were due ber to 46. If the sperm contains an “X” chromo- to biochemical errors. He further speculated that some then a female is produced, and if it contains such biochemical defects might be caused by a “Y” then a male results. genetic abnormalities that obey Mendel’s laws. Several decades later, biochemical errors were, Single gene, multigene, and for first time, traced to specific enzymes. These environmentally modified traits discoveries confirmed Garrod’s hypothesis. Other diseases were traced to molecular defects in non- Diseases that might be treated by gene therapy enzyme proteins; the first “molecular disease” de- will, at least in the foreseeable future, be ex- scribed was sickle cell anemia, in which an ab- clusively those caused by mutations in a single normal hemoglobin protein was found (Pauling, gene. Such diseases are called single gene defects, 1949). Research over the past three decades has and contrast with diseases and traits influenced revealed more and more genetic diseases, and by several genes or environmental factors. Genes greater understanding of many of them. can cause disease through several mechanisms. Most human diseases have a genetic component Many genetic diseases are due to changes in just inherited by the individual and an environmental a single gene, such as ADA and PNP deficiencies. component that comes from outside the individ- More than two hundred specific enzyme defects 14 • Human Gene Therapy—Background Paper cause known human clinical syndromes, and over Recessive Inheritance a hundred other genetic diseases have been bio- Father Mother chemically characterized (Stanbury, 1983). Prom- inent disorders such as sickle cell anemia, familial hypercholesterolemia, polycystic kidney disease, Huntington disease, neurofibromatosis, Duchenne muscular dystrophy, cystic fibrosis, achondroplasia, hemophilia, and many others are examples of single gene disorders. Many common adult disorders, usually excluded from pediatric statistics on genetic disease prevalence, such as Alz- heimer disease and hemochromatosis, have forms strongly influenced by genetics (Breitner, 1984; Cook, 1979, 1981; Folstein, 1981; Cartwright, 1978, Dadone, 1982; Skolnick, 1982; Kravitz, 1979). Single gene defects affect 1 to 2 percent of newborns (Lubs, 1977), and addition of adult genetic Non-carrier Carrier Child diseases would significantly increase the esti- 25% 50% with mated prevalence and cost of genetic disease. disease 25%

Even diseases or traits that are due to a single Chromosome with normal gene gene vary widely in severity, depending on envi- Chromosome with defective gene ronmental factors and other genes; the extent to SOURCE: Office of Technology Assessment. which patients have signs and symptoms of a genetic disease is called “expressivity.” Diseases can also be variably expressed in populations, cific defects in enzymes. However, the specific affecting some people and not others who carry molecular defect underlying many recessive dis- the gene. This is described as “penetrance.” Com- eases, including at least one common one-cystic plete penetrance indicates that all who have the fibrosis—is not known, defective gene also have the disease, while in- Dominant Disorders.--Dominant disorders oc- complete penetrance means that some people cur when offspring receive a defective gene from have the gene but not the disease. either parent, and having just one such gene leads Single gene traits can be classified by how they to expression of the disease (see diagram). In some are inherited. They can be recessive, dominant, cases the defect is known, such as some types of or X-linked. porphyria, in which enzyme deficiencies lead to abnormal disruption of biochemical pathways Recessive Disorders.--Recessive diseases occur that produce and degrade heme—the non-protein when one receives a defective gene from both part of hemoglobin found in red blood cells. In parents (see diagram). Diseases due to dysfunc- most dominant disorders, however, the biochem- tional gene pairs are usually due to protein ab- ical nature of the derangement is not known; the normalities that cause a biochemical imbalance. molecular defect in dominant disorders is, in gen- Sickle cell disease and thalassemia affect globin, eral, less well established than for recessive ones. the protein part of hemoglobin, which transports oxygen through the blood to body tissues. Other X= Linked Disorders.—X-linked disorders are recessive disorders, such as Tay-Sachs disease, carried on the “X” chromosome. X-linked diseases ADA and PNP deficiencies, and phenylketonuria usually affect boys because males have only one (PKU), affect enzymes whose absence or dysfunc- copy of the “X” chromosome: there is no set of tion adversely affects cellular metabolism. Most genes on a second “X” chromosome to balance the of the relatively well understood genetic diseases effects of a defective copy of the gene. The in- are recessive disorders that can be traced to spe- heritance pattern of X-linked disorders is distinc- Background on Genetic Diseases . 15

Dominant Inheritance from the mother in boys, and are usually reces- Affected parent Unaffected parent sive in girls. Examples of X-linked disease traits are hemophilia, Duchenne muscular dystrophy, and Lesch-Nyhan syndrome. There are apparently few traits, and no known diseases, that are carried in genes located on the “Y” chromosome, and expressed only in males. Single gene defects are, in general, the best understood of genetic diseases; the early instances of human gene therapy will be done to correct the effects of single mutant genes.

MULTIGENE TRAITS There are certain body characteristics and other traits that accrue from the interactions of several genes. Eye and hair color, for example, Unaffected Affected are traits that are specified by genes, but do not chiId child 50% 50% obey simple Mendelian patterns of inheritance because many genes are involved. Similarly, there Chromosome with normal gene are genetic diseases caused by interactions of Chromosome with defective gene multiple genes that are minimally affected by envi- SOURCE Off Ice of Technology Assessment. ronmental influences. Such disorders are termed polygenic or multigenic. X-Linked Inheritance Mother Father ENVIRONMENTALLY MODIFIED TRAITS (carrier) (unaffected) The vast majority of characteristics that define individuals are determined by a combination of genetic predisposition and interaction with the environment. Height, for example, though determined genetically to a significant extent, is also influenced by nutrition and other factors. Like- wise, many diseases derive from interactions of genes and the environment in which both components contribute significantly to the disease process. The type of diabetes mellitus that occurs in younger people, for example, is now believed to Non-carrier Carrier Affected Unaffected be caused by a special susceptibility of insulin- daughter daughter son son NOTE: x—Normal chromosome. secreting cells to certain viral infections or other @ –Chromosome with abnormal gene. environmental insults. The clinical disorder is thus SOURCE” Off Ice of Technology Assessment caused by an environmental agent acting in concert with genetic characteristics. Most common tive: sons inherit the traits only from their mothers, diseases, including cardiovascular diseases, can- because a son always derives his “X” from his cer, and many drug reactions appear to involve mother and his “Y” from his father. Daughters multiple genes as well as environmental in- can get a defective gene from either parent, but fluences. do not usually have the disease unless they get the abnormal gene from both parents. X-linked Most complex human traits, including physical traits thus act like dominant traits inherited only and intellectual capacities, are also multigenic and 16 Human Gene Therapy—Background Paper environmentally influenced. The controversies Germs of eugenic thought persist in contem- that have raged in the psychological literature porary society, notably in regard to controver- over the genetic and racial components of intel- sies about genetics and intelligence (Lewontin, ligence center on the relative importance of 1984), and some fear that the technical advances genetic and environmental contributions, includ- of molecular genetics may lend themselves to ing nutrition, health care, cultural background, abuse (Grobstein, 1984; Reilly, 1977). This is not and socioeconomic status. There is little doubt a criticism of the technology per se, but rather that genetics and environment interact, but there a concern about its potential misapplication or af- is vigorous contention about which factor pre- filiation with forms of social coercion (Powledge, dominates and how public policy should respond 1984). to differences in complex traits such as intel- The distinction between gene therapy and ligence, eugenics rests on several different points. Gene therapy involves the informed participation of pa- Genetic treatment versus eugenics tients who suffer from a specific disease, while eugenics involves social programs, sometimes in- Eugenics is the term applied to “the ‘science’ of voluntary ones, focused on general human traits. improving human stock by giving ‘the more suit- Gene therapy is intended to benefit a particular able races or strains of blood a better chance of individual, while eugenics is intended to improve prevailing speedily over the less suitable’ “ (Kevles, the human general (or, often, national) popula- 1984, quoting Francis Galton). The eugenics move- tion. Gene therapy is directed at correction of ment is noted for promulgating social programs symptoms due to genes known to cause disease, intended to enhance desired human traits, such while eugenics often dwells on polygenic traits as intelligence and physical strength, and to elim- whose genetic components are controversial, and inate undesirable traits, such as “feebleminded- whose expression is poorly understood. ness)” criminality, and disease. Medical, scientific, technical, ethical, religious, Eugenic social movements date back to the last and social commentators have noted the differ- century, and the intellectual history of eugenics ence between therapy for a specific genetic dis- extends much further back in history (Kevles, ease and interventions intended to enhance traits 1984). Deliberate eugenic interventions have been such as intelligence and physical appearance decried several times in the 20th century. Eugenic (Siegel, 1982,1983; Fletcher, 1983b; Friedmann, movements were popular throughout Europe and 1983). Genetic correction of specific diseases, if the United States early in this century, and were it does not affect the germ line, is analogous to most overtly expressed by the National Socialist other medical procedures that involve risk assess- (Nazi) Party in Germany before and during World ment by the patient and attending health profes- War II. sionals. Federal legislation to restrict immigration passed There is not a complete dichotomy, however, between World Wars I and II was based, in part, between the correction of specific diseases and on eugenic principles, and mandatory steriliza- eugenics based on social preferences for certain tion laws also supported by eugenicists still exist traits. This is relevant in considering gene ther- in several States (Kevles, 1984; Reilly, 1977) and apy because it vitiates any sharp distinction be- are occasionally used (Bowman, 1984). Many tween correction of a specific genetic defect, prominent geneticists were involved in the Amer- which might be treated by gene therapy, and ican eugenics movement in the early part of this affecting a mildly undesirable trait, for which century (Kevles, 1984), and participated as “ex- gene therapy might be controversial. A genetic perts” in preparing legislation or otherwise pro- condition might be considered serious by one per- mulgating social reform congruent with eugenic son, and not by someone else. Baldness or brown aspirations. eyes, for example, might be considered treatable Medical Aspects of Gene Therapy . 17 genetic defects by one family, and would scarcely ronmentally influenced, and thus technically ap- be noticed by another. proachable by gene therapy only in the distant future, if ever. There is no guarantee, however, The distinction between individual decisions in that it will always be impossible to use the tech- favor of gene therapy and social programs ad- niques developed for gene therapy to improve vocated by eugenicists can also blur if gene ther- socially esteemed mental or physical traits in at apy becomes commonplace. Many individual deci- least some patients. If desirable traits can be mod- sions can culminate in wide social effects. The ified by methods developed for gene therapy, social impact of gene therapy depends on how then public policy for such applications may well often it is used, who has access to it, which con- prove analogous to those now employed for cos- ditions are treated, and what public policies are metic surgery. Cosmetic surgery is not generally erected to foster or inhibit it. As long as gene ther- reimbursed as part of government or private apy is restricted to rare recessive disorders, it will health insurance, but is usually paid directly by likely have minimal social risk and large benefits individuals. Cosmetic surgery has not generated to individual patients. major public policy dilemmas, although contro- Application of gene therapy to enhance traits versy might arise in gene therapy if parents were such as intelligence or physical strength cannot attempting to secure “cosmetic” gene therapy on now be done because so little is known about the behalf of an unborn infant or young child, or to genetic influence on such traits. Most traits that authorize germ line changes that would not be some individuals might consider desirable to reversible in future generations. amplify will likely prove to be polygenic or envi-

Medical aspects of gene therapy

Early clinical experiments in human gene ther- which disorders might be approached using gene apy will be performed on somatic cells of pa- therapy in the near future. The analysis is re- tients to attempt partial correction of life-threat- stricted to the early applications of human gene ening diseases. They will be performed to allay therapy because technical predictions beyond this the signs and symptoms caused by a defect in a time horizon are perilous, and because decisions single gene whose normal counterpart has been confronting Federal policymakers in the next few cloned, and whose correction does not require years will be focused on early applications. careful control of expression. Gene therapy will be considered when there is no preferable alter- Genetic corrections of animals and native treatment available to the individual pa- other organisms tient. This prediction is based on analysis of several factors described below, and underlies the Gene therapy is contemplated in humans only analysis throughout this section. Predictions about because it has been performed in animals and human gene therapy are based, in part, on results lower organisms. One of the most successful at- of animal experiments. A short review of such tempts to genetically alter organisms involved the animal experiments is followed by a discussion “cure” of a genetic defect in fruit flies (Spradling, of relevant clinical considerations in humans. The 1983). Some fruit flies have an enzyme defect that medical aspects of gene therapy include reasons results in their having rose colored eyes. Scien- that genetic diseases can never be completely tists were able to correct this abnormality by de- eliminated from the population, why certain types livering the correct gene into fly cells by using of genetic diseases are not good candidates for DNA molecules specific to fruit flies that can carry gene therapy, why germ line therapy may never foreign DNA into the fly’s own DNA. The treated be necessary or its use extremely restricted, and flies that took up the normal gene transmitted the —

18 • Human Gene Therapy—Background Paper

genes to their progeny, who showed normal eye 1984; Williams, 1984; Anderson, 1984). These ex- color. periments used modified viruses as the gene transfer agents in ways quite similar to those that Gene transfer experiments have also been done might be used in humans, although treatment of in mice. Several traits have been artificially added the recipient mice was more drastic than may be to mouse cells early in embryonic development. acceptable for humans, and data on long-term In experiments involving transfer of rat growth risks (e. g., reversion to infectious virus type, in- hormone to mice, the mice that develop from the duction of new mutations, predisposition to can- altered embryos express the foreign genes, al- cer, and integration into the germ line) were not though not in a way that is controlled like the nor- reported. The new studies show great promise, mal gene would be. Scientists have had to use and demonstration of technical feasibility should special techniques to get mammalian cells to in- encourage animal experiments to ascertain the corporate new genes, and the genes are inserted magnitude of the risks. into chromosomal or cellular locations that cannot be predicted or controlled. Examples of genes Other recent experiments demonstrate that that have been transmitted to progeny in mice proper regulation of gene expression in the cells include the gene for rabbit hemoglobin, rat of humans and other higher animals is more com- growth hormone, and a DNA fragment with both plex than in fruit flies and bacteria. Early attempts specific enzyme activity and antibiotic resistance at gene therapy in humans will probably, there- to neomycin (Palmiter, et al., 1982; Palmiter, et fore, be conducted on diseases for which there al., 1983; Brinster, 1983; Wagner, et al., 1981; is reason to believe that precise regulation is un- Williams, et al., 1984). necessary for therapeutic benefit, such as ADA and PNP deficiencies. Early plans to apply gene The growth hormone experiment was espe- therapy to diseases in which regulation would be cially interesting because expression of the gene important have been thwarted by the complex- could be manipulated by the scientists, and this ity of regulation, although such obstacles may feature was inherited by progeny of the treated eventually be overcome. Hemoglobin disorders, mice. Other transferred genes have also been for example, will not be the first candidates for passed to the progeny, although genetic manipula- human gene therapy because of the need for reg- tions have occasionally resulted in undesired side ulation of globin expression (Anderson, 1984). effects, such as sterility or induction of new mutations. These effects suggest that oversight com- Reasons genetic diseases cannot mittees will seek evidence that such side effects be eliminated are highly improbable when inspecting proposals for experiments that involve human gene ther- There will always be patients who suffer from apy (Working Group on Human Gene Therapy, genetic diseases. It will never be possible to elim- 1984). inate even single gene defects, although the prevalence of some disorders, especially some Most of the animal experiments noted above dominant ones, could be significantly reduced. resulted in germ line changes of the treated New mutations causing genetic defects will always mouse lines, The experiments were done to in- occur, and so people will be born carrying such vestigate animal development, rather than to pave mutations. Neither would it be possible to stop the way for human application of gene therapy. the expression of recessive diseases by prevent- More recent experiments have been done on so- ing those who carry one copy of any abnormal matic cells of animals, and are more directly gene from mating, because humans carry an esti- analogous to what would be done in early human mated 5 to 10 recessive defects in their genome trials. Several groups of investigators have suc- on average, and so no one would be permitted cessfully inserted genes into the bone marrow to mate. cells of mice, and have shown production of proteins from the inserted genes in cells that derive It is already possible to prevent the birth of from bone marrow cells (Kolata, 1984c; A. D. Miller, children with some genetic disorders through Medical Aspects of Gene Therapy 19 genetic counseling, prenatal diagnosis, and family made). All those who carry the gene for Hunt- planning. The number of diseases for which this ington disease will develop the disease if they live is possible will grow as we learn more about long enough. If carriers could be told whether human genetics. It is unlikely, however, that cur- or not they had the gene before deciding to have rent methods for preventing genetic disease will children, and if all those who carry the gene prove practical for all, or even a large fraction decided not to have children, then the gene could of couples in the near future. Most genetic dis- be eliminated in a single generation. This is true orders still cannot be detected prenatally, and of Huntington disease because it is almost always tests for carriers are available for even fewer dis- inherited and only rarely due to a new mutation eases. Yet effective prevention requires such tests. (this is not true for many dominant disorders). Furthermore, such tests must not only be avail- Elimination of the gene would, however, entail able; they must also be used. Barriers to use in- large numbers of coordinated personal decisions. clude cost, complexity, and lack of public aware- Marjorie Guthrie, wife of the famous folk singer ness. Given the large number of potential genetic Woody Guthrie who was afflicted with Hunt- diseases, it is unlikely that any one screening test ington disease, posed a difficult question that will screen for all, or even most genetic diseases. bears on any program to prevent the birth of This means that for many disorders, couples will those with Huntington disease, “Does anyone only know that they are at risk after an affected really think it would have been better for Woody child has already been born. Thus, until the en- not to have come into the world-in spite of tire child-bearing population is screened for a everything?” (Cited in Rosenfeld, 1984). IS the dis- given defect, or prospective parents know of . ease so awful that the birth of potential Hun- special risks, even those diseases for which all the tington patients should be prevented when they relevant tests are available will persist. would have several decades of relatively normal It maybe useful to screen some populations for life? This is just one of several difficult dilemmas some defects. Screening programs for Tay-Sachs that emerge from advances in genetics related to carriers among Jews of Eastern European de- particular diseases. New genetic technologies for scent, and for thalassemia among Mediterranean determining the genetic makeup of humans may populations have been successful in some in- provide the information about whether one is sus- stances. These successes cannot be generalized ceptible to Huntington diseases and other dis- to all genetic diseases, however, and are probably orders, but cannot determine a moral choice that relevant only to a few relatively common dis- involves social, religious, and personal values. In orders. the absence of compelling social justifications, decisions are and should be left to individuals, Effective use of genetic screening and selective families, and health professionals in a particular testing presumes public awareness that such tests situation. are available and acceptable. Families must wish to use the technologies and expect to benefit from Even if all diagnostic tests are available, there the information provided. This requires that there are families for whom the prospect of selective be no stigma attached to carrying a potential abortion is unacceptable, or who choose not to genetic defect and trust that genetic patient data avail themselves of genetic testing technologies will be properly used. (Issues relating to control for other ethical, religious, legal, social, or medi- of and proper access to genetic patient data are cal reasons. Such couples, while not at increased discussed below, and in app. B.) risk of having children with genetic diseases, will nevertheless inevitably bear some children with There are a few genetic diseases whose preva- genetic defects. The only way to avoid this would lence could be dramatically reduced. Huntington disease is a dominant trait encoded in chromosome 4 that causes a debilitating brain disease that ‘A method of detecting Huntington disease hefore s~wlptoms emerge, and men before hirth mav he ai,ailable within a decadt’- usually becomes evident only in a patient’s 40s a Whnique is alread~ a~ailahlr for ce]lain families (SW app A, it’ex - or 50s (after reproductive decisions have been Ier, 1984; Guse]la, 1%43: Rosenfeld, 198.$). 20 • Human Gene Therapy—Background Paper

be to circumscribe their liberty, making the judg- Complex traits such as intelligence and physi- ment that the potential social benefit overrides cal stamina, are not sufficiently understood to their autonomous right to choose what is best for merit serious contemplation of any genetic in- themselves and their families. The generally high tervention, and gene therapy could certainly not regard for personal autonomy in our society im- be justified, both because such intervention might plies that such couples’ right to make reproduc- not be considered ‘(therapy, ” and because there tive decisions will be protected.9 is no gene whose insertion would likely be effective. Even if gene insertion could reliably alter Existence of new mutations, absence or unavail- physical and mental abilities, many question ability of genetics tests, and freedom of choice whether it would ever be used, because it would all suggest that genetic diseases will continue to have to be cheaper and more effective than other exist, and therapies for them in infants, children, techniques for altering human characteristics. and adults will continue to be needed. Genetic techniques would have to prove more effective or less costly than education, indoctrina- Types of Genetic Disease That Are tion, physical and mental training, and drugs. Poor Candidates for Gene Therapy Now Dominant traits, and poorly understood re- CHROMOSOMAL DISORDERS cessive diseases are also poor candidates for gene therapy in the near future. Therapy of such In addition to genetic diseases that are caused disorders will depend on the specific cause and by mutation of single genes or small numbers of biochemical or metabolic manifestations of the genes, there are others caused by abnormal chro- disorder. To date, no dominant disorder is suffi- mosomes. One group of genetic disorders is ciently well understood to warrant an attempt at defined by a surfeit or deficit of chromosomes 10 gene therapy. There are, however, a few dom- in cells of the affected individual: patients have inant traits that could potentially be treated using an abnormal number of chromosomes or parts gene therapy. Gene therapy might eventually be of chromosomes. The most common such dis- contemplated for those enzyme defects inherited order is Down syndrome, which affects one in as dominant traits, and for diseases caused by 600 live-born infants. Chromosomal disorders deletions of small amounts of DNA that could be overall affect one in 200 newborns, and account replaced (there is some evidence for such dele- for half of all spontaneous abortions (Burrow and tions in retinoblastoma and Wilm’s tumor— Ferris, 1982). cancers usually developed in childhood that are Gene therapy for chromosomal disorders is not inherited as dominant traits). In such cases, the scientifically possible now, even in experimental decision to undertake somatic cell gene therapy animals. Chromosomal abnormalities involve the for the dominant disorder will not significantly improper placement, absence, or duplication of differ from consideration of recessive traits. fragments of chromosomes or entire chromo- Nevertheless, few dominant disorders have been somes. Chromosomes typically contain hundreds characterized biochemically, and simple gene in- or thousands of genes, and there are no tech- sertion may not correct many dominant dis- niques presently available for inserting enough orders. Correction of dominant diseases may re- DNA to correct such large defects in either somatic quire insertion of extensive amounts of DNA, gene or germ cells. surgery to remove the defective gene, or both; techniques for these more complex manipulations COMPLEX AND DOMINANT TRAITS have not been demonstrated in mammals. Pros- At present, there is a large technological gap pects for gene therapy of dominant disorders are between those diseases for which gene therapy therefore, in general, poorer than for recessive is promising in the near term and those about enzyme defects, although a few dominant diseases which so little is known that gene therapy can- might be addressed. not even be rationally contemplated,

‘L. Andrews, 1984d, citing Carey ~’. Population Sen’ices Interna- l~rhls genera ]lzatlOn does not app]}’ to traits that are dominant tional/, 431 U.S. 678, 685 (1977). in males and recessit’e in females (X-linked traits). Medical Aspects of Gene Therapy Ž 21

Reasons Germ Line Therapy known carriers of a recessive gene, only one in May Be Unnecessary 4 embryos would develop the disease, and so one unaffected and two asymptomatic carrier em- Germ line gene therapy may never be widely bryos would be treated for every one in which practiced because treatment of abnormal em- the disease was prevented. If parents have dom- bryos and gametes offers little advantage over inant or X-linked traits, at most half those treated selection of normal ones. would develop the disease. The situations de- Germ line therapy, as currently practiced in scribed are those that would yield the highest animals, involves taking embryos in vitro, genet- fractions of abnormal embryos; most other types ically altering them, and returning them to a of traits would have even less favorable ratios of female for further development. In early em- affected to normal embryos. bryonic stages, only a few cells are present. To Gene therapy on embryos is also made less determine whether the embryo is normal or ab- likely because of the need to ensure that it has normal would require that one have a test that been successful. Unless gene therapy were almost provided a diagnosis without disrupting the few certain to work, parents might seek to determine cells. No such tests exist at present.11 There are that the defect had been corrected, much as they prenatal diagnostic tests, but these are useful only can now ask for prenatal diagnosis. Checking the later in pregnancy, when many more cells can success of gene therapy would require either a be sampled to make a diagnosis without harm- test for the embryo before it were reimplanted, ing the fetus, 12 none of which exists, or availability of a test later in pregnancy and before delivery. If such a test In order to practice gene therapy on an early were available, it could be used for conventional embryo, one would have to treat either all em- prenatal diagnosis. Gene therapy of embryos bryos or only ones known to have a treatable genetic defect (Harsanyi, 1982; Pembrey, 1984). would thus not avoid the ethical dilemmas already Treatment of just those embryos carrying genes associated with conventional prenatal diagnosis, for a particular disorder would require a way to and would offer little advantage over selection of normal embryos or fetuses, while significantly in- identify them. If methods to identify embryos carrying the abnormal gene were available, though, creasing risks. For cases in which parents did not wish to check on the success of gene therapy, be- it would be easier and safer to merely select a normal embryo rather than treat an abnormal cause of religious convictions or because they one (Harsanyi, 1982). If all embryos are treated, would not change their actions based on prenatal then a significant fraction of normal embryos tests, this argument would not apply. would be unnecessarily subjected to the added There are certain situations in which germ line risks of gene therapy manipulations, The ratio of gene therapy might be contemplated. For exam- normal to abnormal embryos depends on the type ple, if a man and a woman both had PKU or sickle of genetic defect being treated. In the most com- cell disease and wished to have their own chil- mon scenario, involving two parents who are dren, then the parents and physician would know in advance that all embryos would acquire the 1 ITeChnlqUeS for separating animal embryos and gro~’ing identical twins from them have, however, been de~eloped (Nlaranto, disease because of the parents’ genetic constitu- 1984b). These same techniqes, if applicable to humans, might even- tion. This situation would eliminate the risk of un- tually be used to do diagnostic tests on celLs separated from the necessarily treating unaffected embryos, but embryo early in development. This would permit preimplantation and later prenatal genetic screening, and might also allow monitoring might still require a method for ensuring that the of the efficac~’ of gene therap~~ without harming the embryo or fetus. gene therapy had been successful (although par- This might, howe~er, be ethically unacceptable. ents might choose not to test this because of per- 12There are monomic and technical reasons, however, to inten- sify the search for techniques to detect genetic defects in single or sonal or religious beliefs). small groups of cells in early embryonic development. Techniques of in litro fertilization im’olve great economic cost and failures cause The strength of the arguments against germ line severe emotional distress; in this setting, a premium is placed on gene therapy would also diminish if gene trans- ensuring the normal status of embryos before the}’ are implanted. fer techniques became extremely reliable. How- 22 . Human Gene Therapy—Background Paper ever, this would require dramatic technical im- the animals observed to see if they express the provements in gene transfer and would not gene or develop side effects. eliminate the ethical dilemmas. Questions of safety include not only short term The medical complications of gene therapy sug- effects, but also long term consequences that may gest that germ line therapy on early embryos may require years to ascertain even in animals (if such never be ethically acceptable, even if it becomes long-term risks can be assessed at all). Intergen- technically feasible, except in extremely rare erational effects would be especially difficult to matings between parents whose genotype for a assess, but would be of concern only if germ line genetic disease is known. Uncertainty about pos- cells were affected. Long-term studies of multi- sible effects of such therapy in future generations ple generations of animals may also be required may preclude application of germ line gene ther- when and if germ line therapy is ever anticipated. apy for even these instances. Defects that could affect a patient’s progeny would be a concern if germ cells were affected Criteria for Beginning Human by gene therapy. Protocols for human gene ther- Gene Therapy apy of somatic cells will therefore be reviewed The decision to approve the application of gene for evidence that ensures that germ cells are not therapy to humans should depend on satisfaction affected (Working Group on Human Gene Ther- of several requirements. The requirements will apy, 1984). The risk of germ line effects has prece- be based on analysis of risks and benefits for the dent in cancer chemotherapy, radiation therapy, individual patient and consideration of the wider and some types of vaccination. Each of these tech- implications of approving gene therapy for any nologies has a risk of inducing new mutations in given patient. The factors considered in analyz- the patient that could be passed onto the patient’s ing which applications of human gene therapy progeny. If somatic cell gene therapy is done out- might be approved will include potential effec- side of the body, the risk of germ line effects is tiveness, safety, reliability, presence or absence likely to be extremely remote. If, however, exper- of alternative treatments, severity of symptoms, iments involve administration of gene therapy to and prognosis. Each of these will be considered the whole patient, then germ line side effects will in relation to a particular genetic disease in an be a concern, and such risks must be outweighed individual patient. Some generalizations about by the severity of the disease or the magnitude these factors, however, apply to the technique of of potential benefit in the individual patient. In gene therapy as a whole. the case of ADA or PNP deficiency, for example, the length of the patient’s life would be less than SAFETY 2 years and would be of low quality without gene therapy. For such a patient, the risk of germ line Judgments of the safety of gene therapy will effects might be acceptable, particularly if such be based on animal data and comparison to simi- effects could be detected and the patient’s repro- lar human interventions. For those few genetic ductive decisions informed by this knowledge. disorders, such as thalassemia, that have counter- parts in animals, short term safety can be assessed There are some special risks of using viruses by experiments that measure clinical improve- to transfer DNA, and assurances of the safety of ments in animals. For other diseases, it will be such transfer viruses will be prominent in ap- necessary to base judgments of safety on animal proval of human experiments (Working Group on data obtained in experiments that involve gene Human Gene Therapy, 1984). The special risks transfer, although clinical benefit in the animals of viruses include the possibility of rearrangement cannot be measured. Experiments might be per- of genetic material in the host that would lead formed, for example, using the same gene and to formation of an infectious agent. It is quite delivery system as would be used in humans, and probable that scientists will be able to design DNA Medical Aspects of Gene Therapy 23 derived from viruses that cannot revert to its better prognoses might then be treated by gene more infectious form (Rawls, 1984; Anderson, therapy. 1984).

One special concern relates to the potential EFFICACY mutagenicity and carcinogenicity of gene therapy Human gene therapy should not be approved using techniques now available (Rawls, 1984; until there is evidence that it might work; codes Anderson, 1984). It is not yet possible to control of research ethics require this. Commencement how and where inserted DNA integrates into that of experimental human gene therapy will require of the host cell. Insertion of genetic material may evidence from tissue culture and animal experi- thus lead to new genetic mutations in the cells ments. in the small number of diseases for which so treated (Gordon, 1981). It has also raised the there is an animal model, judgments of efficacy prospect that inopportune insertion of new DNA can be based directly on clinical correction of ani- may rarely cause or predispose a patient to de- mal diseases. In other diseases, constituting the velop cancer. Recent evidence about cancer genes majority of genetic disorders, it will be necessary suggests that certain cancers may be associated to base judgments on studies in tissue culture, with abnormal expression of genes that are present related human diseases, and relevant animal in normal cells. Abnormal expression has been studies. Experiments might produce evidence, for induced by viruses similar to those that are be- example, that the human gene were expressed ing developed to facilitate gene transfer, and in treated animals or could be expressed in the cancer-like characteristics have been induced by patients’ cells in vitro. The disorders in which techniques that closely parallel other methods gene therapy might soon be attempted do not that might be used for gene therapy (Hayward, have exact animal models, and so the earliest ex- 1981). The frequency with which gene transfer perimental human treatments may well be based results in deleterious mutation or predisposition on tissue culture studies and indirect animal ex- to cancer appears quite low, perhaps one in ten periments. thousand to one in a million, suggesting that risks may well be less than for cancer therapy, immune Demonstration of efficacy will require evidence suppression, or radiation (Working Group on that a gene can be delivered to a tissue where it Human Gene Therapy, 1984). Nevertheless, evi- can be effective, that it will remain in cells long dence for low risk of carcinogenesis will be ex- enough to have an effect, and that the product plicitly sought in the approval process preceding of the gene is sufficiently expressed. In some early clinical trials (Working Group on Human future cases, these factors may require that the Gene Therapy, 1984). transferred gene serve as a direct replacement for the abnormal host gene, occupying the same The short- and long-term risks of gene therapy location in the same tissue. In other cases, in- are not known. It is thus inappropriate to attempt cluding those for which gene therapy is being gene therapy except in the face of otherwise ex- seriously considered now, it may not be neces- tremely poor prognosis until more is known about sary to correct the defect so precisely. the risks. Determination of safety will likely derive from observations of animal experiments and In the case of ADA or PNP deficiency, for ex- the early instances of human gene therapy under- ample, it may require only a little enzyme pro- taken in patients with severe diseases—such as duced in bone marrow cells to sufficiently com- ADA deficiency, PNP deficiency, urea cycle de- pensate for the biochemical defect. The absence fects, or Lesch-Nyhan syndrome–that lack a of animal models indicates that the only way to preferable alternative therapy in a given patient; test this is to do a human experiment. This is seri- for such patients, even a low probability of ben- ously considered for ADA or PNP deficiencies efit may outweigh the uncertainties and risks of only because the diseases are rapidly fatal and treatment. If animal experiments and early human there is, for most patients, no alternative therapy. applications prove safe, diseases with somewhat Evidence for potential patient benefit for these 24 . Human Gene Therapy—Background Paper diseases may thus require only that the ADA or Many questions about efficacy will be addressed PNP enzyme be detected in bone marrow cells by future genetic and clinical research. Deter- of the patient following gene transfer. minations about which diseases can be treated and which methods are most successful must be Genetic diseases that affect the brain constitute made before human gene therapy becomes rou- a particularly large group of disorders for which tine medical practice. the question of organ specificity is crucial. There are several dozen genetic diseases whose most RELIABILITY prominent symptoms are neurological, including Tay-Sachs disease, metachromatic leukodystrophy Experimental or medical therapy should be Lesch-Nyhan disease, and phenylketonuria (PKU). undertaken only if the procedures are sufficiently The brain differs from other organs in two im- reliable to suggest that the potential scientific and portant respects. First, the nerve cells, whose im- clinical benefits outweigh the risks of ill effects paired function gives rise to symptoms, do not or failure. proliferate like bone marrow cells after they ma- Animal experiments involving gene transfer, ture. This implies that genetic material introduced with the exception of those done in lower orga- into one nerve cell cannot be amplified by allow- nisms, until recently had a relatively low prob- ing that cell to reproduce for many generations. ability of success in any one organism. This was Second, the brain has highly selective mechanisms tolerable to the investigators because their inter- for transporting substances from the bloodstream est was in gene expression and animal develop- to brain tissues. Correction of biochemical defects ment, and they could select the most scientifically elsewhere in the body may therefore not correct interesting result from a large population of ther- the defect in the brain, and may not eliminate apeutic failures. Such techniques are not accept- neurological or behavioral symptoms. able for correction of genetic diseases in humans, where there must be of potential benefit to the Doctors and scientists do not know which brain individual treated. defects can be corrected only in brain cells and which might be treated by modifying other Application of gene therapy in humans is now tissues. Lesch-Nyhan disease is due to the absence seriously considered only because of advances in of HPRT enzyme in all cells. Its worst symptoms the methods of delivering genes into cells and are due to disruption of brain functions. There stable expression of genes so delivered (Ander- is uncertainty about whether or not the disease son, 1984). can be treated by correcting the biochemical abnormality in cells other than brain cells (e.g., bone ALTERNATIVE TREATMENTS marrow cells) (Anderson, 1984; Merz, 1984). Fur- Gene therapy will be acceptable only if it offers ther, there is no way to test whether treatment the best prospect of success among all potential of bone marrow cells would cure the brain dys- treatments for a given patient. Factors that might function except through human experiments. If be considered in comparing gene therapy to alter- the disease could be treated by alteration of bone natives will include educated judgments about: marrow, then patients who already have this severely debilitating disease could be treated. expected efficacy, Otherwise, the only currently conceivable alter- anticipated costs (to the patient or overall), natives are treatment of cells early in development and (that might also entail germ line changes), or pre- magnitude and type of risks. vention of the disorder by prenatal diagnosis and Such judgments will vary from physician to 13 selective termination of pregnancy. physician and patient to patient, as for any medical technology. IWther alternatives, such as implantation of genetically altered nerve cells or insertion of genetic material using engineered viruses The genetic basis of a disorder does not imply specific for nerve cells, are theoretically possible, but have never that its treatment must also be genetic. There are been successfully demonstrated, even in animals. several treatments that have proven effective in Medical Aspects of Gene Therapy . 25 some genetic diseases. The clinical manifestations tient to receive the transplanted cells or organs. of hemochromatosis can be prevented by peri- A final disadvantage of transplantation is its ex- odic blood donation. Dietary treatments of PKU, traordinary cost. galactosemia, urea cycle defects, and several other There are thus several existing and prospective disorders considerably improve patient progno- treatment for genetic diseases that do not require sis, although they are only partially effective and direct gene replacement or supplementation, but impose substantial limitations on patients and all have limitations and many genetic diseases their families. Vitamin supplementation of those have no treatment. As one physician summarizes with Wernicke-Korsakoff encephalopathy and the status quo, “therapy of most genetic disorders several other disorders can be quite effective. is still ineffective and inadequate” (Friedmann, Drug treatments can compensate for some 1983). genetic defects. Clinical investigators have already Gene therapy of somatic cells will therefore discovered two drugs that lead to partial correc- probably prove technically superior to alterna- tion of sickle cell disease by inducing expression tive treatments for selected patients with some of a type of hemoglobin, normally only expressed disorders. during fetal development, that can compensate for the errant sickle cell protein (see Technical SEVERITY OF SYMPTOMS AND PROGNOSIS Note 4). Clotting factors can be given to hemo- The patient expected quality and length of life philiac patients, and biotechnology may greatly directly affect the potential benefit and accept- increase the availability and reduce the cost of able level of risk of any medical or experimental such factors. intervention. Extremely serious disorders, such Clinicians have also pursued the possibility of as Lesch-Nyhan disease and ADA and PNP deficiencies, have such poor prognoses that even directly administering enzymes that are missing small potential benefits are welcome and large due to genetic defects (Desnick, 1981). Such en- risks may be acceptable to the patient and his or zyme therapy has not been clinically successful, her family because they pale in comparison to but advances in drug administration could render such therapy practical. Development of drug continued life with the disease. pumps that reside in the body and deliver hor- Some examples of diseases likely to be targets mones, enzymes, or other chemicals for long peri- for gene therapy are noted by category in table 1. ods of time may reduce the need for gene ther- The number of patients likely to be treated are apy. A new insulin pump developed by NASA, for noted in table Z. example, promises to work for years without need for battery replacement (Langone, 1984). DATA MONITORING Gene therapy is not the only way to restore nor- For clinical trials to be optimally productive of mal genetic information to some organs of a pa- new knowledge, investigators must have mecha- tient with a genetic disease; some genetic defects nisms for following patients, and have a protocol may be remedied by transplantation of whole for obtaining whatever tissues may be needed and organs or tissues. Bone marrow transplantation for analyzing them. Advance thought about how has been successful, for example, in treating data monitoring will be done and disclosure of thalassemia, sickle cell disease, and immune defi- what it will involve to the human research Sub- ciencies; liver transplants have been performed jects should be an important aspect of any human for Wilson disease (Desnick, 1981; Friedrich, gene therapy experiments. Attention to data mon- 1984). Transplantation is a serious prospect for itoring will thus be one requirement for approval only a small minority of potential patients, how- to begin clinical trials. ever. This is because current methods require tissue compatibility between the donor and the INFORMED CONSENT recipient, a rare event, and because the methods Assurance that informed consent will be freely require highly risky treatments to prepare the pa- and appropriately obtained is required for all ex-

38-803 0 - 84 - 3 : QL 3 .

26 . Human Gene Therapy—Background Paper

Table 1 .—Examples of Diseases for Which Table 2.—Numbers of Patients Who Might Be Treated Gene Therapy Might Be Considered by Somatic Cell Gene Therapy in the Near Future

1. Protocols for human gene therapy in somatic cells Number of patients expected in next several years: Disorder with the disorder immunodeficiency caused by adenosine deaminase Adenosine deaminase 40 to 50 reported or purine nucleoside phosphorylase deficiencies deficiency worldwide (ADA or PNP deficiencies) Purine nucleoside 9 patients in 6 families Lesch-Nyhan syndrome (complete hypoxanthine- phosphorylase deficiency reported worldwide guanine phosphoribosyl transferase deficiency) Lesch-Nyan syndrome 1:10,000 males, estimated urea cycle defects caused by deficiencies of 200 new cases in the arginosuccinate synthetase (citrullinemia) or United States per year ornithine carbamoyl transferase (OCT, also known as Arginosuccinate synthetase 53 cases reported ornithine transcarbamylase) deficiency 2. Might be attempted in foreseeable future: Ornithine carbamoyl 110 cases reported phenylketonuria (as improvement on current dietary transferase deficiency treatment) SOURCE: Stanbury, et al., 1983, as modified by OTA. familial hypercholesterolemia defects of the urea cycle other than citrullinemia and OCT deficiency: arginemia (arginase deficiency) periments involving humans (Code of Federal Reg- mucopolysaccharidoses and other defined metabolic defects: ulations, 1983). In the case of human gene ther- Gaucher disease (some forms) apy experiments, this will include disclosure of metachromatic Ieukodystrophy (arylsulfatase B what can reasonably be expected about: deficiency type with little brain involvement) Hunter syndrome (enzyme detectable in normal blood) branched chain ketoaciduria (severe grades) 3. Farther off because protein expression may require regulation: treatment for them, hemoglobinopathies: (see Technical Note 5) costs sickle cell disease, hemoglobin SC disease • relative of alternative therapies, alpha and beta thalassemia hormone production defects therapies, 4. Farther off because gene product may be easily available for administration (diminishing the need for procedures that will be done to obtain clini- gene therapy): cal data on the gene therapy experiments, growth hormone deficiency; some other hormone procedures for dropping out of the study, production defects hemophilias and assurance that it is the patient’s right to 5. Unlikely unless new discoveries provide clues on how do so. to approach gene therapy: (Some may require germ line therapy because of All human experimental protocols should be re- access to tissue sites or immunologic problems with viewed by local Institutional Review Boards (IRBs), gene product.): Tay-Sachs disease and other metabolic defects that as is the case with all experiments involving primarily affect brain humans. In the case of human gene therapy, how- cystic fibrosis ever, the NIH recently revised the Guidelines for type 1A growth hormone deficiency most diseases inherited in dominant pattern (e. g., use of recombinant DNA to state that research Huntington disease, Marfan syndrome, proposals involving human gene therapy (pro- achondroplasia, etc.) posed by institutions that receive Federal funds 6. May not be applicable: chromosomal disorders: for recombinant DNA research) must be sub- Down syndrome mitted to NIH for approval, in addition to local environmental and multigenic disorders: IRB review. These protocols will be reviewed first hypertension by a Working Group on Human Gene Therapy, — diabetes “Cloned human gene available then by the Recombinant DNA Advisory Commit- SOURCE: Wissow, 1984. tee, and finally by the NIH Director before ap- Issues That May Arise From Clinical Application . 27

proval to proceed is granted. One purpose of this ject to potentially intrusive publicity. It is unlikely special care is to further insure proper informed that government oversight bodies can assure the consent of patients electing to participate in gene privacy of subjects who agree to participate in therapy experiments. FDA also has the author- gene therapy experiments, and so acknowledge- ity to oversee the adequacy of informed consent ment of this risk may be necessary by investi- in clinical experimentation involving new thera- gators before commencing. Investigators may also peutic products, and this might include gene in- need to anticipate responding to the demand for sertion technologies (Esber, 1984). media information by developing mechanisms for channeling interest through hospital spokesmen, One special aspect of human gene therapy, the preparing families to deal with the press, and potential for wide publicity, may merit attention careful observation of privacy safeguards. The in the process of securing informed consent. risk of media exposure is part of the process of Widespread interest in human gene therapy informed consent, because this may prove to be among scientific, religious, and government the salient difference between gene therapy and leaders in advance of its successful application other experimental medical techniques. suggests that the early clinical trials will be sub-

Issues that may arise from clinical application

If gene therapy moves through the early stages all hospitals, or only in certain ones? Who would of development and reaches the stage of stand- practice gene therapy, and where, may well be ard medical practice, several medical issues may determined by decisions made by the court sys- emerge. None of these is different in kind from tem, State and local Governments, national med- issues arising in connection with other medical ical specialty boards, and other medical and legal technologies, but the context of the new problems organizations. would be different. Parental responsibilities Medical malpractice Parental views on religion and medical practice, Issues related to malpractice may be raised by including those that might preclude even somatic gene therapy if it develops into a routine medi- cell gene therapy, might pit the beliefs of parents cal technology. Physicians could be sued, for ex- against standard medical practices. Many court ample, for failing to treat a genetic disorder. A decisions about whether to allow blood transfu- patient who suffered an untoward side effect be- sions to children of parents who reject such treat- cause of genetic changes induced by gene ther- ments on religious grounds exemplify this kind of apy might also bring suit. What would the stand- conflict. Some legal scholars have even contended ards of care for this technique be? that parents who fail to intervene on behalf of the health of their children might be forced to Several medicolegal issues might enter into do so. In one recent case, a woman who objected assessments of liability and responsibility, It is not to cesarian section on religious grounds was com- clear, for example, who would be qualified to pelled to undergo the operation to preserve the employ the sophisticated techniques of gene ther- life of the fetus (Lenon, 1983; Finamore, 1983). apy if it were to become standard medical prac- If gene therapy were widely available and stand- tice. Should all physicians do it? Only those cer- ard medical practice, analogous conflicts might tified by the American Board of Medical Genetics, arise. the National Board of Pediatrics, the Hematology and Oncology subspecialty board in internal medi- Whether medical practitioners, courts, institu- cine, or the American Board of Obstetrics and tional committees, or parents decide on who is Gynecology?. Should gene therapy take place at treated will depend on how gene therapy and 28 • Human Gene Therapy—Background Paper

other medical technologies are handled by the The review process by the National Institutes of courts or in new legislation at the State or Fed- Health (NIH) for approving experiments involv- eral level. ing proprietary information might require closed sessions, so that trade secrets were not disclosed patents and trade secrets publicly. The guidelines for human gene therapy The techniques involved in gene therapy involve formulated by the NIH (described below) are not the use of recombinant DNA to clone and insert binding on private firms that do not receive Fed- human genes. The early applications, if they in- eral research funds, although companies would volve the diseases listed in table Z, are unlikely be likely to seek NIH approval in any event to to involve patentable agents or processes, because avoid adverse publicity and to assure due proc- the methods under development have been openly ess for questions that arise about liability and in- published and developed at several centers, and surance. Finally, the flow of scientific and clini- the recombinant DNA involved is available in sev- cal information to other investigators might be eral laboratories. Eventually, however, the com- inhibited if trade secrets related to gene therapy plexity and variety of approaches to gene ther- must be protected. apy might result in products or processes that could be patented. Patents might be sought, for Insurance example, for genetically altered viruses designed Gene therapy might eventually be covered by to deliver the human gene to the target tissue or standard medical insurance, or it might require that permit controlled expression. The criteria for special provisions. Gene therapy, if it follows the granting such patents will be patentable subject model of other medical treatments, will not be matter, novelty, utility, and nonobviousness, the covered by insurance companies until its efficacy same ones used for other recombinant DNA prod- has been established for its intended application. ucts (OTA, 1984, ch. 16). The public policy issues Coverage by insurance will likely depend on the of fair access to the technology and encourage- particular disorder, the relative cost (for gene ment of innovation would also be analogous to therapy and the alternatives), and the safety and those for other medical technologies. efficacy of the techniques involved. A few distinctive aspects of patents and trade secrets are especially relevant to gene therapy.

Social implications of gene therapy

Gene therapy, should it prove useful, would be technical advance, and other factors can all in- like other technologies in changing the charac- fluence which applications are pursued and ter and kinds of decisions that individuals make. which eschewed. In an open and democratic It would provide new options for medical ther- society, new technologies are greeted by different apy and imply new responsibilities for making social groups in different ways. Some may believe such decisions fairly and for the benefit of both that beginning gene therapy too closely resem- individuals and society. In the view of many bles “playing God” or is too dangerous, while religious and ethical thinkers, gene therapy re- others impatiently await its application to the dis- stricted to somatic cell corrections of single gene ease affecting a loved one. traits differs little from other medical therapies (Neale, 1983; World Council of Churches, 1983; Siegel, 1982; Fletcher, 1982, 1983a, and 1983b). Background There are risks and benefits associated with be- The application of gene therapy to humans is ginning gene therapy, as with any new technol- likely to be regarded throughout society as a sig- ogy. Public policy, public education, scientific and nificant step, whether done in somatic or germ Social Implications of Gene Therapy 29 line cells. It will be a focus of attention because and mechanistic view of human life. To the ex- it is unprecedented and technologically sophisti- tent that this is true, however, it does not relate cated, and because it permits alteration of some- directly to gene therapy but rather to genetics thing considered fundamental to each individual— in general, and even more broadly to all of his or her genetic constitution. While genetic science. changes have been technologically induced for Social aspects of gene therapy that are men- years—for example, in the use of some vaccines-- tioned below fall into several general categories: the changes have never been so premeditated nor What process will determine when to begin so direct as deliberately inserting new human gene therapy? genes to cure a specific disease. As noted above, How important are evolutionary considera- however, the main difference between gene ther- tions? and apy and other medical technologies may be per- What might be the impacts on social insti- ceptual more than actual. The risks and benefits tutions? of gene therapy are analogous to those for other therapies, and many believe that it presents no fundamentally new ethical problems, yet there remains a gnawing discomfiture with the prospect. Major social issues

In the absence of gene therapy after birth, an WHAT PROCESS WILL DETERMINE WHEN TO individual has no role in the choice about which BEGIN GENE THERAPY? genes he or she carries, and so bears no respon- The process of deciding when to begin experi- sibility for carrying them. Once gene therapy is mental human gene therapy includes several com- available, this may not be the case, and individuals ponents. Some judgments are technical, involv- ma-y play some role in selecting their genes. This ing assessment of the expression of the gene of prospect is frightening to many because new interest, for example, and such decisions are left choices bring new responsibilities; new technol- to scientific peers to examine experimental design ogies can be misapplied. The magnitude of the or determine which studies are relevant to a pro- responsibility is, to a large extent, determined by posed project. Other judgments involve assess- the power of the new technology. If, as suggested ment of quality of life for a particular patient; above, gene therapy is not widely applied in the such decisions can only be made by the patient, near future because of limitations on the range his or her family, the physician, or others who of diseases to which it is applied, then the social are familiar with the details of a particular case. impact of gene therapy is likely to be less than Other judgments may involve determination of that associated with many other accepted medi- acceptable risk to society, and these invite wider cal practices. public participation. Most of the major social impacts of genetic Many of the questions raised will be answered knowledge will almost certainly derive less from only in the context of a particular patient in a par- gene therapy than from genetic screening or ticular family seen by an individual physician, and other genetic testing. Some fundamental choices the judgments of the parties most directly affected about privacy of data on patients’ genetic constitu- will decide the case within the constraints set by tion must be made as the new technologies pro- laws, regulations, and local ethics and human re- vide greater amounts of such information (see search committees. The context for making indi- app. B). The new information will, however, not vidual decisions will thus depend on peer review be directly related to developments in gene ther- and compliance with human subjects guidelines. apy) but rather to diagnostic evaluations of pa- The criteria for peer review and setting of guide- tients’ predispositions to genetic diseases or lines involve, in turn, government agencies that special health risks. must ensure fairness, completeness, and repre- Some fear that increased knowledge about how sentation of diverse and often conflicting view- genes work may further promote a cold, abstract, points. 30 . Human Gene Therapy—Background Paper

Judgments about whether a given experiment that someone can deny others the right to drive conforms to the criteria will differ among in- or ride in an automobile because there is an ever- dividuals. Some of the differences will reflect life present danger of an accident (Huntley, 1983, pp. experiences. A physician accustomed to treating 166-169). cancer patients will have different views from a Such conflicting views cannot be assuaged by scientist whose primary interest is developmen- empty assurances, and public policy decision will tal biology. A hospital attorney may hesitate to typically be made without consensus. There are endorse an experiment that the parent of an af- dangers in premature application balanced against fected child would eagerly embrace. One suspi- undue delays of useful medical benefits. Public cious of technology in general might reject exper- policy will be decided amidst great uncertainty. iments involving any level of risk. As one doctor noted, “the ethical principle that Some urge caution in approaching uses of gene physicians have to be concerned about is that we therapy. know what we’re doing before we promise that we’re going to try and treat someone” (Ryan, 1983, Once we decide to begin the process of human p. 172). In deciding when to begin experiments genetic engineering, there is really no logical place on human gene therapy, the need for further to stop. If diabetes, sickle cell anemia, and can- knowledge must be weighed against the benefits cer are to be cured by altering the genetic make- that might accrue to patients with severe and fatal up of an individual, why not proceed to other diseases. ‘disorders’: myopia, color blindness, left-handed- ness? Indeed, what is to preclude a society from Most of the social and ethical questions raised deciding that a certain skin color is a disorder? . . . about gene therapy could also be raised in the With human genetic engineering, we get some- context of other medical interventions, such as thing and we give up something. In return for se- use of antibiotics or acceptance of surgery. It is curing our own physical well-being, we are forced to accept the idea of reducing the human species not the questions that are new, but rather a new to a technologically designed product. Genetic technology that forces their reconsideration. engineering poses the most fundamental of ques- Disagreement about the seriousness of the new tions. Is guaranteeing our health worth trading social and ethical consequences of using gene away our humanity? (Rifkin, 1983, pp. 232-233). therapy in humans hinges on incompatible judg- In contrast, an urgent request for support of ments of how widely it will be used and how revolutionary will be its perceived impact on how gene therapy research is found in the words of humans view their own sanctity. Most scientists Ola Huntley, three of whose children suffer from and clinicians believe that gene therapy will be sickle cell disease: only a small incremental medical advance appli- I resent the fact that a few well-meaning in- cable to a few patients, while religious and social dividuals have presented arguments strong enough commentators may reflect on its cumulative ef- to curtail the scientific technology which promises fects over generations. The general interest in to give some hope to those suffering from a human gene therapy has led some scientists and genetic disease. I have faith to believe that genetic medical providers to urge caution so as to avoid therapy research, if allowed to continue, will be political reaction against gene therapy among the used to give life to those who are just existing . . . .I, too, would like to ask the question, who do general population (Rosenberg, 1983; Grobstein, we designate to play God? Aren’t those theolo- 1984). gians and politician; playing God? Aren’t they Public policy will have to be based on consid- deciding what’s best for me without any knowl- eration of patient welfare, social impacts, religious edge of my suffering? I am very angry that anyone would presume to deny my children and precepts, and political realities. There is little rea- my family the essential genetic treatment of a son to believe that differences in opinion about genetic disease . . ..1 see such persons as sim- the appropriateness of human gene therapy will plistic moralists who probably have seen too resolve spontaneously, or even after extensive many mad scientist horror films. It’s like saying public discussion. Where there is no agreement Social Implications of Gene Therapy . 31

on what decision to make, the only alternative is Discussion of germ line gene therapy is most a process for making the decision, and govern- relevant to permanently changing the human ment agencies must demonstrate that the proc- gene pool because it would lead to inherited ess is rational and fair (Bazelon, 1983). changes. At present, however, such discussion is necessarily vague and speculative because the Wide public discussion and agreement on a technology does not exist and may never be used. process do not guarantee fair decisions or cor- There will doubtless be continued public inter- rect assessments of risk and benefit. Errors of est in ensuring fair and open debate on whether judgment may occur even with unassailable ex- human germ line gene therapy would be appro- pertise and completely democratic participation. priate. It is impossible, however, to make esti- Resort to fair and open process is not, therefore, mates of the potential magnitude of its impact on perfect, but merely the best practical solution to human populations now. assure fairness. The effects of somatic cell gene therapy will de- Given the anticipated public interest in and con- pend on how many patients receive such ther- troversy about human gene therapy, any suc- apy, and to which conditions it is applied. It is not cessful mechanism for permitting its commence- possible to make firm predictions about how ment will involve a public process including many patients might eventually be treated by discussion among individuals with different in- gene therapy, because it is not now certain that formed perspectives. Such discussion may arrive even somatic cell gene therapy will prove medi- at consensus, but if it does not, documentation cally useful. The effect that somatic cell therapy of the fairness and rationality of the decisionmak- would have on human population genetics would ing process will be the only practical course. The be no different in kind than that from other tech- Federal Government will be involved in decisions nologies that affect the patient and do not lead about human gene therapy because of its involve- to inherited changes, Most of the changes would ment in medical research, health care, and issues be due to preservation of the lives of those who that attract wide public interest. would otherwise die before reproducing, the There are several Federal agencies already in same effect that results from diet therapy in PKU, place that can educate the public and make deci- or clotting factor replacement in hemophilia. sions about when to begin human gene therapy. While it is not possible to estimate the number These include the Recombinant DNA Advisory of patients that might eventually be aided by Committee of the NIH, the Food and Drug Admin- somatic cell gene therapy, it is possible to estimate istration, and several other bodies within the de- the impact of correcting those genetic defects that partment of Health and Human Services. These are currently targeted. These will be the poten- will be described below in the section on the Fed- tial genetic impacts that must be assessed by those eral Role in Gene Therapy. approving the early experiments in gene therapy. HOW IMPORTANT ARE EVOLUTIONARY As can be seen in table 2, the diseases for which CONSIDERATIONS? gene therapy is now contemplated are quite rare. The total number of patients with these condi- Direct manipulation of the genome inspires vi- tions that might be treated using somatic cell gene sions of mankind controlling its own evolution, therapy would likely be less than 300 per year depleting the diversity of genes in the human in the United States, and would probably be far population, and crossing species barriers to create fewer until the technology were accepted. This new life forms. The magnitude and rapidity of figure compares to the approximately 4 million change caused by direct genetic intervention, however, are likely to be far smaller than the large births in the United States each year. effects caused by relaxing historic selection pres- Changing the Gene Mix in Human Popula- sures on the human population through changes tions.—Somatic cell gene therapy would have no in the environment, sanitation, and health care. direct effect on the mix of genes in human popula- 32 Human Gene Therapy—Background Paper tions, and would have only the indirect effects Genes causing other genetic diseases may also noted above. Germ line therapy, in contrast, serve a purpose that has not been discovered, and would alter the prevalence of some genes, also elimination of such genes might prove deleteri- though the magnitude of such effects is impossi- ous to the human population in the long run. In ble to predict because so many factors are in- somatic cell gene therapy, the patient own genes volved. would not be deleted, but new information would Direct germ line gene therapy of recessive be added in such a way that it would not be in- disorders would, for most diseases, have a notice- herited. This would have no impact whatever on able effect on human evolution only if widely the population’s reproductive gene pool. If gene practiced for hundreds of generations. The num- therapy permitted the survival of patients who ber of generations needed to have a significant would otherwise die, however, then genes caus- effect would depend on the type of gene being ing diseases might slowly become more wide- corrected, its prevalence in the population, when spread because they would not be eliminated. the disease were expressed (in adulthood or Even if gene therapy did have an effect on childhood), the severity of the disease caused by genetic diversity, this might not prevent its use, it, and many other factors. If gene therapy were The risk of slightly reducing diversity in the en- used only to treat single gene recessive traits, then tire human population would likely seem insignifi- it would take several hundred generations mea- cant to those patients for whom the potential surably to alter the prevalence of the gene in the benefits loom large and immediate. Perpetuation population. For defects that are present on one of genetic disease, particularly of the severe percent of chromosomes in the human popula- childhood diseases that are now the targets for tion, for example--corresponding to a genetic dis- gene therapy, would seem a cruel means to an ease much more common than any under consid- end of uncertain import. eration for gene therapy now—it would take 1,500 years to increase the frequency to 2 per- The sickle cell example is instructive in this cent.14 If germ line gene therapy were widely sense, as well. While it is widely accepted that the practiced for a large number of diseases, in- sickle cell gene conferred certain advantages in cluding common dominant traits, then alterations combatting malaria among Mediterranean popula- might be noticed much more quickly, but such tions, it is also true that current antibiotics and applications are not now envisioned. sanitation technologies have been much more effective in protecting the same populations. In the Depletion of Diversity in the Gene Pool.-– era of modern medicine, sickle cell disease is no There is excellent evidence that some genetic dis- longer a necessary price to pay for genetic pro- eases are common because of an advantage con- tection from the ravages of malaria. ferred to those individuals who carry one copy of the aberrant gene. Those who carry one copy The arguments for refraining from gene ther- of the sickle cell anemia gene, for example, are apy in order to maintain genetic diversity are also better able to combat malarial infections. The weakened when raised in a population whose genetic disease is the price paid to preserve this main long term problem may be the very rapidity advantage for the population on average, miti- of its growth. When a population is rapidly ex- gated only by the statistical rarity of having two panding, the diversity of genes generally increases abnormal genes (and thus the disease) (Vogel, because there are more individuals who can carry 1979). new genes. ltrrhis examp]e is based on discussion of eliminating rare genes Crossing Species Barriers. -Recombinant gen- for recessi~e disorders in several references (Li, 1961; Vogd, 1979). etic technologies permit genes from one species These assume that those who carry two copies of a defective gene would not reproduce. In considering the impact of human gene ther- to be inserted into another. In the animal experi- apy for those who would otherwise die before reproducing, the ments cited, for example, rat growth hormone situation is reversed but the time scales would be comparable, genes were put into mice and rabbit globin genes Social Implications of Gene Therapy 33 into rats. It is unlikely that an animal gene would Concern about Rubella infection, particularly be used for human gene therapy, because if an its proclivity for causing congenital malforma- animal gene is available, then isolation and clon- tions, intensified following the epidemic of 1964, ing of its human counterpart would be routine. It was well known that Rubella infection during Human genes will be used in animals, however, pregnancy could cause malformations, but the to test the safety and efficacy of gene therapy mechanisms were not clear. Investigation of the before it is tried in humans. What would be the epidemic was advanced by research on fetuses significance of using human genes in animals? that either spontaneously aborted or were aborted because an infected woman chose to Mythology and literature contain numerous ex- avoid the risk of bearing a deformed child. Fetal amples of hybrid creatures that combine the char- research showed that a majority of fetuses in acteristics of man and beast or involve engineer- women known to be affected had been directly ing completely new organisms (Capron, 1984c; infected by the Rubella virus, that the deforma- Siegel, 1982). One need only think of the minotaur tions were likely due to direct fetal infection, and (the apocryphal man-bull hybrid of Crete who that fetal infection often persisted long after the devoured fair youths from ancient Greece), the woman was no longer symptomatic (Horstmann, golem (a creature of Jewish lore created to pro- 1965). tect the residents of Prague; the golem eventually turned against them and had to be destroyed), Fetal investigation also led to the development or Frankenstein’s monster to note the horror asso- of Rubella vaccines. Many vaccines were devel- ciated with semi-human creatures, It is widely ac- oped during the mid-1960s, including the RA 27/3 cepted in the religious and professional ethics vaccine derived from an infected human fetus communities that attempting to create such crea- and propagated in tissue culture of human cells tures would be immoral (World Council of (Plotkin, 1965; Plotkin, 1969). This strain is now Churches, 1982; National Council of Churches, the only Rubella vaccine licensed for use in the 1984; Siegel, 1982,1983); it is also impossible to United States (Plotkin, 1981). create such creatures by attempting to alter single gene defects. Some of the issues raised by inter- Finally, the guidelines for use of Rubella vac- species transfer of genes are further discussed cines were influenced by human fetal research. in Technical Note 3, Animal experiments showed that Rubella could infect fetuses of pregnant females (Parkman, FETAL RESEARCH 1965), as was expected from human studies. Pre- Research involving human fetuses is a topic of liminary experiments in monkeys, however, did controversy in the United States, and 25 States not show fetal infection by the weakened Rubella have statutes that limit or prohibit it (Andrews, used in vaccination (Parkman, 1966). The num- 1984b; Quigley, 1984). Fetal research bears on ber of monkeys tested was necessarily small be- gene therapy primarily if germ line gene therapy cause of the expense and difficulty of animal exis considered. If germ line gene therapy on human periments, and investigation of humans proved embryos is to be undertaken, it must rest on a necessary. Scandinavian workers showed that in foundation of knowledge about development and contrast to the monkey experiments, vaccine genetic expression in very early human embryos. strains might infect the human fetus (Vaheri, Such knowledge can only be obtained using such 1969). These experiments could only be done on embryos. aborted fetuses. The findings were considered in drafting the recommendations for use of vaccines Even if germ line therapy is not considered, in pregnant women (Recommendations, 1969). there may be instances in which fetal research would be useful in establishing safety or efficacy The strains of vaccine now in use are different of somatic cell gene therapy. The history of re- from those used in the Scandinavian experiments, search on Rubella during the 1960s may illumi- and further research on current strains (involv- nate the utility of fetal investigation in several ing women who have inadvertently been vacci- respects. nated during pregnancy) has demonstrated that

34 • Human Gene Therapy—Background Paper the risk of fetal infection from Rubella vaccina- tity of human life. The effects of the new tech- tion during pregnancy is quite low (Plotkin, 1981). nology on attitudes are not certain, however, and the same commentators note that appreciation of Fetal research thus played a role in better un- the complexity of life may increase our regard derstanding the congenital Rubella syndrome, in for life more than it attenuates it. The attempt development of vaccines, and in establishing safe to save lives by gene therapy is itself an attempt practices for human vaccination. An analogous to preserve or improve particular lives. The spe- role in establishing scientific background and cific effect of gene therapy in changing percep- testing safety and efficacy of gene therapy might tions is, in any case, likely to be one small part also require fetal research for some future ap- in the general growth of science, complementing plications. other fields that also alter our self-perceptions There is no reason to test human gene therapy such as neuroscience, computer science, psychol- protocols in human fetuses now because neither ogy, evolutionary biology, ecology, and other fetuses nor pregnant women are contemplated parts of biology and medicine. If gene therapy is for treatment. Should this change, then tests in- found medically useful, it may prove difficult to volving fetuses would be desirable. If a need for deny benefits to needy patients on the basis of application to fetuses or pregnant female patients long-term shifts of human self-perceptions. emerges, then it may depend on study abroad Gene therapy may play a larger role in in- (where fetal research is practiced), relaxation of directly altering parental expectations. If genetic fetal research guidelines in the United States, or therapy is successful for extremely serious dis- repeal of statutes in those States that prohibit such eases, then it might be applied over time to pro- research (if the research is to be conducted in gressively milder medical problems. This prospect such States). This issue will be especially difficult raises the possibility that parents may more and to resolve if gene therapy is shown useful for more expect “perfect” children. So long as gene severe diseases of early childhood. This is because therapy is confined to disorders that are recog- gene therapy that is useful in infants is likely, in nized as significant burdens, then it will merely some cases, to be potentially even more beneficial bean addition to the medical armamentarium. If during fetal development–before the metabolic it becomes possible to treat more and more dis- abnormalities caused by the genetic disease have orders, especially if attempts are made to affect caused any deformities or irreversible effects on intelligence or physical traits, then gene therapy the nervous system. might indeed raise concern about parental expec- WHAT MIGHT BE THE EFFECTS ON tations of their children. Again, however, the def- SOCIAL INSTITUTIONS? inition of appropriate application is one that must be widely discussed because it is more a social Several religious leaders have noted that gene than a medical issue (although medical factors are therapy may be one more factor tending to re- highly relevant). Discussion of such potential duce perceptions of humanity to mechanistic in- dangers is, given present technology, mere spec- terpretations (Zaner, 1982; Siegel, 1982, 1983; ulation for now; as the technology develops, pub- World Council of Churches, 1982; National Coun- lic discussion may need to be encouraged if it cil of Churches, 1984). Focus on mechanism may appears that gene therapy is becoming widely lead to diminished attention to social and moral applicable. values, and may threaten attitudes about the sanc-

The Federal role in gene therapy

The Federal Government performs several cal research is supported by the Federal Govern- functions that may affect the development and ment through the National Institutes of Health application of human gene therapy. Most biomedi- (NIH) and other Executive agencies. Regulation of The Federal Role in Gene Therapy 35 pharmaceutical products is the responsibility of restriction to centers of demonstrated exper- the Food and Drug Administration (FDA). Genetic tise, and, interestingly, services including manpower training, basic and exclusion of genes that are "the object of applied research, genetic screening, and counsel- commerce .“ ing, are partially supported through block grants A recent report on reproductive technologies given to individual states under authority of the was submitted to the Parliament of the United National Sickle Cell Anemia, Cooley’s Anemia, Tay- Kingdom by a committee headed by Dame Mary Sachs and Genetic Diseases Act (Reilly, 1977), and Warnock. The report recommended that a new administered under the Omnibus Budget and governmental licensing agency be created to over- Reconciliation Act. Finally, the Federal Govern- see embryonic and fetal research and its applica- ment, through its legislative, judicial, and Ex- tions. The committee also briefly commented on ecutive branches, is often an effective instrument potential germ line gene therapy, and recom- for public discussion and education, through the mended that the licensing authority give “guid- Department of Health and Human Services, con- ance on what types of research, apart from those gressional hearings and activities, and such agen- precluded by law, would be unlikely to be con- cies as the President’s Commission. sidered ethically acceptable in any circumstances” (Committee of Inquiry, 1984). The licensing au- International interests in human thority would thus monitor gene therapy re- gene therapy search and consider whether germ line therapy should be permitted. Human gene therapy is widely regarded to be closer to clinical testing in the United States than European political history in dealing with any other country. Other developed nations will genetic technologies differs from that in the soon follow, however, and international interest United States. The United Kingdom, for example, in its development has been noted, primarily in has approached the regulation of novel biological Canada and Europe. Canadian research groups technologies from a different perspective (Wol- have been involved in the design of viruses that stenholme, 1984). Fetal research is now per- might be used in gene transfer (Merz, 1984), and formed in the United Kingdom and Australia, and several European government groups have made so questions regarding its regulation are more statements related to gene therapy. The Parlia- prominent there than specific applications to gene mentary Assembly of the Council of Europe, for therapy. In the United States, fetal and embryonic example, made a recommendation that ‘(the rights research has not been federally funded for almost to life and human dignity . . . imply the right to a decade (see below), and the scientific and med- inherit a genetic pattern which has not been ar- ical focus of gene therapy has been on somatic tificially changed,” although this right was ex- cell therapies whose development does not en- plicitly qualified so as to “not impede development tail the use of fetuses or embryos. of the therapeutic applications of genetic engineering (gene therapy), which holds great promise . . . “ (Parliamentary Assembly, 1983). The Federal agencies potentially involved Parliamentary Assembly also called for the devel- in gene therapy opment of a list of diseases that could be treated Several Federal agencies potentially have pur- using gene therapy, based on several criteria: view over some aspect of human gene therapy. seriousness of the disease, The National Institutes of Health, as the primary simplicity of the technique and applicability sponsor of relevant research and the location of to only single gene disorders, the Recombinant DNA Advisory Commission, is application to a well characterized disease, involved in approving both research grants to do supervision by. scientific and ethical review gene therapy research and in overseeing com- commit tees, pliance with Federal research guidelines. 36 . Human Gene Therapy—Background Paper

The National Institutes of Health (NIH), through tional trials support the safety and efficacy of the its Recombinant DNA Advisory Committee (RAC), product for its intended labeled claims (Miller, is currently the most active Federal body involved 1983b). in monitoring human gene therapy. It was established in 1974 and is charged with recommend- In addition to the NIH and FDA, which are ing guidelines for safe conduct of research involv- already monitoring human gene therapy, there ing recombinant DNA (or, by extension, RNA) are several other Federal agencies or bodies that (Milewski, 1984). The RAC has established a might become involved in the future. Working Group on Human Gene Therapy, whose An Ethics Advisory Board (EAB) is an entity members are listed in appendix C, to develop composed of non- government experts in ethics, guidelines for research on human applications of law, medicine, and others with expertise related gene therapy. The Working Group plans to have to a particular topic under consideration. One guidelines published in 1985, in anticipation of such board was formed in 1979 to advise the Sec- proposals for human gene therapy, The Work- retary of Health and Human Services on several ing Group shall evaluate research proposals re- topics, most notably fetal research. Federal reg- ceived by NIH, and shall report to RAC. RAC shall, ulations state that “One or more Ethical Advisory in turn, report the the Director of the NIH, who Boards shall be established by the Secretary” will then approve the proposal or suggest needed (Code of Federal Regulations, 1983) yet no such alterations. Another function of the Working board exists at present. An EAB was intended to Group will be to educate the public and to review “render advice consistent with the policies and some broader social implications of human gene requirements . . . as to ethical issues)” (Code of therapy that are not included in review by local Federal Regulations, 1983). Such a board, if it Institutional Review Boards (Working Group on were now reconstituted, might play a role in co- Human Gene Therapy, 1984). ordinating and overseeing the Federal Govern- The Food and Drug Administration (FDA) will ment’s activities regarding human gene therapy, also play a role in regulating some aspects of including public education, supervision of NIH, human gene therapy. The FDA has the author- FDA, and other agencies in the Department, and ity to regulate drugs, including biological prod- advising the Secretary on other actions. Consid- ucts intended for use in the diagnosis, treatment, eration of the broader questions related to pro- or prevention of diseases or injuries in humans. gress in human gene therapy would fall within The FDA will become involved in human gene the mandate established for EABs. therapy if it involves products such as nucleic The Federal Interagency Advisory Committee acids or genetically modified viruses that are sub- on Recombinant DNA Research, established in ject to agency regulations (under authority of the 1976, is another group that has not played a di- Food Drug and Cosmetic Act and the Public rect role in human gene therapy, but could theo- Health Service Act) (Miller, 1983a). The role of the retically do so. The Committee is composed of FDA generally includes review of applications sub- members from several Federal agencies involved mitted for products used in investigational studies in activities related to recombinant DNA research. and encompasses the manufacture and quality Members of the Committee agreed to comply with control procedures applied to such products. The the NIH Guidelines in 1976, thus in effect trans- FDA review includes evaluation of the design of ferring authority to NIH for biomedical research clinical and preclinical studies, adequacy of pro- and clinical investigations. Recently, other agen- cedures for assessing safety and efficacy, and cies, including the Department of Agriculture and methods for obtaining informed consent from pa- the Environmental Protection Agency (both of tient participants (Miller, 1983b). which have members on the Interagency Com- The FDA authorizes (by approval of a New Drug mittee), have become involved in regulating agri- Application or granting of a license) the market- cultural and environmental applications of recom- ing of products when a review process has con- binant DNA research. The Committee may thus cluded that the data obtained during investiga- play a more active role in agricultural, environ- The Federal Role in Gene Therapy . 37 mental, and other new areas of research, but it gene therapy) (Conference Report, 1984). The leg- is likely that most authority to monitor and reg- islation reported from conference was passed by ulate human gene therapy will remain at NIH and both houses, but vetoed by president Reagan on FDA because these agencies have the most exten- October 30, 1984. The future of a Federal body sive experience with biomedical and clinical ap- for investigation of bioethical questions is thus plications. uncertain. The Office of Science and Technology Policy Functions of the Federal Government (OSTP) is an Executive agency, headed by the President Science Advisor, that reports directly to the President. The OSTP has taken a lead in SUPPORT OF RESEARCH Federal oversight of some areas of science and The Federal Government, through the National technology, and has recently coordinated a group Institutes of Health (NIH), is the primary sponsor of government officials in dealing with the ques- of biomedical research in the United States. The tions surrounding deliberate release of genetically NIH budget for 1983 was $3.8 billion, account- altered organisms into the environment, and ing for 36 percent of all funds spent in the United other novel applications of biotechnology. The States on health-related research (NIH, 1984). In OSTP could conceivably also serve a similar func- those areas of biological science related to human tion for gene therapy, although the extensive ex- gene therapy, the NIH funds the bulk of research, perience of FDA and NIH in questions relating to although a few companies with expertise in bio- health and medical technologies makes OSTP less technology are known to be sponsoring some re- likely to be involved in human gene therapy than search relevant to gene therapy. in more general questions such as environmental The relative rarity, scientific difficulty, and long release or new agricultural applications. term investment necessary to develop gene ther- Determination of the Federal role in monitor- apy for any one genetic disease suggest that re- ing and public debate about questions relating to search may not occur unless there is public fund- bioethics, including human uses of recombinant ing. Individual genetic diseases are thus “orphan” DNA technology, was a focus of considerable disorders when taken singly, yet relatively com- legislative activity in the 98th Congress. Bills to mon as a group. The technology to identify or reauthorize the lapsed President’s Commission treat one genetic disease often suggests means for were introduced in both houses, but no further approaching biochemically similar disorders, and action on those bills was taken. Representative many aspects of research on on one disorder may Gore proposed a new President’s Commission on be directly applied to others. A recent example Human Applications of Genetic Engineering that of this phenomenon is the discovery that the gene eventually became part of the House version of for Huntington disease is located on human chro- the NIH authorization bill. Senators Hatch and mosome 4. This discovery was made by applying Kennedy proposed creation of a bioethics com- a technique developed for general mapping of the mission at OTA as part of legislation creating a human chromosomes to large families in the new National Institute of Arthritis and Musculo- United States and Venezuela’s (Gusella, 1983; skeletal and Skin Diseases at NIH. The Senate and Wexler, 1984; Rosenfeld, 1984; Kolata, 1984a). House bills were referred to conference. The con- The same technique, which may permit earlier ference report authorized a new Biomedical diagnosis and eventual identification of the spe- Ethics Board, composed of 6 Senators and 6 Rep- cific gene responsible for the disease, promises resentatives, and a Biomedical Ethics Advisory to apply to many other genetic diseases. The fi- Committee, composed of 14 appointed individuals nancial and scientific investments in discovering and experts in relevant disciplines. The Commit- tee would have performed studies related to lq-he te~hniqu~, called restriction fragment length polymorphism bioethics, including two mandated studies: one linkage anal~sis, was de~’eloped to locate genes ei’en when the gene had not been c]oneci or e~en identified IBotstein, 1980, 1984). This on fetal research and another on human applica- method for identifJ’ing the chromosornal location of genes is de- tions of genetic engineering (including human srrihed in app, A. 38 . Human Gene Therapy—Background Paper and developing a technique used in locating the formation on compliance with standards for ani- Huntington disease gene may thus also pay off mal care). The proposal is sent to local review for other disorders. committees that assess its compliance with safety and human subjects protection guidelines. Cer- Research on genetic diseases is likely to contain classes of experiments are automatically re- tinue to depend heavily on Federal funding, and ferred to NIH for approval, and cases that can- so long as gene therapy remains experimental, not be decided locally are also referred to NIH. Federal research policy will be influential in its development. Seminal discoveries related to These procedures are the ones followed by human gene therapy will likely derive from both scientists and clinicians using Federal funds who clinical research and basic research on molecular act in good faith. Human investigations supported genetics and biochemistry. The technologies of by private firms must also meet human subjects recombinant DNA and gene transfer now con- protections guidelines, usually to avoid problems templated for use in human gene therapy are of liability and insurability. Clinical investigations themselves results of basic genetic inquiry, and of pharmaceutical products, including genes or further practical applications of basic research modified viruses used in treatment, must also be are likely to emerge. This has been the pattern submitted for FDA review. of development of molecular biology and other Ensuring Compliance with Human Subjects biomedical sciences-research in one area leading Protections.—A process for protecting human to breakthroughs in an unexpected and seemingly subjects in research already exists. In the context unrelated discipline. The discovery of DNA’s rela- of experiments involving human gene therapy, tionship to inheritance was itself such a seren- a proposal for an experiment involving human dipitous discovery, resulting from Avery’s work subjects should be sent to an institutional review attempting to identify why certain bacteria caused board (IRB), a local committee that would then pneumonia (Thomas, 1984; Judson, 1980). review the proposal for compliance with human Research on developing animal models of hu- subjects protection standards, according to the man genetic diseases may be important in facil- following criteria: itating human gene therapy applications. Such minimization of risk to the subjects, models provide methods for testing the efficacy reasonable risks in relation to anticipated and safety of treatment methods. benefits, In addition to basic research, some early exper- equitable selection of subjects, imental trials in humans will likely be supported assurance of informed consent, by Federal funds. Decisions about how Federal adequate provisions for monitoring data, research funds are expended for research on provisions for protecting patient privacy, and basic molecular genetics, animal models of genetic assurance that decisions to participate in re- diseases, and preliminary human applications will search will not be coerced (Code of Federal thus directly affect how rapidly gene therapy Regulations, 1983). develops and which diseases will be addressed. Approval by a local IRB will be required before proposals are forwarded to NIH for approval. IRB REGULATION OF MEDICAL APPLICATIONS approval may be contingent on approval by the A research proposal involving recombinant NIH. When received at NIH, the proposal will be DNA is generally originated by a scientist work- published in the Federal Register for public coming at a university, industrial laboratory, or other ment and will also be referred to the Working research center, A research proposal includes Group on Human Gene Therapy, which will then general background, goals of the experiment, report to the RAC for review. If the proposed ex- methods to be used, evidence for efficacy, provi- periments meet the standards of the RAC, then sions for assuring safety and informed consent they are referred to the NIH director for approval of patient participants (and may also include in- (Working Group on Human Gene Therapy, 1984). The Federal Role in Gene Therapy . 39

Ensuring Safety and Efficacy.—Mechanisms for human gene therapy, could be performed by an reviewing research proposals to ensure safety po- EAB, congressional commission or other Federal tentially fall under the authority of several groups. body. Assurance of safety is analogous to human subjects protection, including review by NIH and FDA In addition to review of research proposals on after approval by local safety and human subject human gene therapy by the NIH, the Food and committees. Each investigator must submit his re- Drug Administration (FDA) also has authority over search proposal to his or her local Institutional human experiments involving therapeutic products. Biosafety Committee (IBC), which assesses com- Genes introduced for gene therapy could con- pliance of the proposed experiments with NIH stitute such a biological product under FDA juris- safety guidelines for recombinant DNA research. diction and would thus involve FDA approval In the case of human gene therapy, the risks and before commencing (Miller, 1983b). FDA oversight benefits of proposed experiments will also be re- would follow regulator. procedures used for viewed, followed by approval by the NIH and FDA other products: submission of evidence for safety before commencement (Krause, 1984, p. 17847). and a rational basis for introduction of the product into humans (stemming from animal experi- There are several weaknesses in this regulatory ments, in vitro studies, and relevant previous clin- schema. Only research conducted at institutions ical trials), Investigator submissions must include accepting federal funds for recombinant DNA ex- data showing that the product is adequately pure periments are obligated to conform to the NIH and sufficiently potent to justify clinical trials (Of- Guidelines by law, although to date private re- fice of Biologics Research and Review, 1983). The search groups have voluntarily submitted to RAC FDA then evaluates the evidence and determines Guidelines. (Private corporations have complied whether risk and benefit considerations support at least in part because of the risk of public cen- clinical trials. sure, potential loss of insurance coverage, and possible added legal liability in civil suits if they FDA authority may, in some circumstances, do not.) The formal penalty for not conforming overlap that of the NIH, whose Guidelines ex- to NIH guidelines is denial of Federal research plicitly provide for oversight of human gene ther- funds to the institution submitting the proposal. apy and experiments that involve recombinant This is quite powerful for universities and most DNA (or molecules derived from rDNA). research centers, but is not a direct economic incentive for compliance in some privately spon- Whatever the mechanism or agency involved, sored research. protocols and products will be evaluated case by case. This will certainly involve local IRBs, NIH, Another feature of the current review process and FDA, and may eventually include other Fed- is the lack of evaluation of research goals. IRBs eral agencies as well. If individual applications of are specifically precluded from assessing the human gene therapy becomes standard medical ‘(long-range effects of applying knowledge gained practice, or even widely available, they will then in the research” (Code of Federal Regulations, be governed primarily by professional standards, 1983). This is quite appropriate in the context of civil suits, or local authorities, like other medical a particular experiment involving patients with technologies. specific defects, and IRBs cannot be expected to do more than investigate specific protocols. The For early experiments on human somatic cell lack of purview over goals, however, leaves a gene therapy, present oversight methods that in- vacuum for determining which experiments are volve local IRBs, RAC, NIH, and FDA appear ade- contrary to public policy. The NIH has formed the quate. For more controversial applications of gene Human Gene Therapy Working Group in part to therapy involving germ line alterations, wider fill this vacuum, but there are potential questions public discussion, open goal setting, and greater of conflict of interest because NIH is also the pri- government oversight may prove necessary to mary sponsor of biomedical research. Assessment avoid undue controversy and assure prudent pub- of public policy on goals for research, including lic policy. 40 • Human Gene Therapy—Background Paper

PAYMENT society. Several issues relating to genetics, such If gene therapy were to become incorporated as practices in a particular laboratory or individ- into routine medical practice, the Federal govern- ual patient-physician decisions, must be made ment might become involved in paying for its use. locally. Other issues of national importance, such As long as gene therapy is experimental, most as research policy, health policy, and civil rights, costs will be borne by research funds. Typically, may require attention by the Government and in- as a therapy is used more widely, funding be- ternational agencies. comes much more complex. Many regulatory Careful public policy decisions about novel tech- decisions are made about reimbursement at the nologies require an educated public. Federal agen- Federal and State levels, and individual insurers cies have been directly involved in educating the make reimbursement decisions that are subject public about gene therapy, through congressional to State and Federal regulations. hearings such as Human Genetic Engineering held Medicare reimbursement of gene therapy might by the Subcommittee on Investigations and Over- apply, for example, to those instances (probably sight of the House Committee on Science and quite rare) involving people over age 65 or who Technology in November 1982, symposia such as suffer from chronic kidney disease that could be the Public Forum on Gene Therapy sponsored by treated by gene therapy (polycystic kidney dis- NIH in October 1983, and publications such as ease is a dominant trait that leads to kidney fail- Splicing Life issued by the President’s Commis- ure, but is not now a candidate for somatic cell sion for the Study of Ethical Problems in Medi- gene therapy because the gene has not been iden- cine and Biomedical and Behavioral Research. tified and its mechanism of causing disease is not Several scientists have expressed concern that understood). the nuances of genetic technologies, such as the Medicaid is joint State and Federal health pro- distinctions between somatic and germ cell manip- gram that pays for medical services provided to ulations, may not be completely understood by indigent individuals. Medicaid reimbursement the public (Baltimore, D., in Friedmann, 1983, p. would involve both State and Federal policy, and 59). One basis for such concern is the experience might be used to pay for gene therapy of pediatric with the early debates about the safety of recom- patients in indigent families. binant DNA, when laboratory research involved precautions and preservation of detailed records Little has been written about how to pay for on laboratory safety of recombinant DNA work gene therapy. If other medical technologies are that were considered onerous by some scientists taken as examples, early costs are likely to be rela- (Weissmann, 1981). Rancorous public debates tively high, and drop as clinical experience and occurred before the City Council of Cambridge, technical innovations accumulate. Decisions will Massachusetts, and other places about whether be made about applications to specific disease en- certain recombinant DNA research should be per- tities rather than for gene therapy in general, and mitted (Wade, 1984). While recognizing the need there will likely be regional and institutional varia- for caution in research on recombinant DNA, tion among payers as to which applications are some believe that public concern led to overly reimbursable. Mechanisms of payment could stringent regulation triggered by baseless fears. range from complete public subsidy to total pay- One scientist noted, “It seemed that we had lost ment from personal income at each stage of de- track of the serious scientific and health con- velopment. If gene therapy proves successful in siderations and were operating in a climate of its early applications, more attention will need to hysteria–some of which passed for responsibil- be devoted to sources of payment. ity” (Leder, 1984). Public education is, many believe, the best solu- PUBLIC EDUCATION AND DISCUSSION tion to misapprehensions about genetic technol- The high level of interest in topics relating to ogies (Beckwith, 1984; Capron, 1984a, b). In- genetics suggests that mechanisms need to be decreased public education was designated a high veloped that permit discussion at all levels of priority by President’s Commission, and was in- The Federal Role in Gene Therapy . 41

eluded as the first of the major functions of any tory apparatus is suited to resolving such di- Federal agency overseeing the development of lemmas. Public debate can air differences, but genetic technologies (President’s Commission, should not be expected to eliminate them. 1982, pp. 82-84). The consensus on a need for In addition, there is a danger of gratuitous ad- public education does not, however, necessarily ditional regulation that would impede the devel- imply agreement that public education is primar- opment of legitimate human applications of ily a function of a Federal oversight body (H. I. genetics if new agencies are created, or overly Miller, 1984). stringent regulations imposed 0-I. I. Miller, 1984). Equitable social policy is another reason to fos- Finally, public debate cannot and should not inter public discussion. The governmental role in tervene in the decisions best made by individual developing, regulating, and applying gene ther- patients and the health professionals who provide apy is crucial, as noted in other sections of this care. Personal choice is a value that should be con- Background Paper. Informed public decisions strained as little as possible in establishing pub- presuppose not only adequate knowledge, but lic policy. also a process for ensuring that all views are fairly represented. FAIR DISTRIBUTION OF BENEFITS AND COSTS The need for wide public discussion of human The costs and benefits of gene therapy are uses of gene therapy and other genetic technol- uncertain because the technology is in its infancy. ogies has been noted by religious groups (World If gene therapy becomes a part of routine medi- Council of Churches, 1982; National Council of cal practice, however, then many issues relating Churches, 1984), by the President’s Commission to distribution of costs and benefits may arise. (President’s Commission, 1982), by ethicists and In general, these would be similar to those raised scientists (Grobstein, 1984), and in congressional by other medical technologies: payment, informed hearings (Gore, 1982). Opinion on this issue ap- consent, and fair access. Fair distribution of costs pears to have converged from many quarters, and benefits would be one of the considerations involving scientists, ethicists, politicians, and in reimbursement decisions mentioned above. It religious leaders, and resulting in what one ob- may fall to government to rectify reimbursement server has called an “amazing consensus” about decisions that do not provide equal access to all the need for continued oversight and discussion social sectors and ethnic groups. Access to gene at the Federal level (Nightingale, 1984). The func- therapy by the indigent or by minorities especially tions of such discussion include definition of goals, prone to certain genetic diseases, for example, identification of public policy issues, inclusion of might prove of special concern. conflicting views held by different constituencies, Decisions made now about research funding and consideration of short- and long-term con- will also influence the future distribution of sequences of genetic interventions of concern to various scientific, medical, religious, and con- benefits from gene therapy. Because different sumer groups. genetic diseases are more common in some racial groups, decisions about which diseases to in- There are some potential problems that even vestigate can be expected to influence the later an effective Federal forum for discussion may not availability of gene therapy or other treatments accomplish, however. It is doubtful that any com- among such groups. Neglect of hemoglobin dis- mission can resolve the differences that emerge orders, for example, would be of more concern from moral and social plurality in the United to Blacks and those of Southern Mediterranean States. For example, what conditions should be extraction than to other Caucasians. Federal deci- treated by gene therapy? Disorders such as bald- sions about which diseases are addressed in ness or short stature that are considered minor genetic research thus have potential distributional annoyances by one person might merit somatic consequences, and the large share of genetic re- 16 gene therapy as judged by another. No regula- search supported by the Federal Government makes such decisions important in determining 18Nelther of these conditions is sufficiently. understood to be a candidate for somatic cell gene therapy. They are mentioned only which populations may eventually benefit from to illustrate a point, not to indicate technical feasibility. available technologies.

38-803 0 - 84 - 4 , ~L ~ 42 . Human Gene Therapy—Background Paper

PROTECTION OF INDIVIDUAL RIGHTS not give consent for treatment or participation Some individual rights protected by the Federal in experiments. The problem of surrogate in- Government may be influenced by gene therapy, formed consent is especially likely for gene ther- as by any new medical technology. Any threat to apy, because many genetic diseases primarily af- such rights is, however, more likely to derive feet children or cause mental incapacity in adults. from new diagnostic techniques of genetic testing There are special guidelines for IRB’s to consider than from gene therapy. Maintaining the privacy in approving research protocols that involve of genetic diagnostic information about disease children (Code of Federal Regulations, 1983). risks is likely to be a much larger problem for Uncertainty about informed consent can act as individuals’ rights than performing gene therapy an impediment to research on the one hand, and because: 1) more people will be affected, 2) more may leave some patients insufficiently protected information will be generated by diagnostic tech- on the other. Some states are drafting legislation niques than therapeutic interventions, 3) the dis- to deal with the problem (Andrews, 1984a). State eases for which genetic risk factors might be and local initiatives may eventually clarify the assessed are common and have large economic legal status of surrogate informed consent, but, consequences for employers and insurers, and 4) in the interim, responsibility for monitoring the problems in protecting individual rights for gene informed consent process for research participa- therapy are quite similar to the problems arising tion will fall to IRB’s and the courts. from other therapies, while genetic diagnostic technologies may make much more information Case histories available of a new type. These issues are briefly addressed in appendix B. IN VITRO FERTILIZATION Some lessons from Federal policy relating to re- Knowledge that a person has undergone gene search and clinical applications of in vitro fertiliza- therapy should be accorded the same privacy tion (IVF) may be applicable to the development safeguards applied to other medical information. of gene therapy technologies. In vitro fertilization In addition to ensuring the privacy of genetic in- is the process of obtaining sperm and eggs from formation, including medical information about donors, uniting the gametes in the laboratory, and gene therapy, the Federal Government has ac- implanting the products of fertilization in a woman’s cepted a role in protecting the interests of re- womb. This technology was developed in the search subjects. Such protections include IRB’s 1950s, and first successfully applied to humans and, in the case of gene therapy, the RAC at NIH. in 1969. Improvements in fertilizing eggs in the FDA oversight also includes attention to informed laboratory led to the first human applications of consent of participating patients. in vitro fertilization a decade later: Louise Brown, A few weaknesses persist in the present meth- a normal infant conceived using in vitro fertiliza- ods of research subject protection. Children and tion, was born on July 25, 1978. She has been fol- mentally incompetent patients cannot consent to lowed by more than 700 pregnancies resulting treatment because they cannot understand the from in vitro fertilization and embryo transfer consequences of such consent. The process of in- (Hodgen, 1984). formed consent requires different standards in The primary intent of those using in vitro fer- different court jurisdictions (see app. B and An- tilization in humans is to permit infertile couples drews, 1984a), but all standards involve a com- to have children (Hodgen, 1984) although other petent patient or surrogate decisionmaker who applications are technically possible. can rationally balance risks and potential benefits. In cases of disagreement with physicians or other In vitro fertilization is related to gene therapy health professionals, families often are involved because, for technical reasons, attempts at germ in making decisions in the best interests of the line genetic alterations are most likely to be at- patient. In some instances, especially when there tempted on early embryos. Germ line gene ther- is disagreement between medical professionals apy would involve either extraction of a fertilized and families, it is not clear who can and who can- embryo from a woman (before the embryo had The Federal Role in Gene Therapy 43 implanted in the uterine wall) or, more likely, in not to be implanted back into prospective vitro fertilization either immediately preceded or mothers, followed by addition of genetic material. Avail- measures were taken to ensure that possi- ability of in vitro fertilization is thus a precondi- ble risks to the public were disclosed, tion for successful germ line gene therapy (Ryan, only gametes from married couples were 1983) and so policy affecting in vitro fertilization employed if embryos were implanted in pro- practices will also affect germ line gene therapy. spective mothers, and, most importantly, approval was obtained from the EAB, in ad- Even if in vitro fertilization were not directly dition to IRB review, before commencing. related to gene therapy, the history of Federal policy on it would still be of interest because it is The findings of the EAB have never been ac- a controversial biological technology analogous cepted by a Secretary of HHS (or HEW), the EAB to gene therapy in some respects. A brief review has been disbanded, and no Federal grants have of decisions made about in vitro fertilization may been approved for research on in vitro fertiliza- highlight potential pitfalls that could also occur tion. The NIH authorization bill from the 98th in connection with gene therapy. Congress, as passed by both houses and vetoed There has been a de facto moratorium on Fed- by the President, would have mandated a further erally sponsored research on human in vitro fer- 3 year moratorium on human fetal research, and tilization in the United States since 1975. There the new congressional bioethics board would are nonetheless at least 60 centers and 200 pro- have undertaken a study of it (Conference Report, grams offering it in the United States (Abramo- 1984). The moratorium on human fetal research witz, 1984; Hodgen, 1984). The research leading will continue, however, until an EAB that could to these early efforts was performed primarily approve it is reconstituted by the Secretary of in the United Kingdom and Australia. American Health and Human Services. centers have adopted the technology developed The Federal moratorium on research in the in other nations, or have treated patients using United States did not prevent the development private moneys paid by patient fees. of in vitro fertilization technology or its clinical Congress imposed a temporary moratorium on application, although its development has prob- Federally sponsored human in vitro fertilization ably been somewhat slowed (Abramowitz, 1983). research in 1973, after NIH received its first re- There is some concern that the technology has quest for a grant for fetal research. The 13 month developed with less than usual Federal oversight, moratorium was technically lifted in 1975, when and that some desirable steps, such as testing in guidelines proposed by the Ethics Advisory Board non-human primates, have been skipped in the (EAB) of the Department of Health and Human transition from experiments in lower mammals Services (then the Department of Health, Educa- to human clinical applications (Ryan, 1983). Ex- tion, and Welfare) were published. The guidelines periments have not been subject to the NIH peer sanctioned carefully constrained research, pro- review process, and may have “circumvented sys- vided that strict procedures were observed, in- tematic accumulation of knowledge” (Ibid., p. 152). cluding: The Federal Government may have lost some ability to monitor and control the technology by the intent of the research was to improve un- failing to sponsor research (Ibid., pp. 151-153) or derstanding of fertilization and assess risks, at least to provide a mechanism for Federal over- the information could not be obtained by sight. Furthermore, the technology developed in other means, spite of the lack of a consensus about its moral informed consent, including disclosure of acceptability (Ibid., p. 153). risks, was obtained, and other regulations on human subjects research were observed, The unusual development of in vitro fertiliza- embryos beyond the fourteen-day stage of tion research is exemplified by one technique of development were excluded if embryos were in vivo fertilization of an egg in one woman fol- 44 . Human Gene Therapy—Background Paper

lowed by transfer of the embryo to another. The suggest that such discussion necessarily take place technique permits obtaining the fertilized egg through the Federal Government) (Fletcher, without subjecting the donating woman to a ma- 1983b; Grobstein, 1984; Nightingale, 1984). The jor surgical procedure. This technique has been lack of a forum for conducting public debate developed with corporate funds in the United holds also for fetal research and in vitro fer- States, and those who sponsored the research tilization. have applied to patent some of the instruments Human gene therapy may be less attractive to involved, as well as the process itself (Annas, 1984; corporate investors than in vitro fertilization re- Chapman, 1984). A patent for a medical proce- search. The investment incentives for gene ther- dure is unusual, although not unprecedented apy are diminished by the relatively small num- (Brotman, 1983); if granted, it would give the ber of individuals with any given genetic disease. sponsoring corporation the ability to limit the ap- This restriction does not hold, however, for all plication of surrogate embryo transfer to those diseases and does not necessarily preclude the de- who obtained a license. Such limitation might in- velopment of profitable products. Gene therapy crease costs and diminish access to the technol- applicable to certain diseases such as sickle cell ogy, but might also permit enhanced quality and anemia or cystic fibrosis might have a market controlled diffusion of the procedure. One of the large enough to justify corporate interest. In ad- arguments used in favor of patenting the proc- dition, a general approach to gene therapy that ess is that the research was privately sponsored, could apply to many genetic disorders might be and so the investors merit a return on their in- patented, analogous to the Cohen-Boyer patent vestment (Chapman, 1984; Annas, 1984). for recombinant DNA, or kept as a trade secret. The example of in vitro fertilization technology The incentives for private investment may thus shows that techniques developed in other coun- be weaker than for in vitro fertilization, but may tries can be imported, and such applications made nonetheless be sufficient to induce corporate re- available in the United States, even in the absence search and development. of Federal research support. Widespread clinical There is a prominent regulatory difference be- use of in vitro fertilization also shows that tech- tween in vitro fertilization and human gene ther- nologies whose appropriateness is seriously ques- apy: in vitro fertilization is not clearly under the tioned may nevertheless enter clinical practice jurisdiction of FDA or NIH, but human gene ther- without extensive Federal oversight or regulation, apy is subject to both. Gene therapy is likely to and in the absence of pervasive public discussion. involve new pharmaceutical products, and hence Gene therapy is different from in vitro fertiliza- be regulated by FDA, because experiments will tion because there is no moratorium on gene ther- involve introduction of new genes or modified apy research, and so the bulk of research is viruses into human cells or into patients. In con- funded, like other biomedical research, through trast, in vitro fertilization is more a process than the Federal government. Such research neces- a product. Further, in vitro fertilization is applied sarily falls under the oversight purview of NIH, to correct infertility, a problem that is not neces- and consequently the RAC and its Human Gene sarily considered a disease or injury, and thus Therapy Working Group. There are many agen- may not fall under FDA purview. In vitro fertiliza- cies with jurisdiction over gene therapy, including tion has passed through the early phases of tech- local IRBs, NIH, and the FDA (for specific prod- nological development to clinical application with ucts). These bodies are now preparing to deal little regulation or Federal oversight, but human with the incremental medical advance embodied gene therapy is receiving extensive public scru- in somatic gene therapy. Review by these bodies tiny and Federal oversight despite its technologi- may not be adequate for extension of gene ther- cal infancy. apy to reproductive cells. Several authors refer to the need for national public discussion of the EARLY ATTEMPTS AT HUMAN GENE THERAPY greater ethical and social implications raised by The Rogers Cases.—Between 1970 and 1973, germ line alterations before commencing such re- Dr. Stanfield Rogers, an American, assisted a Ger- search (although the authors do not uniformly man physician in treating three sisters with the The Federal Role in Gene Therapy 45

genetic disease arginemia. The sisters were in- In contrast to the Shope virus experiments, fected with the Shope papilloma virus, which had there was a consensus that Dr. Cline’s experi- activities that physicians believed might supplements were premature and unethical. Dr. Cline ment an enzyme activity missing in the three girls. resigned his division chairmanship, and the NIH The treatment was unsuccessful. terminated two grants, To prevent future abuses, NIH also added several requirements, including The Shope virus experiments were performed the need to submit an assurance of compliance before ethics review boards, IRB’s, or IBC’s ex- with human subjects safeguards, prior review by isted. The experiments were discussed openly, al- the local IBC and NIH of all recombinant DNA ex- though much of the debate about their propriety periments, and inclusion of the NIH report of the did not take place until after the clinical trial. The events to the review groups for his subsequent debate centered on whether there was sufficient new applications for NIH grants (Talbot, 1982). evidence to anticipate patient benefit, and The special sanctions were in effect until May whether the intervention had been undertaken 1984. at a time when it could best benefit the sisters (Fletcher, 1983). The ethical debate about the The issues raised by the Cline experiments are Shope virus experiments is thus unresolved, al- likely to recur in any debate about the propriety though it is clear that no institutional or legal of human gene therapy, and so a summary of the precepts were violated. justifications and objections is instructive, followed by a review of Federal policy in the Cline The Cline Cases. —Martin Cline, an American clinical trials. scientist and physician primarily working at the University of California at Los Angeles (UCLA), There were several justifications for undertak- became the first investigator to attempt gene ther- ing clinical trials of human gene therapy, as noted apy using recombinant DNA in 1980, when he at- in previous sections. Those used to justify the ex- tempted to treat two patients who had thalassemia. periments involving the patients with thalassemia One patient was treated in Italy, and the other included: in Israel. Dr. Cline withdrew samples of bone mar- The condition was irreversible. row from each of the patients, treated them with Alternative therapies were unpleasant, ex- DNA containing a normal hemoglobin protein pensive, led to deleterious side effects, and gene, and restored the treated bone marrow cells did not cure the cause of the disease, but to the patients. The process for returning the merely diminished its effects (Wade, 1980; bone marrow involved killing a portion of the Cline, 1982). native cells by radiation, so that the treated cells The Human Subjects Protection and Institu- would have a location in which to grow. The ex- tional Biosafety Committees had been consid- periment was the first attempt at somatic gene ering the proposals in the period between therapy using recombinant DNA techniques. May 1979 and July 1980 without approving At the time the experiments were performed, or disapproving them. There was also an approval by the local review committees was apparent logjam, with the Human Subjects pending. The gene therapy experiments were at- Committee requiring that the IBC approve the tempted on July 10 and July 15, 1980, and Dr. protocol before it would assess it, and the IBC Cline’s proposal to the UCLA Human Subject Pro- awaiting the review of the Human Subjects tection Committee was disapproved on July 16 committee. Attempts to refer the matter to (Talbot, 1982). Dr. Cline had prior approval for the RAC were thwarted because NIH refused a gene therapy experiment by the local board in to consider the proposals, reasoning that the Israel, but not for the one, involving recombinant human subjects aspects were much more im- DNA, that he actually performed.17 ———— ‘The Israeli board had approved insertion of genetic material that not add to the danger of the experiments, because the genes tend included the normal hemoglobin protein genes. Dr. Cline contends to combine in the cell even if they are not in recombinant form that the use of recombinant form was a technical detail that did i~hcm first inserted (Cline, 1982), 46 . Human Gene Therapy—Background Paper

portant than the recombinant DNA technol- his collaborators as they were received; the ogy itself (wade, 1981a). investigators knew that there were objections The Israeli experiments were approved by to starting the experiments (Wade, 1980). three committees in Israel, although not for the protocol involving recombinant DNA The issues raised by the controversial Cline ex- (Wade, 1981b). periments point out the importance of Federal research policy decisions. The research in question Those who criticize the Cline experiments do was funded, in large part, through NIH, and the not disagree with these facts, but interpret them review procedures for application to humans differently, and add the following considerations: were specified by the NIH. The sanctions rendered The patients selected had an irreversible dis- against Dr. Cline were imposed by the Depart- ease, but were not in a terminal state (as ment of Health and Human Services, based on NIH called for in the protocol). They were alive review; many believe that one reason that the more than two years after the experiments sanctions were relatively stringent was because were undertaken, despite lack of any bene- of congressional concern about previous laxity on fit deriving from the experiments (Cline, the part of NIH in punishing those who violated 1982). research guidelines (Sun, 1981; Wade, 1981 b). The human experiments were never pub- Some of the consequences of the Cline experi- lished and were based on other animal ex- ments are less tangible than receipt or denial of periments that had not been peer-reviewed grant applications. Many believe that the Cline ex- at the time (and about which there are dis- periments are one reason for the current promi- agreements regarding interpretation) (Cline, nence of gene therapy in the debate about recom- 1982). binant DNA. Critics of the technology may cite There were no data on the safety of the pro- Dr. Cline’s experiment in arguing for tighter re- cedure, because directly analogous experi- straint on scientists because they cannot be ments had not been attempted in animals trusted to behave responsibly (Wade, 1980). (Williamson, 1982). Dr. Cline personally decided to deviate from A de facto moratorium on somatic and germ his protocol, using a recombinant molecule line gene therapy has reigned since 1980. The rather than separated genes. While this deci- Cline experiments may have catalyzed formation sion may have been scientifically valid, Dr. of a consensus that the time was not ripe for such Cline failed to notify the Israeli committees, experiments (Walters, 1982), and the opprobrium committees in the United States, and even the directed at Dr. Cline may have made scientists patients and his collaborators, of his decision aware of the public sensitivity of the issue. The to use recombinant DNA (Wade, 1981a; Cline, case, above all, highlighted the changing milieu 1982). for making decisions about human subjects in The ambiguities about which committee clinical research, and the growth of research should first approve the protocol had been oversight by the Federal Government. The results resolved by the time the experiments took have been summarized by John Fletcher, a spe- place. The decision to refrain from using cialist in bioethics at NIH: recombinant DNA removed the need for IBC approval, leaving only the local Human Sub- Dr. Rogers treated the German sisters before jects Protection Committees to approve the prior group review became institutionalized. Dr. protocol (Wade, 1980). Cline, on the other hand, attempted to bypass that safeguard by withholding information from those The Human Subjects Protection Committee who passed judgment on the wisdom of the ex- in the United States was not dallying, but periment. The censure falling on Dr. Cline be- awaiting expert comments from four con- cause of his deception indicates the strength of sultants to assess the scientific basis of the prior group review as a structure to guide somatic experiments. The process took time, and the gene therapy when it becomes feasible (Fletcher, comments were passed. on to Dr. Cline and 1983b). Conclusion 47

Conclusion

The first realistic applications of human gene federally sponsored clinical trials should be re- therapy will be closely scrutinized by both the ferred to the RAC at NIH for approval, and may public and the Federal Government. Civic, reli- also be reviewed by FDA. gious, scientific, and medical groups have all accepted, in principle, the appropriateness of gene The consensus about the propriety of somatic therapy of somatic cells in humans for specific cell therapy does not extend to treatment for genetic diseases. Somatic cell gene therapy is seen traits that do not constitute severe genetic dis- as an extension of present methods of therapy eases, and does not encompass germ line gene that might be preferable to other technologies. therapy in humans. The question of whether Whether somatic cell gene therapy will become germ line gene therapy should ever begin is now a practical medical technology will thus depend highly controversial. The risk to progeny, rela- on its safety and efficacy, and the major question tive unreliability of the techniques for clinical use, is when to begin clinical trials, not whether to and ethical questions about when to apply it re- begin them at all. The quality that distinguishes main unresolved. The question of whether and somatic cell gene therapy most strongly from when to begin germ line gene therapy must there- other medical technologies is not technical, but fore be decided in public debate informed by tech- rather the public attention that is likely to attend nological developments. its commencement. If gene therapy develops as a viable new medi- Federal oversight mechanisms for research and cal technology, issues will emerge regarding who clinical application of somatic cell therapy are is to pay for it, how to assure equitable access already in place, and enforcement of the man- to it, who is qualified to perform it, how to regu- dated approval processes has already taken place late its proper use, and which diseases merit its in one instance, the breach of NIH guidelines application. Many Federal agencies, including NIH, perpetrated by Dr. Martin Cline. Committees ex- FDA, and health care payers, will be involved in ist at local institutions to monitor protocols for such issues if the technology becomes part of human subject protection, and all proposals for standard medical practice. 48 . Human Gene Therapy—Background Paper

Technical note 1

DNA function Excision/ligation is most similar to an editing process, and it is necessary because many genes contain Deoxyribonucleic acid (DNA) is a long, double more nucleotide bases than are necessary to code for stranded, helical molecule that contains building the number of amino acids the finished protein will blocks (nucleotide bases) in a sequence which encodes contain. Within a given gene there are two types of instructions for all the metabolic processes in the regions: “exons,” or expressed regions, and ‘(in= human body, These range from growth and develop- trons, ” or intervening regions. Exons contain the in- ment through specific biochemical interactions information that precisely directs the assembly of the volved in the digestion of food and synthesis of new protein product, that is, the sequence of amino acids molecules. DNA regulates its own expression and con- added to the growing protein chain during translation. trols the production of proteins: structural proteins, Introns, on the other hand, are the regions found be- used to build the framework of cells, organs, and tween expressed regions. Their function is unclear; tissues; and enzymes, used to perform biochemical one hypothesis is that introns are involved in regulat- activity. There are two major processes involved in ing gene expression (which includes turning genes on putting this information to use in the body-transcrip- and off and controlling the number of mRNA mole- tion and translation. cules produced, and therefore the amount of gene Transcription is the simplest of these two proc- product). The original mRNA transcript is thus esses. It consists of making an RNA (ribonucleic acid) trimmed and spliced by specific enzymes and trans- copy of the DNA. This copy is then used to transport ported from the nucleus to the cytoplasm, where it the instructions from the DNA to the protein build- is decoded or translated into protein (see diagram). ing apparatus in the cell, outside the nucleus. This RNA Methylation refers to the process of attaching a small copy of the DNA is called ‘(messenger RNA” (mRNA) molecule (a methyl group, or a carbon with three at- because the message it carries from the gene allows tached hydrogens, CH3) to the backside of one of the the construction of the specified protein. nucleotide bases in the mRNA. The reason for this is The process by which the mRNA is formed is very not completely understood, but it is thought that simple, taking advantage of the unique properties of methylation alters the mRNA in such a way that some nucleic acids (DNA and RNA). The double stranded enzymes responsible for degrading it will not do so DNA molecule separates, or unzips, at which point spe- as quickly as they otherwise might. Methylation pro- cific proteins present in the nucleus (enzymes) recog- vides a method for controlling the longevity of mRNA nise precise signals present in the DNA (e.g., sequences molecules; it is desirable for some to be very short of nucleotide bases, such as TTAA) and attach to the lived (where only a small amount of the encoded pro- DNA at those sites. One enzyme (called an RNA poly- tein is required, as for an enzyme briefly needed) and merase) then moves along the DNA molecule, con- for others to last longer (e.g., the mRNA coding for structing an mRNA molecule that has a complemen- hemoglobin production in red blood cells, which live tary sequence of nucleotide bases (i.e., where there for about three months in the bloodstream). is an A in the DNA, the mRNA polymerase will add The second major process involved in making use a T to the growing polymer). The end result is an RNA of the information encoded in the DNA is translation, molecule that is a mirror image of the DNA region, This takes place after mRNA is transcribed from DNA or gene, which can then direct the assembly of a spe- and then transported from the nucleus into the cyto- cific product. plasm. In translation the information encoded in Before this mRNA molecule is used to assemble a mRNA is decoded (translated) into protein by ribo- protein in the process of translation, however, it must somes. Ribosomes are complex structures within the first be subtly modified; trimmed and tucked, as it cell that serve as the sites of protein synthesis, and were, so as to more precisely fit its function. There they are composed of a number of different proteins are several of these trimming processes and they are combined with several different RNA molecules. On known altogether as “mRNA processing” or “post- ribosomes, amino acids are joined one at a time to transcriptional modification”. Our understanding of form a growing polypeptide chain. These individual these processes is incomplete, but the two best known amino acids are brought to the ribosome by transfer are “excision/ligation” and “methylation. ” RNAs (tRNAs). Each different amino acid is brought Technical Note 1 49

Gene Splicing

SOURCE: Office of Technology Assessment, adapted from Stanbury, et al., 1983, to the ribosome by a specific tRNA, which has a recog- master DNA region (gene) in the nucleus. Proteins pro- nition site at one end specific for that amino acid, and duced by translation of messenger RNAs can begin a recognition site at the other end specific for the their lives as enzymes involved in specific chemical mRNA coding sequence that calls for the particular reactions in the cell, or the proteins can be moved amino acid. These specific coding sequences in mRNA around or modified so that they become part of the occur in a linear chain, and the amino acids added to surface of the cell, part of the cell’s skeleton, or per- the growing polypeptide as the mRNA moves along the form some other function. ribosome reflect the linear sequence encoded in the 50 . Human Gene Therapy—Background Paper

met I met ala cys

mRNA—AUG GCA UGC CCU AUG GCA UGC CCU AUG GCA UGC CCU

Complete protein

Protein

UAA AUG GCA UGC CCU AUG GCA UGC CCU AUG GCA UGC CCU

tRNA translates from mRNA into protein, with ribosomes acting as the conveyor belt to allow this process SOURCE. Office of Technology Assessment. Technical Note 2 51

Technical note 2

Genetic engineering techniques: parent cell divides. The genetic information encoded cloning and vectors in plasmid DNA often determines specialized characteristics of the bacteria, such as resistance to an- There are several techniques of genetic engineer- tibiotics. Their small size and simplicity have made ing that are fundamental to efforts at human gene them handy tools for the precise duplication and de- therapy. The most basic of these is cloning, or mak- livery of genetic information. ing multiple copies of a specific single gene. Once a Some plasmids can be injected into the cells of higher gene has been cloned, it may be made in as many animals where they replicate or integrate and pass copies as desired (and thus easily studied), or moved from cell to cell as the cells divide. They are widely from place to place through the use of specialized used in copying and multiplying genes because the agents known as vectors. There are several types of special characteristics (e.g., antibiotic resistance) are vectors; viruses (bacteriophages, or phages), plas- easily engineered. These can he used to selectively pro- mids, or transposable elements. mote the growth of cells that contain the plasmid, and Cloning involves several different steps. First the thus also the desired genes. gene of interest must be identified; if it exists in only Phage.—Phage (or bacteriophage) are viruses that one copy per haploid genome (as with single gene, or infect bacteria, commandeer the bacterial machinery, Mendelian defects) then that one copy must be se- and use it to translate the genetic information con- lected from perhaps as many as 100,000 other genes— tained in the phage into phage products. Normally this a formidable task. As daunting as this problem is, how- leads to an infected bacterium producing phage off- ever, there are some elegantly simple solutions. spring, but if the genes for building phage are replaced The most favored of these is to identify the messen- with a gene of interest to researchers, then the in- ger RNA used by ribosomes to assemble the protein fected bacterium will produce copies of that gene in- of interest. Although mRNA is short-lived and no- stead. Phage can thus be used in much the same way toriously delicate, this can often be done. From this that plasmids can, to make multiple copies of a given mRNA a complementary DNA (cDNA) molecule can be gene. The choice between using phage or plasmids as synthesised, labeled with a tracer (radioactivity or a cloning vectors is based on the ease with which genes dye) and then used as a probe to identify the gene. of different sizes or composition can be cloned with If an mRNA cannot be identified, then it is possible the different methods, and the advantages of different to start with the protein product itself. This protein screening methods that can be used with the different can be analysed and its amino-acid sequence deter- vectors. mined. The amino-acid sequence can be used to Transposable Elements.—Transposable elements deduce the nucleotide base sequence of the gene en- (transposons) are relatively small molecules of DNA coding the protein. A DNA molecule can then be syn- that can insert themselves into the genome of the host thesised and used as a probe to locate the relevant organism and move from site to site within it. Their gene with its associated control sequences. origin is uncertain, but they seem closely related to Once identified and located, special enzymes (re- some viruses. They have been called infectious or striction endonucleases or restriction enzymes) parasitic DNA and behave in some ways very much make it possible to isolate the entire intact gene and like infectious agents. insert it into the appropriate vector. Plasmid (circular Genes of interest can be inserted into a transposable DNA molecules found in the cytoplasm of bacteria element, and thus be incorporated into the host such as E. coli) or virus (phage) vectors make it possi- genome along with the transposable element at spe- ble to produce enormous numbers of copies of the cific sites. Although there are no transposable ele- gene of interest. ments presently. in use in human cells, they have been Plasmids.—In addition to the genetic information successfully used to “treat” genetic defects in fruit flies required for the existence of a simple bacterium, of the genus Drosophila (Rubin and Spradling, 1982; which is contained in its own genes, on its own Spradling and Rubin, 1983). A mammalian equivalent chromosome, many bacteria also carry in their cyto- to a transposable element would be a welcome dis- plasm small circular molecules of DNA that replicate covery, as it could be used to control points of inser- on their own. These are called plasmids and any num- tion into a human genome very precisely. Some viruses ber of them, from none to hundreds, can be found being considered as vectors for human gene therapy in individual bacteria. They are transmitted to progeny have similarities to transposable elements, including cells with the cytoplasm (hence the name) as the precise insertion sites. 52 . Human Gene Therapy—Background Paper

Technical note 3

Violating species barriers unusual. This is emphatically not the case in nature. Hybrids are well known in higher organisms, where The majority of gene-therapy cases in humans would admittedly many are sterile (e.g., mules, resulting from involve transplanting human DNA from one individ- a mating between a horse and a donkey). However in ual to another. In the forseeable future, research on some groups hybrids between species are so common and application of these techniques (or capabilities) is that distinct populations of these intermediate forms unlikely to use genes from an animal species to treat may exist along the distribution boundaries of neigh- human genetic diseases. It is more likely that tech- boring species (Endler, 1977; Mayr, 1963, 1970). In niques involving the transplantation of genetic mate- these hybrid populations it is very difficult to assign rial from one animal species to another would be use- an individual to either of the parent populations, ful in agricultural or industrial applications; work of which might themselves be quite easily distinguished this kind has already been performed (involving hu- from one another. Hybrids are more common in less man genes being moved into certain agricultural ani- advanced vertebrates, such as amphibians or fish, and mals). The most far- reaching experiments of this sort there are even cases known where new species have are designed to increase understanding of mechanisms been formed by hybridization between two previously of genetic control and gene regulation. * This research existing species (White, 1978). In other situations will enhance scientists’ ability to work with the genes species “boundaries” are so permeable that relatively of individuals within a species, and thus decrease the widespread movement of genetic material from one need to transfer genetic material between species in species to another exists, a phenomenon called intro- future therapeutic endeavors. The question has gression. In plants, hybridization is so common that arisen, though, as to whether such work should be one leading expert (Raven, 1980) has concluded that completely avoided or terminated because of an in- it is almost useless to talk of “species” and that the most herent danger or impropriety in “violating species important reproductive group is the local population, boundaries. ” A look at nature offers a useful or deme. To complicate matters further, some recent perspective. research offers tantalizing hints that horizontal trans- A species is a community of organisms that is repro- mission (between individuals of the same generation) ductively isolated from other such groups; that is, very similar to the sort contemplated in some types within a species there is interbreeding (exchange of of gene therapy have probably taken place between genetic material) among individuals and their off- distantly related species (felids, or cat-like creatures, spring, but none with individuals of other, different and primates) in the past (Benveniste and Todaro, species. The problems with this widely used defini- 1982; Lewin, 1984). Specialists today are therefore be- tion are several, and many of them are quite techni- coming increasingly interested in factors that keep a cal and esoteric. The most significant of these involve species together rather than in mechanisms that may the existence and frequency of hybrids, or “cross- serve to keep them apart (Paterson, 1981, 1982). breeds” between species. This is a useful approach in considering animal ex- If species are to be defined on the basis of reproduc- periments relevant to human gene therapy. The ques- tive isolation, a sort of “genetic quarantine)” then viola- tion changes from “When can we justify violating tions of this quarantine, hybrids, should be rare and species barriers?” to ‘(How much transmission of genetic material from one species to another can be tolerated before the integrity or separateness of the IThe study of oncogenes (genes whose expression is linked to cancer) has recipient species is threatened?” The answer is clear— in~ol~ed hundreds of transfers of genes between species. From them we have learned enormous amounts about the mechanisms of carcinogenesis and gene an enormous amount; far more than would ever be regulation. involved in any case of gene therapy. Technical Note 4 53

Technical note 4

Fertilization, implantation, and (chorionic villi) into the wall of the uterus as an- development chors. These fingers are made up of embryonic cells that manufacture hormones to support pregnancy; FERTILIZATION they also form the network of supporting tissues that When a sperm and egg (or ovum) meet, the sperm will eventually become the placenta, nourishing the penetrates the wall of the egg. The genetic material developing embryo, and later fetus. from the sperm and egg unite, and the process of uni- fying the genetic contents of sperm and egg is called DEVELOPMENT fertilization. The cell thus formed, containing DNA At the same time the primitive placenta is forming, from both sperm and egg, is called a zygote. The mass the cells that will later become the embryo, and then of cells in the earliest stages after fertilization is also fetus, become more distinct from those embryonic called a conceptus. cells that develop into the supporting structures The release of an unfertilized egg from a woman’s (placenta and protective membranes). By 2 weeks post- ovary is triggered by a burst of luteinizing hormone, fertilization the process of implantation is almost com- or LH, from the pituitary gland (located near the base plete, and differentiation of the embryo itself is be- of the brain). The released egg migrates from the coming more pronounced: at least two distinct classes ovary a short distance through the abdominal cavity of embryonic tissue can be identified. The third week and into the oviducts, or Fallopian tubes. The Fallo- sees the emergence of a group of cells called the pian tubes lead into the uterus, and are the usual site primitive streak that will eventually lead to the de- of fertilization after the sperm have migrated into velopment of the nervous system, which begins before them from the vagina through the uterus to meet the the end of the third week after fertilization. The descending egg. The developing conceptus then con- primitive streak is the first landmark that distinguishes tinues its descent through the Fallopian tubes into the the “top” from the “bottom” of the embryo. body of the uterus. The embryo rapidly continues to develop more defined features, including limbs, organs, ears and eyes. CELL DIVISION About 8 weeks after fertilization (7 weeks after im- The zygote begins to divide, first into two cells, then plantation) most of the basic tissues have taken shape. into four, then eight, and so on. During the earliest It is at this point that the embryo makes the transi- stages of development all the cells are more or less tion to a fetus, with most subsequent development tak- equivalent. Once more than 16 cells are present, how- ing the form of growth and specialization of organ ever, some distinctions between different types of cells function, rather than the formation of new organs. begin to appear. Quite small and difficult to detect at Highly complex systems, like the brain and nervous first, these differences become more pronounced as system, continue to develop long after the embryo has cell division and growth continue, and form the foun- become a fetus, and even after birth. dation for the later differentiation of tissues and organs. VIABILITY Different terms are applied to the developing orga- Viability is the term used to indicate that the fetus nism as larger numbers of cells accumulate. The proc- could survive outside the womb. The concept of via- ess of cell division is called cleavage. When enough bility played a central role in the Supreme Court deci- cells have accumulated (between 32 and about a hun- sion in Roe v. Wade, in which maternal rights with dred), the term morula is used. The following stage, respect to abortion were decided. The point at which when the cells arrange themselves around a central viability begins has been considered to be about the cavity, is called the blastocyst. About I week after beginning of the third trimester of normal gestation. fertilization the blastocyst attaches to the uterine wall This is subject to change, however, with innovation to continue further development. and progress in postnatal care. New techniques are proving to be efficient at preserving the lives of IMPLANTATION younger and smaller premature infants, and the trend Implantation is the term applied to the proc- promises to continue. The effect of these changes on ess by which the conceptus attaches to the wall the medical determination of fetal viability and its rela- of the uterus and begins to send fingers of tissue tion to maternal legal rights is not at all clear. 54 • Human Gene Therapy—Background Paper

Human Fertilization and Early Embryonic Development

Combined maternal & paternal chromosomes

ZYGOTE

Sperm nucleus

Egg nucleus

Nucleus of zygote — B Fertilization F First mitotic division

/ 2-cell stage 4 cell stage

terine wall

Invading trophoblast

Implantation starts

SOURCE: Office of Technology Assessment Technical Note 4 55

Implantation of the Embryo in the Wall of the Uterus

Vertical section: Human embryo, on about the 10th day, becomes embedded in the soft uterine wall. After about 2 additional weeks, the embryo wiII derive nourishment through a new placenta which wiII develop at the site of the attachment

Imbedded embryo forms site of placenta

Human Placenta

Maternal blood vessels ~

Umbilical cord 56 Human Gene Therapy—Background Paper

Fetal Position in the Uterus Umbilical cord

Embryo SOURCE: Office of Technology Assessment.

Human Embryonic and Fetal Stages

Head Jaws

Leg

15 weeks SOURCE: Office of Technology Assessment. —.—

Technical Note 5 57

Technical note 5

Hemoglobin disorders: a case study of These genetic defects are not located on a sex chromo- genetic disease some and usually require two faulty copies of the gene for the disease to manifest clinically. Hundreds of Inherited hemoglobin disorders are currently the thousands of people have only one faulty copy of the best studied and defined of all human genetic diseases. gene out of the allotted two, and thus are labelled They are probably the most common single-gene dis- heterozygous carriers of these diseases. An estimated eases in the world (Weatherall and Clegg, 1981). Be- 200,000 people with hemoglobinopathies are born an- cause of that, and because the blood- manufacturing nually, divided equally between sickle cell anemia and cells in bone marrow are so accessible, hemoglobino- thalassemia (WHO, 1982). The thalassemias are most pathies were presumed, until several years ago, to be common in Asia, and sickle cell is most common in the first candidates for human gene therapy. Africa. Among American blacks, about 8 percent carry Although innovative recombinant DNA technology sickle cell trait and one in 500 newborns have sickle has pinpointed the genetic defects responsible for dif- cell disease (Stern, 1973; McKusick, 1983; Bowman, in ferent hemoglobin disorders, recent experiments re- personal communication, 1984). vealing that the regulatory complexities in the manufacture of hemoglobin, and in gene regulation in Sickle cell anemia general, indicate that hemoglobinopathies will not be effectively treated until these processes are better un- Sickle cell anemia involves a variation in hemoglo- derstood and can be controlled (Anderson, 1984). bin structure due to substitution of one nucleotide on the beta globin gene, leading in turn to a substitution NORMAL HUMAN HEMOGLOBIN of the amino acid glutamate for valine (the normal sixth amino acid on the beta globin chain) when the All normal human hemoglobins are composed of two pairs of identical protein chains, forming a faulty gene is ‘(transcribed” and used to produce he- "tetramer”. Hemoglobin differs between the embryo, moglobin protein in the bone marrow cells. The he- fetus and postnatal human because genes coding for moglobin containing the faulty beta globin chains (Hbs) different protein chains are activated progressively is less soluble than normal hemoglobin and, under during development. Fetal hemoglobin (HbF), for ex- reduced-oxygen conditions, can form a crystal that ample, is composed of two alpha and two gamma distorts the red blood cells into shapes resembling chains while the adult version contains two alpha and either two beta (95 percent) or, much less commonly (3 percent), two delta chains (Orkin and Nathan, 1981). These complex regulatory changes in hemoglobin synthesis aid in transporting oxygen across the placenta, from mother to fetus. This is possible because embryonic and fetal hemoglobins have higher oxygen af- finities than normal adult hemoglobins. The two major types of single-gene hemoglobin diseases are sickle cell anemia and the thalassemias.

Red blood cells–normal and sickle cell SOURCE: Office of Technology Assessment.

38-803 0 - 84 - 5 , QL 3 58 Human Gene Therapy—Background Paper

sickles. These misshapen red blood cells are rapidly ALPHA THALASSEMIAS destroyed and become lodged in capillaries, leading Most alpha thalassemias involve gene deletion. “Si- to partial or total blockage of blood supply to parts lent carriers” (those showing no clinical symptoms) of the body. Pain and local-tissue damage results, espe- have one of the four normal alpha globin genes per cially in those organs with extensive capillary net- cell deleted. Those with alpha thalassemia “trait” have works such as the lungs, heart, kidneys, brain, spleen two genes deleted and usually show no anemia. “Hb H“ and hips. disease is associated with the deletion of three genes The blood of a person with two copies of the “sickl- (Kan, et al., 1975) and is characterized by mild to ing” gene consists primarily of HbS; this person is said moderate anemia. Homozygous alpha thalassemia in- to have “sickle cell disease” and generally has an ab- volves deletions of all four gene copies and results in breviated lifespan. The impaired circulation can lead severe anemia, accumulation of body fluid, and in- to anemia, pain in the joints, sporadic abdominal pain, trauterine death (Orkin, 1978). lung and spleen damage, ulcerations of the lower ex- tremities and acute episodes such as stroke, kidney BETA THALASSEMIAS failure, and heart failure (Bowman and Goldwasser, There are only two beta globin genes in the normal 1975). The clinical symptoms are extremely variable, however, and some people may remain completely human genome. If only one copy of the gene is af- free of serious illness. A person who possesses one fected, an individual is said to be heterozygous and faulty and one normal copy of the beta globin gene have beta thalassemia trait. Such heterozygotes are has “sickle cell trait” and has blood containing 20 to usually asymptomatic, except for occasional mild ane- 40 percent HbS. Such “carriers” typically exhibit little mia or slight spleen enlargement. If both genes are or no clinical symptoms of anemia and have a normal affected, the individual is homozygous and has the dis- life expectancy. ease beta thalassemia. Symptoms of the beta thalassemia disease include severe anemia, enlargement of the spleen, liver and heart, skeletal deformation, ab- Thalassemias normal facial features, and abbreviated life span. Other less common forms of thalassemia involve per- The thalassemias are characterized by decreased sistence of fetal hemoglobin, however, and therefore production of certain hemoglobin chains, There are constitute models for the study of the mechanisms re- several types of thalassemia named according to which sponsible for switching from fetal to adult hemoglo- globin chain is deficient. For example, in alpha thalas- bin synthesis during development. If better under- semia, little or no alpha globin is produced. The same stood, this process might be exploited clinically as a holds true for beta thalassemia, where little or no beta treatment for beta thalassemia in which fetal hemoglobin is produced. These are the most common forms globin synthesis could be “turned on” to compensate of thalassemia. for deficient adult beta globin synthesis. The decrease in globin production by the affected gene ranges from none at all (as in alphao- or betaO- thalassemias) to somewhat less than normal (as in Other unstable hemoglobins alpha +- or beta+- thalassemia). The clinical signs and There are dozens of mutant types of globin protein symptoms are extremely variable, especially among that replace either the alpha or, more commonly, the heterozygotes, ranging from none to serious anemia. beta chains in hemoglobin (Winslow, 1983). Many of Generally, the symptoms afflicting an individual these form unstable hemoglobins that deteriorate heterozygous for thalassemia are exacerbated under rapidly and cause anemia. Most are extremely rare, physical stress. Prolonged stress can exhaust the aux- with the exceptions of hemoglobin SC disease and he- illiary blood production mechanisms that are already moglobin S-thalassemia. These two disorders are being pushed to maintain normal hemoglobin levels. hemoglobinopathies that occur in patients who have The genetic defects underlying thalassemias are as one sickle cell gene combined with another mutant varied as the associated clinical symptoms. The im- gene–for globin C in one case and for thalassemia in paired synthesis of globin chains could result from the other. mutations grossly affecting the structure of a globin The unusual hemoglobinopathies vary widely in clin- gene, decreased transcription of the gene, abnormal ical severity. Most are relatively well understood. Gene RNA processing, or defects in the activity and transla- therapy for most of them would involve the same steps tion of the mature RNA (Treisman, Orkin, Maniatis, in replacing defective genes in bone marrow cells with 1983). their normal globin gene counterpart. Technical Note 5 • 59

Diagnosis of hemoglobinopathies able for moral, ethical, religious, or personal reasons; and, 4) genetic mutation is constantly reintroducing Because the symptoms of the hemoglobinopathies defective genes. are very heterogeneous, a definitive diagnosis usually Several alternative treatments are currently being requires assays for abnormal hemoglobin or DNA anal- developed experimentally that may be divided into ysis. The simplest and most common method of diag- three categories: 1) drug therapy, 2) gene therapy, and nosing sickle cell trait and anemia postnatally is 3) bone marrow transplant (Desnick, 1981). To date, through protein electrophoresis of a blood sample (see no form of gene therapy and only a handful of the diagram). Because of the risk associated with fetal drug therapies have progressed to the point of clini- blood sampling, however, this procedure may soon be cal trials, and bone marrow transplant appears to be displaced in prenatal diagnosis by the less risky pro- of possible use for only a small percentage of patients. cedure of DNA analysis of cells obtained through amniocentesis or chorionic villus biopsy (see app. A). DRUG THERAPY Electrophoresis can also be used to detect most Two types of drugs are currently being developed forms of thalassemia postnatally, except for the “silent to treat hemoglobinopathies. One type is designed carrier” form of alpha thalassemia which may now be “turn on” the synthesis of fetal hemoglobins to com- diagnosed using restriction endonuclease DNA analy- pensate for the faulty or insufficiently produced adult sis (Embury, et al., 1979). Prenatal detection of homo- hemoglobins. Some of these drugs are already being zygous beta thalassemia has been possible since 1974 tested clinically (Dover, 1983, 1984). The second type through quantitation of the amount of beta globin is meant to suppress the polymerization or gelling of manufactured by a fetal blood sample (Kan, 1977; the sickle hemoglobin molecule that distorts the red Alter, 1979). Prenatal diagnosis of certain forms of beta blood cells. Some of these drugs have also been tested thalassemia is also possible using DNA analysis (Alter, clinically (Bookchin, 1976; Dean, 1978; Lubin, 1975; 1981; Antonarakis, 1982; Boehm, 1983; Connor, 1983; Nigen, 1974). Estein, 1983; Hodgkinson, 1984; Orkin, 1982, 1983; Pirastu, 1983). GENE THERAPY Treatment of hemoglobinopathies through gene Treatment of Hemoglobinopathies therapy, or the insertion of normal globin genes into Currently, clinical treatment of hemoglobinopathies the embryo (germ line) or into bone marrow (somatic) is limited largely to treatment of infections, mitigation that is then implanted, is still entirely in the experi- of the associated symptoms (e.g., pain in the joints), mental stage in animals. The success rate of in vitro and organ-specific therapy (Dean and Schecter, 1978). germ-line transplants is still disappointingly low (see There is no effective long-term treatment for sickle app. B). The lack of animal models for hemoglobinopa- cell anemia, and the two treatments available for thies has effectively hindered both germ-line and thalassemia are only partially effective, with undesir- somatic-cell experiments. Recently, however, a model able side effects (Adamson, 1984). The first treatment for beta thalassemia was developed in the mouse involves repeated transfusions with normal red blood (Skew’, et al., 1983). Even given such models, however, cells can alleviate some of the symptoms, but even- the researcher is faced with the task of having the tually leads to toxic iron overload. The second treat- gene express at all, at adequate levels, at the right time, ment, bone marrow transplants, or the transfer of and in the right tissues in the whole animal. healthy bone marrow from a relative into the patient, BONE MARROW TRANSPLANT has been used successfully to treat homozygous beta thalassemia. This carries a high risk of failure, how- Gene transplant for hemoglobinopathies attempts to ever, and the possibility of an immune reaction of the take advantage of the relative accessibility of human patient against the transplanted marrow. bone marrow cells, where hemoglobin is produced. It could be argued that prenatal diagnosis obviates Bone marrow is removed from a donor who produces the need for postnatal treatment. However, there will normal hemoglobin, who has been matched for tissue always be children born with hemoglobinopathies and compatibility with the recipient patient who suffers other genetic diseases because: 1) parents often do not from a disorder of hemoglobin. The donor patient then realize that they. are carriers until they have had an receives radiation treatment sufficient to destroy the affected child; 2) parents who know they are carriers cells of his own bone marrow. Once accomplished, the may chose to take the risk of their child having a patient receives the transplants of the donor’s bone genetic disease; 3) prenatal diagnosis is often unaccept- marrow. The recipient is then treated with drugs to 60 Human Gene Therapy—Background Paper

suppress his or her immune reaction against the do- procedure is quite stressful to the patient, relatively nated cells (but this also affects general body defenses). risky, and not all patients can be matched with com- If not rejected by the host, the transplanted bone mar- patible donors. row begins to manufacture normal hemoglobin. The Appendixes

, Appendix A Diagnostic Technologies for Genetic Diseases

Diagnosing genetic diseases requires a partnership of and of themselves, as well as being partnered with two types of technologies: those for sampling bodily techniques for tissue sampling (see below). tissues and fluids, and those for analyzing such samples obtained before and after birth. Although ULTRASOUND fetal imaging is not tissue analysis in the strict sense, Ultrasound is commonly used in determining fetal it will he discussed here as a technology useful both age and defining large anatomic structures. It involves in conjunction with prenatal tissue sampling and by high-frequency sound waves, undetectable to the itself to view gross congenital malformations in utero. human ear, that are directed toward the uterus. A This section reviews the major imaging, sampling, and fetal image is created from the differential reflection analysis techniques, and comments on their current of the sound waves bouncing off diverse fetal tissues. and potential use as clinical tools. It applies only to Various gross congenital malformations may be de- prenatal and early postnatal diagnosis. tected using ultrasound, including hydrocephalus (ex- Often, the only ‘treatment” available for a fetus cess fluid of the brain), anencephaly (absence of all diagnosed as having genetic disease is the elective ter- or most of the cerebral hemispheres), absent or mination of pregnancy. All the stigma, emotion, and stunted limbs, and some defects of the heart and ethical controversy attached to this possible recourse kidney (Hobbins, Venus and Mahoney, 1981). For pur- can be-and has been—transferred to the diagnostic poses of tissue sampling, it is generally used in con- techniques themselves, and exacerbated by those tech- junction with amniocentesis (see below). There is cur- niques having been inapplicable until well into the 2nd rently little evidence of risk to the fetus from the small trimester of pregnancy. With the advent of techniques doses of ultrasound needed for in utero visualization. minimizing risk to the fetus and allowing diagnosis However, cautioning against routine screening, the within the first trimester, prenatal diagnosis may be- NIH Consensus Development Conference on Diagnos- come more accepted. tic Ultrasound Imaging in Pregnancy stated in its find- Controversy also attends the use of postnatal diag- ings, ‘(Lack of risk has been assumed because no nostic techniques. Genetic testing for certain disorders adverse effects have been demonstrated clearly in among high-risk populations—such as the screening humans. However, other evidence dictates that a hypo- for sickle cell trait among American blacks in the thetical risk must be presumed with ultrasound. Like- 1960s--have been said to stigmatize and demean in- wise, the efficacy of many uses of ultrasound in im- dividuals in those populations. Recent advances in proving the management and outcome of pregnancy diagnosing genetic disorders whose clinical symptoms also has been assumed rather than demonstrated, often do not surface until adulthood—such as Hun- especially its value as a routine screening proce- tington disease or familial hypercholesterolemia (a pre- dure . . . .Ultrasound examinations performed solely disposition for arterial hardening which causes early to satisfy the family’s desire to know the fetal sex, to heart attacks)-–have raised further questions: Would view the fetus, or to obtain a picture of the fetus a potential employer or insurance company have a should be discouraged. In addition, visualization of the right to this information? (see app. B). Propelled by fetus solely for educational or commercial demonstra- rapidly advancing rDNA technologies, the expanding tions without medical benefit to the patient should not use of these diagnostic techniques will soon necessi- be performed” (Office of Medical Application of Re- tate an answer to these ethical and political questions. search, 1984).

Fetal imaging FETOSCOPY Fetal imaging involves obtaining a visual image of the Fetoscopy entails the insertion of a thin fiberoptic fetus, either by means of special electronic techniques, scope through the abdomen into the uterus. The pro- or by using fiberoptic. Ultrasound and fetoscopy are cedure usually is done around the 18th week of gesta- the two major types of imaging. They can be used in tion. It permits a well-defined narrow-angle view of

63 64 Ž Human Gene Therapy—Background Paper

isolated parts of the fetus, and thus is used for fetal death (less than 0.5 percent), and is 99.4 percent ac- surgery as well as imaging. Fetoscopy, however, pri- curate (NICHD, 1976). marily is used to obtain fetal tissue samples (see Theoretically, amniocentesis could be performed below). early in the pregnancy since DNA analysis allows detection of the defect in any cell, regardless of tissue Technologies for fetal tissue sampling type or stage of fetal development. However, not enough fetal cells are available in the amniotic fluid The three major fetal tissue sampling technologies early on, and thus, amniocentesis is usually performed in use today are: fetoscopy, amniocentesis, and chori- no earlier than between the 16th and 19th weeks of onic villus biopsy. Fetoscopy is infrequently used be- pregnancy, Additionally, the cells from the fluid must cause it is relatively risky and difficult to perform. often be cultured for 1 to 5 weeks to yield a large Amniocentesis is relatively safe for both the fetus and enough tissue sample for analysis, further delaying mother, and is widely used today. Chorionic villus diagnosis. Thus, with amniocentesis the abortion of biopsy still is largely in the developmental stage in the an affected fetus, if elected, must be performed well United States, but has certain advantages that may into the second trimester when the results of the anal- lead to its widespread use in the near future. ysis become available. Such a delay increases the risk of complications associated with abortion including FETOSCOPY trauma, sepsis, and hemorrhaging (Brash, 1978). Abor- tion that late into a pregnancy also can carry a con- Direct tissue sampling via fetoscopy makes use of siderably increased risk of psychological and physical the fiberoptic scope—inserted into the uterus for fetal stress to the parents, and is generally less acceptable imaging purposes—to remove blood and skin samples, to parents and the community. The further develop- A needle or forceps, guided through the fetoscope by ment of methods to analyze uncultured amniotic fluid ultrasound, accomplishes this purpose, Various hemoglobinopathies, muscular dystrophy, and hemophilia cells continues to greatly speed diagnosis-e. g., a new technique for examining uncultured cells with an elec- can all be diagnosed using fetal blood samples (Hob- tron microscope can diagnose a glycogen storage dis- bins, Venus and Mahoney, 1981). However, with the ease 3 to 6 days after amniocentesis (Hug, et al., 1984). advent of sensitive DNA analysis techniques in the late One of the consequences of this increasing effective- 1970s, diagnosis of hemoglobinopathies such as sickle ness in neonatal and premature care is that the age cell disease and thalassemia can now be obtained at which viability is reached (see Technical Note 4) is through the less risky procedure of amniocentesis (see constantly being pushed back, mandating earlier pa- below). Fetoscopy, never widely practiced, carries a 3-to-6 percent risk of fetal death over and above the rental decisions vis a vis the course of the pregnancy. natural losses from spontaneous abortion and miscar- riage (Alter, et al., 1981; Rocker and Laurence, 1981), CHORIONIC VILLUS BIOPSY and is routinely performed at only a few medical Chorionic villus biopsy (CVB) is a relatively new tech- centers. nique for the sampling of fetal tissue that can be performed as early as the 8th to 10th weeks of pregnancy. AMNIOCENTESIS It entails taking a sample of the fronds of tissue, or Amniocentesis involves sampling fetal cells and other villi, that root the fetal placenta to the uterus. Ultra- substances present in the amniotic fluid. This is ac- sound is used to guide a catheter into the woman’s complished via a needle inserted through the abdomi- uterus to the villi, a tiny bit of which is then suctioned nal wall, through the wall of the uterus, and into the off using an attached syringe (see fig. A-l). The fetal fluid-filled space that surrounds the fetus. Amniocen- tissue is then separated from maternal tissue and sub- tesis normally is done using ultrasound to direct the jected to biochemical or chromosomal analyses that needle. take an average of one week to yield a diagnosis. In First used in the late 1960's amniocentesis is now contrast to amniocentesis, extensive culturing of the routinely employed with chromosome analysis tech- tissue is not necessary since a sufficient quantity of niques to detect abnormalities such as Down’s syn- DNA is obtained in the tissue sample. CVB can be per- drome, neural tube defects (through testing of the am- formed weeks, even months, earlier than either amniotic fluid), enzyme deficiencies (as in Fabry disease niocentesis or fetoscopy. and Lesch-Nyhan syndrome), and hemoglobinopathies CVB was first used in China (Department of Ob- (through testing of cultured fetal cells). Amniocentesis stetrics and Gynecology, Anshan, 1975), the U.S.S.R. is widely available, has a low associated risk of fetal (Kazy, Rozovsky and Bakarev, 1982), and Norway. It App. A—Diagnostic Technologies for Genetic Diseases 65

Figure A-1.—Chorionic Villus Biopsy much of the discrepancy may be due to the time when the procedures are performed. There is a higher spontaneous abortion rate in the first trimester, when CVBs are done, than in the second trimester, when amniocentesis is done. Some even predict that CVB will replace amniocentesis within a few years (Product News, 1984). Current clinical applications of chorionic villus biopsy include at least three groups in England, with four or five more testing it for clinical use in that country (Dr. Robert Williamson, Ph. D., personal communication, 2-16-84). Other countries include Italy (over 200 cases of Down’s syndrome have been diagnosed by a Milan group) and France (to diagnose hemoglobinopathies; Dr. Robert Williamson, Ph. D., personal SOURCE: Product News, “Chorionic Villus Biopsy,” Out/ook, January 19S4, p. 8. communication, 2-16-84). Carolyn Brooks, artist, has been considered ethically acceptable in England and used since mid-1981 for prenatal diagnosis of cer- Tissue and fluid analysis tain “high-risk” disorders such as hemoglobinopathies (Old, et al., 1982), and fetal sexing of pregnancies at Genetic diseases were first detected through their risk of sex-linked diseases (Gosden, et al., 1982), mainly characteristic behavioral or physical traits. This ap- Duchenne muscular dystrophy. It is used less often proach, combined with family histories, still is impor- there to diagnose the more common Down’s syn- tant to the diagnosis of many genetic diseases, espe- drome. Unlike amniocentesis, however, CVB cannot cially those for which the underlying biochemical and be used to detect noncellular substances in the amni- genetic defects are not known. However, behavioral otic fluid, like alpha fetoprotein, whose presence in- and physical examination is generally not applicable dicates a high risk of neural tube defects. to prenatal diagnosis, or on the cutting edge of diag- According to the World Health Organization’s nostic technologies, and will not be discussed here. registry, CVBs have been performed in the United Many genetic diseases have surfaced in recent years States since mid-1983. By November of that year, a whose physical and behavioral manifestations are not projected 12 percent associated fetal loss rate was readily apparent, are progressive, or take several years reported after only 240 CVBs had been performed in to emerge. Many such diseases are detectable through the U.S. and Europe (Ward, as cited in Jackson news- biochemical assays for characteristic imbalances or ab- letter, 1983). Because of this, several researchers (Lipp- normalities of certain body substances. man, 1984; Hecht, Hecht, Bixenman, 1984) contend A small but growing number of diseases may now CVBs are risky and should be used with caution. Cur- be diagnosed through direct analysis of the genetic ma- rent clinical data from approximately 2900 CVBs per- terial. This was once only possible for gross chromo- formed to date in these same countries seems to in- somal abnormalities involving the absence or duplica- dicate that the observed fetal loss is 4.2 percent tion of entire chromosomes, but recent advances in (Jackson, 1984 newsletter). This, however, includes an molecular genetic technology have made possible de- unquantified number of spontaneous abortions and tection of minute defects within the chromosomes. miscarriages that are a danger to any normal preg- Such genetic analysis can allow diagnosis of the dis- nancy. In four similar series of ultrasound observa- ease before the biochemical defect is detectable, espe- tions on ultrasound pregnancies and control groups, cially prenatally, and before it becomes clinically the observed fetal loss rate is in the neighborhood of apparent, making possible early treatment and some- 2 percent. Extrapolating from that, it may be reason- times even prevention. able to assume that the risk of fetal loss that might be associated with CVB is 2 to 3 percent. Any fetal loss BIOCHEMICAL ASSAYS rate, however, is highly dependent on the expertise Many genetic diseases are manifested as biochemical of the laboratory involved, and there are laboratories imbalances caused by the reduced or absent activity with a reported O percent observed fetal loss (Jackson, of certain enzymes that help manufacture a given 1984 newsletter). Although generally higher than the chemical, or convert it into another useful product. 0.5 percent loss rate associated with amniocentesis, Such enzyme deficiencies underlie a spectrum of dis- 66 Ž Human Gene Therapy—Background Paper

orders ranging from albinism to hemolytic anemia to DIRECT ANALYSIS OF DNA some immunodeficiency diseases. X-ray, urine analy- Cytogenetics: Visualization of Chromosomes.— sis (for excretion of abnormal amounts of certain ac- Cytogenetics is the examination of chromosomes cumulating precursors) and physical or mental exam- under a microscope in order to detect gross changes inations are often used for preliminary detection. in chromosomal structure. One of the first clinical ap- However, enzyme assays of the blood or other tissues plications of this technique was the detection of Down are generally necessary to make a definitive diagno- syndrome (Lejeune, 1959), in which the cell carries an sis of such diseases. Tay-Sachs disease (TSD), for ex- entire extra chromosome 21. Although many reports ample, is a metabolic disorder primarily affecting Jews on other numerical chromosomal aberrations fol- of Eastern European descent (1:3,000 US.) (Stanbury, lowed, researchers were often unable to identify et al., 1983) caused by the lack of an enzyme, Hex- which chromosome was involved. Characterization of oseaminidase A, that results in the accumulation of banding patterns on particular chromosomes in the lipids in the brain. TSD is characterized by progressive late 1960s and early 1970s allowed the identification neurological degeneration including dementia, paraly- of specific chromosome pairs as well as parts of each sis and blindness. Diagnosis routinely involves enzyme chromosome (Hirschhorn, 1981). An array of chromo- assays of cultured amniotic fluid cells prenatally and somal deletions, duplications and translocations, and of the blood serum postnatally. the corresponding syndromes, have since been iden- Lack of activity of an enzyme or other substance is tified (Borgoankar, 1980). Down syndrome and other sometimes due not to a quantitative lack of the sub- major numerical and structural chromosomal defects stance, but to a structural defect that prevents it from afflict about 1 in 160 live-born infants (Hook and functioning properly. Electrophoresis is a method of Hamerton, 1977). Such chromosomal defects—includ- distinguishing such variants through the different ing abnormalities of the sex chromosomes such as speeds at which they migrate in an electrical field Klinefelter syndrome in which the male possesses an according to their total net charge—a characteristic extra X chromosome, causing sterility and feminiza- that may vary with molecular structure. For example, tion—are now routinely diagnosed both before and electrophoresis can reveal the absence of any one of after birth using cytogenetics. the three major classes of immunoglobulins—as well Genetic Markers.--The rapid progress in recom- as variations within any one class—that characterize binant DNA techniques since the mid-1970s has made certain immune deficiency diseases. It also can detect possible detailed analysis of particular genes on the and distinguish between both heterozygotes (i.e., sickle chromosomes, and the characterization of minute cell trait) and homozygotes (i.e., sickle cell disease) for genetic defects that are not detectable through exam- the sickle cell gene (see fig. A-2). Protein electro- ination of gross chromosomal structure. In recent phoresis is a relatively inexpensive and expedient tech- years, the defective genes underlying various other nique, and is commonly used for postnatal detection heritable diseases have been identified—including of hemoglobinopathies. Because of the relatively high Lesch-Nyhan syndrome (Jolly, et al., 1982, Brennand, risk involved in obtaining fetal blood samples (see et al., 1982) familial hypercholesterolemia (Bishop, Technologies for Fetal Tissue Sampling, this appendix), 1983), and phenylketonuria (Woo, et al., 1983). Within electrophoresis is less commonly used for prenatal the past 2 years, genetic “markers” (though not the diagnosis. There are some cases in which electro- actual genetic defect) have been discovered for two phoresis is insufficient to distinguish particular geno- important genetic disorders: Duchenne muscular dys- types, and therefore is frequently combined with a trophy (Murray, et al., 1982) and Huntington disease volubility test. In most cases, these two tests will suf- (Gusella, et al., 1983). fice to identify a hemoglobin disorder. The discovery of identifiable markers for genetic defects opens up the possibility of using them to aid Figure A-2 in diagnosis. Such markers might be useful as prenatal tests, for postnatal identification of risk, or perhaps + even for genetic screening. For example, phenylketonuria (PKU), an inherited enzyme deficiency that, if untreated, can cause severe mental retardation, could not be detected before birth until recently (although biochemical tests were available for postnatal screening). The recent discovery of a genetic “probe)” or

SOURCE: Bowman, J. E. and Goldwasser, E. (1975) Sickle Cell Fundamentals, The Unlverslty of Chicago. App. A—Diagnostic Technologies for Genetic Diseases Ž 67 short stretch of DNA specific to the defective gene, abnormal gene by identifying differences in a piece has made possible not only prenatal detection, but also of DNA close to the gene causing the disease. This tech- carrier identification (Woo, et al., 1983). This means nique depends on using restriction enzymes indirectly, that parents at risk of having a child affected by PKU rather than directly, and is correspondingly less can be identified. This opens up the technological pros- precise. pect of parental carrier screening to supplement or People show characteristic variations in how their replace routine newborn screening. DNA is cut by certain restriction enzymes, just as they Direct analysis of DNA is being used now in the diag- have specific blood groups. These variations usually nosis of several other diseases as well, including some are not significant in and of themselves. The place disorders of hemoglobin and one form of dwarfism along the DNA that is responsible for the variations (Antonarakis, et al., 1982). Direct binding of DNA can be located. The utility of such variations comes probes to patient DNA could theoretically be devel- when, by chance, a particular pattern is caused by dif- oped for any disease caused by a single gene. ferences close to a disease-causing gene. When this Genetic markers can be of several types. Some de- occurs, it is often possible to track the abnormal gene pend on the presence or absence of specific bio- by following the restriction fragment pattern. This chemical activities. Others depend on the differences technique of establishing “guilt by association” is called in how DNA is cut by enzymes specific to certain linkage analysis (denoting a physical genetic linking nucleotide sequences in combination with DNA between a trait of interest and an identifiable marker) probes—specific detectable stretches of DNA con- and has permitted tracing of the Huntington disease structed in the laboratory that bind directly to either gene, (Gusella, et al., 1983) the Duchenne muscular the gene causing the disease or a piece of DNA so close dystrophy gene, and genes underlying several hemo- to the disease-causing gene that it can be used as an globin disorders (Boehm, et al., 1983). Because the indicator for the defective gene. The techniques are technique does not require any special knowledge briefly described below. about which gene causes a disease, or the biochemical Restriction Enzymes. -Restriction enzymes are lesion responsible, restriction fragment analysis may proteins that are found in bacteria that cut DNA at be used to diagnose diseases whose molecular mech- specific sequences. Human DNA is composed of roughly anisms are not yet known, such as cystic fibrosis. A 3 billion pairs of nucleotides (see Technical Note 1); major disadvantage of the technique is that the restric- restriction enzymes look for stretches of 4 to 12 nucle- tion enzyme pattern usually varies from family to otides that are arranged in a particular order, and cut family, and many members of each family must be the DNA at a site either in the middle of the sequence tested before genetic detection within any one family or near to it. When the DNA from human cells is so is practical. treated, DNA fragments of many lengths are gener- The technique is analogous to searching for passen- ated. The DATA from any one individual will have a gers of a downed plane. In thousands of miles of specific pattern because-the sequence recognized by mountainous territory, the wreckage of an aircraft is a particular enzyme will occur in characteristic places found by tracing its radio distress signal. This does in that person’s DNA. not give much information about the condition of the People generally have very similar patterns of DNA crew or the circumstances of the crash, but it does fragmentation when their DNA is treated with restric- permit restriction of the search to a smaller area, and tion enzymes, and so most enzymes have not yet been increases the probability of finding the passengers. shown to be useful for diagnosis. Some enzymes, how- The crash site itself may provide some clues about the ever, generate differences that correlate with disease. cause of the mishap and where to look for survivors. The DNA coding for sickle cell disease, for example, In this analogy, the radio signal is like a linked genetic is cut by an enzyme that does not cut the normal gene. marker, while the defective gene is like the crash site. Therefore, when this enzyme is used on DNA from DNA Probes.--Gene probes are short stretches of a patient, the one DNA fragment found in normal in- DNA that bind to a specific DNA sequence. Through dividuals is cut into two smaller pieces. These pieces cloning, many identical copies of a probe can be made. can be seen using standard laboratory methods, and Probes are usually made out of DNA that has been the technique has been used to detect both sickle cell specially labelled with either a radioactive or chemi- disease and sickle cell trait (Orkin, et al., 1982). cal tag that allows the probe to be used to detect spe- In most cases, the differences between the normal cific DNA sequences, employing. standard laboratory and the abnormal gene will not be so easily identified: met hods. the disease-causing mutation will not occur where re- Probes are often used in combination with restric- striction enzymes are known to cut. In this case, one tion enzymes. First the DNA is chopped into manage- can sometimes identify people who might carry the able sizes by restriction enzymes, and then a probe 68 . Human Gene Therapy—Background Paper is bound to the DNA. In the instance of the sickle cell cell disease (Wallace, et al., 1981; Orkin, 1982; Con- gene mentioned above, for example, the probe corre- ner, et al., 1983), and some thalassemias. (Orkin, et al., sponds and binds to an abnormal variation of the he- 1983; Pirastu, et al., 1983) An oligonucleotide probe moglobin gene that causes the disease, allowing its has also been developed for another genetic disease, detection. alpha-1-antitrypsin deficiency (an inherited deficiency Probes come in different sizes. Most sequences used of a blood protein that can lead to lung and liver dis- as probes are fairly long, composed of many copies ease), making prenatal diagnosis possible (Kidd, et al., of a single ordered sequence of hundreds or thousands 1984). of nucleotides. These are usually made using bacterial The power of the new diagnostic techniques can be clones of a gene or DNA fragment. Some short probes, imagined by noting that they can detect differences called oligonucleotide probes (“oligo-” means few), can of a single letter in a book composed of three billion be chemically manufactured in the laboratory. These letters. If each gene is a paragraph, then only a few small highly specific probes can, under carefully con- paragraphs in a long monograph have been investi- trolled conditions, detect the difference between genes gated using the new techniques; more of the text will that differ only in a single nucleotide in their se- be tested over the next few decades, and the mean- quences. This property has been used to detect sickle ing of the book may thus slowly become clearer. Appendix B Privacy and Control of Genetic Patient Data introduction Genetic patient data are different from other types of disease- related medical information, in the follow- Some of the same recombinant DNA technology that ing ways: makes human gene therapy possible will also facili- In contrast to communicable diseases, the public tate the identification of many more individuals with at large is not at risk of contracting genetic dis- genetic diseases than earlier techniques allowed. This ease, since it can be transmitted only to progeny. new technology should result in a dramatic increase Because of the genetic transmission of the disease, in the amount of genetic patient data that can be col- information about close relatives may reveal in- lected, much of which has never been available before. ] formation about oneself, and vice versa. Closely However, the ability to gather potentially large related individuals can benefit from this infor- amounts of new genetic data about individuals raises mation. questions about rights of privacy regarding that in- Because some genetic diseases, such as Hunting- formation, as well as the ability of others to have ac- ton disease, colonic polyposis, or polycystic kidney cess to it. disease, may not be expressed until middle or old age, genetic information in some cases provides WHAT ARE GENETIC PATIENT DATA? a look into the future health of an individual. Genetic patient data refer to information collected Because of the emotional concern of the patient about an individual relating to his or her genetic con- when learning about a genetic disease in their stitution. Information of this sort can include a large family against which he/she has no defense. number of individual traits, ranging from eye color Future generations may inherit the disease, and or blood type to predispositions to or presence of vari- therefore have an interest in it. ous diseases. Since genes determine many personal Those potentially interested in genetic patient data characteristics, genetic data may reveal important include the patient, his or her family, insurance com- facts about an individual’s physical and intellectual panies, employers, health care providers, and the Fed- status or potential. One’s genetic complement is an in- eral Government. voluntar y endowment, since the genes are passed on from parents, and genetic characteristics are not gen- HOW ARE GENETIC PATIENT DATA COLLECTED? erally subject to change. Genetic patient data are collected about individuals Policies on access to genetic patient data must bal- in many ways, but the bulk of specific information on ance the benefits deriving from disclosure against the genetic traits derives from two main sources: family need to preserve individual privacy. The benefits to histories and genetic tests.2 public health and other priorities often determine that A family history can be relatively easy to collect, and medical information be disclosed. Examples of situa- most genetic patient data available to physicians are tions in which medical information is used for public of this type. A family history is usually obtained by good or prevention of harm include reporting child asking the patient questions about the presence of dis- abuse or other criminal conduct, notifying State offi- eases in his or her family that are known to be in- cials about the presence of communicable disease that herited. Histories can often be supplemented by in- might endanger public health, and use of disease sta- quiry among other family members. The importance tistics in planning priorities for biomedical research. of genetic factors varies between diseases. Recent data Patients might be harmed, however, as a consequence on Alzheimer disease indicate that a significant frac- of disclosing their genetic data. They might be socially tion, at least one-third of cases may be genetic (Breit- stigmatized, have difficulty finding a mate, encounter ner, 1984; Folstein, 1981; McKusick, 1983), while other barriers to obtaining life and health insurance, or be diseases, such as PKU, are always due to genetic de- discriminated against when seeking employment. fects. Variation in the genetic component among different diseases and even among diseases of the same IThe number of cloned human genes is an index of this increase in poten. tial genetic patient data The number of cloned human genes reported at the Gene Mapping Meetings has risen from 22 in 1982 to 132 in 1984 (Skolnick, These include a varlet> of biochemical and genetic tests See app A for et al., 1984) further information on genetic testing techniques.

69 70 Ž Human Gene Therapy—Background Paper

type can be due to several factors, discussed in the when the mother is 35 years or older, if a previous overview, such as: child were born with a genetic defect, or if both incomplete penetrance, parents are known carriers of a gene which can be variable expression, detected by such screening (Milunsky, 1980), Screen- environmental factors, ing at birth can identify newborns who require special different patterns of inheritance: dominant, care, such as PKU newborns who need a special diet, recessive, or sex-linked, low in phenylalanine. For this reason, newborn screen- multigene traits, and ing for PKU is required by most States. multifactorial traits. Genetic screening raises many medical, ethical, legal, As a result of these factors, genetic patient data col- and economic questions, such as: 1) Can family mem- lected from family histories can alert individuals to bers crucial for testing be legally coerced to partici- personal health risks and statistical likelihoods, but it pate in linkage studies (see ch. 1), 2) Should a person generally cannot predict with certainty whether an of any age have the right to be tested and informed individual with a family history of cardiovascular dis- of test results?, 3) Should spouses or parents be per- ease or cancer, for example, will actually develop those mitted to know this information?, 4) Does a child have disorders. the right to genetic information held by his parents?, With reliable genetic tests, it is sometimes possible 5) Should physicians inform at-risk individuals of the to determine the presence of genes that can cause dis- availability of testing?, and 6) Can the release of in- ease, permitting more accurate determination of the formation from genetic testing be withheld in employ- probability of expressing symptoms. Genetic testing ment and health insurance questionnaires? (Kurlan, may be performed as a result of information obtained 1983). One of the most difficult issues is the use of in the family history, or can, in some cases, be initi- abortion to prevent genetic disease. Other questions ated to screen for diseases common in a more gener- include whether the benefits of genetic screening ex- al population to which the patient belongs. ceed the costs of the procedure, and if so, whether Genetic patient data are collected in several different newborn screening should be made mandatory (Presi- contexts. Family histories are recorded when an indi- dent’s Commission, 1983). The President’s Commission vidual first visits a physician, and generally when a for the Study of Ethical Problems in Medicine and Bio- person buys individual life insurance. Genetic testing medical and Behavioral Research enunciated five prin- is often performed in the context of making personal, ciples for genetic screening with the following recom- medical, or reproductive decisions, and such tests are mendations: performed at different times for different reasons 1. Confidentiality. “Genetic information should not (Rowley, 1984). Carrier screening can identify in- be given to unrelated third parties . . . ;“ dividuals who carry one copy of a deleterious gene 2. Autonomy. “Mandatory genetic screening pro- so that they may be made aware of the risks of hav- grams are only justified when voluntary testing proves ing a child with a genetic disease and make a clearly inadequate to prevent serious harm to the defenseless, informed decision about having children. Carrier such as children, that could be avoided were screen- screening has been performed on groups at high risk ing performed;” of carrying certain genes, such as Blacks and Medi- 3. Knowledge. “Decisions regarding the release of terranean populations, who may have hemoglobin dis- incidental findings (e.g., nonpaternity) or sensitive find- orders, or Eastern European Jews who may carry Tay- ings (e.g., diagnosis of an XY female) should begin with Sachs disease.3 the presumption in favor of disclosure . . . ;“ Prenatal screening is performed to identify possible 4. Well-being. “Screening programs should not be genetic defects in the fetus and allow parents to decide undertaken until the test has first demonstrated its whether it should be brought to term or if it might value in well-conducted, large-scale pilot studies . . . .A require special care when born (see app. A). Prenatal full range of prescreening and followup services for screening is indicated in several situations, including the population to be screened should be available before a program is introduced;” and

Screening for most genetic disorders is performed on a \ olun[arj, basis, 5. Equity. “Access to screening may take account although most States require screening of newborns for PKLI and some other of the incidence of genetic disease in various racial or disorders Fi\e States require such testing under all circumstances, 3(I per. ethnic groups within the population without violating mit denial on the basis of religious convictions, and Y others permit some other bases for refusal, PK[ I screening not required in three States (Aodrews, the principles of equity, justice, and fairness. ” IY&-ld) Some other mandatory screening laws, particularly those that im ol~e This paper will not discuss further the issues related srreenmg of adults for potential rarrier st~tus, hale been repealed beriiuse of rl~iln]s made b! the affected groups that tht>y were being s]ngled out and to the collection of genetic patient data; rather, it will d!srrlminated against (Rowley, 1984) address issues which arise after the data is collected. App. B—Privacy and Control of Genetic Patient Data . 71

WHY ARE GENETIC PATIENT DATA IMPORTANT? nity and the identification of criminals in court cases. In addition, it would be impossible to conduct research Genetic patient data can play an important role in on genetic diseases. The benefits, however, must be the life of an individual, affecting such diverse areas as: weighed against the fact that unrestricted access to choice of spouse; genetic patient data would violate the autonomy of in- psychological health dividuals to reveal only the personal information of reproductive decisions, such as their choice. Two models illustrate the ways in which -decisions to have children health records are treated: the physician-patient model -decisions to undergo prenatal screening, and and the public health model. -decisions to terminate pregnancy; decisions about personal health risks affected by diet, smoking, and health habits; THE PHYSICIAN-PATIENT MODEL decisions about the personal health risks con- The precedent for confidentiality in the physician- nected with certain jobs; and patient relationship was set many years before the decisions concerning financial, insurance, and Hippocratic oath was written (Walters, 1983), and retirement plans. since that time, physicians have held to an ethical code These are among the most personal decisions that of privacy in matters relating to patient’s records. an individual makes, and it is therefore important that Utilitarian Justifications.--One way to consider their privacy be ensured. However, as mentioned the privacy of the physician-patient relationship is above, there are others besides the individual who utilitarian: for the physician to effectively treat the in- have an interest in genetic patient data, and their individual there must be trust between them. A patient terests must also be considered. can only be expected to reveal delicate health issues Genetic patient data may also be significant because to the physician if the information is to be held in strict they have the potential for being misunderstood or confidence. In daily life, a person can control whether misinterpreted by the public. Earlier genetic screen- or not to disclose personal information to others. One’s ing programs to identify carriers of sickle cell disease private thoughts may be represented by a set of con- caused some individuals to be stigmatized because centric circles, with the outermost circles containing they and others did not understand the difference be- information that a person is willing to give to anyone, tween the carrier state and the disease state. Some such as height or occupation, and the innermost circles of these individuals were mistakenly treated as ‘sickly’ containing personal information that is reserved only children or discriminated against in employment or for those closest to him or her, if anyone. In the med- insurance coverage (Rowley, 1984; President’s Com- ical model, a patient allows a physician to enter an mission, 1983). This and other examples highlight the inner circle in order to get help with a medical prob- need for greater understanding of genetic conditions lem, and the physician therefore owes a duty to the before using genetic patient data to direct social pol- patient to keep the information confidential (Walters, icy. As more is discovered about the genetic basis of 1983). Certain types of genetic patient data may be certain diseases, such as alcoholism, schizophrenia, or considered so proprietary that, “Doctors in whose complex traits such as intelligence, issues of individ- records this information may reside should hold it ex- ual privacy relating to genetic patient data may be- tremely confidential and should not keep it in the per- come even more important than they are today. son’s general medical file” (Wexler, 1983). Patient Rights.-–Another approach to the Privacy and access physician-patient relationship is centered on the rights of the individual. These rights become particularly im- In any discussion of the privacy of health records portant in considering the difference between collec- it is important to consider the tradeoffs between an ting a family history and performing genetic tests. A individual’s right to privacy and others’ interests in patient has direct control over whether to provide a having access to the same information. Privacy and family history to a physician, while genetic testing can access are two sides of the same coin, and to preserve be performed on blood, body fluids, or tissues. This an individual’s right to privacy is to deny others that technical ability to collect genetic patient data raises access. If all genetic patient data were made complete- two main concerns. First, the patient does not exer- ly private, society would forego the potential benefits cise the same discretionary control over information accruing from availability of that information, such garnered from biochemical testing as he or she does as planning national biomedical research priorities and in relating a family history: the patient merely assents preventing potential harm to relatives, Equally unavail- or dissents to undergoing the test. Second, blood or able would be data vital to the determination of pater- tissue samples collected at other times for other rea- 72 . Human Gene Therapy—Background Paper

sons may be tested genetically, without the knowledge decide whether their belief justifies reporting the pa- of the patient. tient to the police (Walters, 1983). Even following the guidelines for informed consent, Since there are many different issues involved in the with the patient agreeing to genetic tests, their tech- disclosure of information, it is instructive to look at nical nature increases the risk that the patient does several different cases of the disclosure of information, not fully understand the possible significance of the beginning with the disclosure to the patient, himself. data. Patients may also fail to anticipate the potential harm disclosure might cause him or her. The consent DISCLOSURE TO THE PATIENT of the patient is required to remove blood or tissue The doctrine of informed consent, so called, was ini- body, and also to perform tests, but from his or her tially developed to assure a patient’s self-determination it is important that the patient be informed of all the and right to decide whether to undergo health care tests which are done and that a concern for the pri- procedures. One of the most important arguments for vacy of the patient extends to the control of tissues an informed patient is that only with adequate infor- removed from his or her body. mation can an individual make informed decisions con- Under normal circumstances, health records are not cerning his or her health or lifestyle, and genetic released to third parties, except with the consent of information can play an important role in these deci- the patient, so that medical information which exists sions. Another, recently discovered, and perhaps more in the record is still under the control of the patient. compelling argument is that informed consent may ac- Nevertheless, current practices involving information tually provide numerous physical and psychological release allow little or no control over withholding parts benefits to the patient (Andrews, 1984a). of data. A patient with a genetic trait or disease is Studies of elective surgery patients have provided rarely able to release only the parts of his or her rec- the most notable evidence of the beneficial effects of ord that do not contain that information once a waiver information disclosure. Patients ‘briefed’ on the nature is signed, as those waivers are considered as ‘blanket’ of surgical procedures and postoperative sensations consent for release of their entire medical record. exhibited a greater capacity to adjust to postoperative However, even in instances when the physician-patient stress, needed less pain medication, and had fewer relationship can be maintained, there are several cases recovery days in the hospital. In another study of hos- which supersede it and these can be grouped and pital patients, one of the chief reasons for refusing called the public health model treatment seemed to be the occurrence of unexpected procedures which exacerbated patient uncertainty THE PUBLIC HEALTH MODEL and aroused patient anger (Appelbaum, 1982). A physician’s duty to protect the privacy of his pa- However, the therapeutic effects of information dis- tient may be superseded by his duty to prevent harm closure are not limited to surgery patients. Patients to others, such as the patient family or society in gen- scheduled for endoscopic examination— where a fiber- eral. For example, a physician must report the occur- optic tube for internal viewing is placed down the rence of cases involving gunshot wounds, battered esophagus and into the stomach—heard a taped children, and certain communicable diseases (Green description of the sensations frequently experienced and Capron, 1974; Walters, 1983). Government inter- during the procedure and subsequently needed less est in reporting communicable diseases centers on medication to tolerate the examination than those who identifying both the disease and those individuals who did not hear the tape. Similar results indicating the are at risk of contracting it, and mobilizing efforts to benefits of disclosure have been found in studies in- prevent or treat it. With certain communicable dis- volving blood donors, burn treatment, and sigmoid- eases, such as gonorrhea, there is a high risk of dan- oscopy examinations (Andrews, 1984a). ger to significant numbers of people, and government Disclosure also acts as an informal check and bal- involvement may be a way to reduce the risk. With ance system whereby a patient may reject a procedure gunshot wounds, it is possible that the injury occurred that is being advocated more for the benefit of the as a result of an illegal act that may place others at practitioner than the patient. Although generally act- danger, and so government action may prevent harm ing in the patient’s best interest when they propose to others. This concern for the public well-being often diagnostic procedures and therapies, physicians may places the physician in a difficult ethical position, hav- be motivated by strong financial and professional con- ing to choose between the privacy interests of his pa- siderations that place them in a conflict of interest tient and the interests of society. This is especially true (Schneyer, 1976). in the case of psychiatrists who may have reason to Another potential benefit of informed consent is that believe a patient may become violent, and they must it may enhance the quality of physicians’ decisions. By App. B—Privacy and Control of Genetic Patient Data . 73

requiring physicians to provide clear and factual in- are followed when disclosing information to third formation about the risks and alternatives to a given parties: procedure or therapy, they may recognize and ac- there should be a high probability of harm to count for their own judgment biases and suggest a others, more thoroughly considered course of action. Addi- the potential for harm should be deemed serious, tionally, in the course of the physician describing a such as being irreversible or fatal, and procedure, the patient may reveal information perti- there should be reason to believe that the infor- nent to the treatment choice— information which may mation will prevent harm. (President’s Commis- result in a different choice of action. sion, 1983, p. 44). There is no consistent or prescribed amount of in- Reasonable attempts for voluntary consent should formation due the patient on a national basis, but there be made, since it would not be ethical and may not are three measures by which the legal system gener- be legal4 to disclose information without the consent ally determines the patient’s right to decide. One is of the patient, and only the relevant information the Reasonable Physician Standard, whereby the phy- should be disclosed. These guidelines will be consid- sician follows the standards of the community to de- ered in the following situations: disclosure to family termine how much, or whether to disclose anything members, insurance companies, employers, and the to the patient. The second is the Reasonable Patient government. Standard, whereby the patient is informed of any and all information necessary or helpful to a reasonable DISCLOSURE TO FAMILY MEMBERS patient. The third is the Individual Patient Standard, There are many situations in which genetic data whereby the physician must take into account what about an individual may affect decisions made by close he/she knows about the individual patient to deter- relatives. Genetic data may be of greatest importance mine what should be disclosed. Each of these stand- to one’s spouse or prospective spouse because it may ards carries different weight with different courts, and directly affect the couple’s reproductive decisions. The despite the widespread acceptance of the doctrine and reason for disclosure is to prevent direct harm to the its continued expansion, the patient’s right to informed unborn and indirect harm to one’s spouse. In many consent has always been and continues to be a qual- cases, one partner would wish to inform the other ified one (Andrews, 1984a). about possible genetic risks so that together they may Courts almost unanimously note several exceptions make an informed decision about having children. In to the general rule: an emergency situation where the other situations, the affected partner may prefer not patient is unconscious or otherwise unable to author- to inform the other, in order to avoid being identified ize treatment, and serious damage will occur if treat- as the cause of having deformed children or being the ment is not undertaken; where the patient is deemed reason for not having children at all. incompetent to make a decision; where a waiver to Disclosure to a spouse may indeed prevent harm if informed consent is signed by the patient; and where the couple decides not to have children at high risk therapeutic privilege is invoked because disclosure of genetic disease. The reasons supporting disclosure poses such a threat of psychological damage as to be of genetic patient data to a spouse increase with both unwise from a medical viewpoint (Andrews, 1984a). the severity of a potential genetic disease and the probability of the children inheriting it. Third party access Another reason for disclosure goes beyond reproductive decisions to include the need for the spouse Several groups besides the individual would have an and family to know the genetic condition of the af- interest in genetic information gathered about an infected person in order to make plans to care for them, dividual. For example, family members may wish to both physically and financially. For example, if it were be alerted to potential health risks revealed by the known that the provider of a household would develop genetic data about a close relative Also, insurance com- polycystic kidney disease or Huntington disease, the panies, employers, and the Federal Government have family would have to plan for the debilitating effects an interest in access to genetic patient data for various of the disease, significant medical expenses, and future reasons which will be described below. In each case, loss of income. there is conflict between third party access to information and the individual’s right to privacy.

A physician’s duty to protect the confidentiality of ‘,A phjsician who discloses meciical data to relatiles or third parties ma} the patient data can be upheld if certain guidelines he sued for damages resulting from \iolation of the patient’s prnacj;

38-803 0 - 84 - 6 , QL 3 74 • Human Gene Therapy—Background Paper

Since children receive half their genes from each of 30 to 120 days (Health Insurance Association of parent, they also have an interest in the genetic data America, 1984). The access of insurance companies to of their parents. The case for disclosure to children genetic patient data, therefore, does not seem to be is strong because there may be a significant probabil- an issue for most group health insurance coverage . ity of harm that could be reduced if the children were Individual health insurance policies, however, are to take health precautions. In families with colonic similar to life insurance policies, since they both use polyposis, for example, those with the disease are at medical information to determine the premiums. high risk of developing colon cancer, and preventive Group health insurance policies, generally used in removal of the colon can thwart almost certain death employee benefit packages, usually require applicants from cancer. Knowledge about colonic polyposis can, to sign a blanket waiver permitting access to their en- therefore, be of extreme importance to those at risk. tire health record, including family history and any Genetic patient data may also be relevant to health genetic patient data. care of other relatives. In families that carry the gene The people who purchase individual policies include for retinoblastoma, for example, children are at high those over the age of 65, the self-employed, and work- risk of developing potentially fatal eye cancer. Knowl- ers in small businesses. The unemployed do not qual- edge that a relative has the disease may precipitate ify for group insurance and usually cannot afford in- more careful scrutiny of cousins and siblings who are dividual policies. For the remainder of this paper, the also at risk, thus potentially saving lives. term “insurance” will encompass both life and indi- The case for access to more distant relatives is gen- vidual health insurance. erally not as strong as for the immediate family, since Life Insurance Companies.—Most life insurance the predictive value is lower, but here, too, genetic companies require an applicant to answer several patient data might alert the person to potential health questions about his or her health on an application risks. If the severity of the disease and the degree of form, and then if the answers warrant, and if the cov- risk is high and action can be taken to prevent harm, erage sought exceeds a certain amount, they may re- then disclosure to more distant relatives maybe justified, quire the applicant to release his or her medical Finally, genetic patient data can be of use to children records, submit to a medical examination, or both. The and other relatives of parents affected with a genetic results of these medical findings and other data are disease when considering reproductive decisions. then used to determine the life insurance premiums Prospective parents may choose not to bear children for an individual, or whether the person is insurable or may take special steps to monitor their children as at all. Some of the questions are related to conditions a consequence of information obtained about diseases with a genetic component, such as sickle cell disease, that are more likely in their children than in the gen- and if an applicant reports or displays the symptoms eral population. it is unlikely that he or she will be insured. Likewise, an applicant may be asked about the presence of heart disease, high blood pressure, or stroke in his or her DISCLOSURE TO INSURANCE COMPANIES immediate family, and an affirmative answer would The insurance industry is the second largest user increase the risk factors involved, even though the of medical information in the United States, after the genetic basis of these diseases is not clear. The use Federal Government (Baskin, 1978). Both life and of this genetic patient data raises several ethical ques- health insurance companies use medical information tions that are not new, but the potential increase in in order to assess the probability of health events for the amount of genetic patient data in the future may those who are insured. There is a great deal of varia- increase the significance of these issues. tion between individual firms in the amount of infor- Risk Classification. -Insurance companies gener- mation required to accept an applicant. ally use several factors to determine an individual’s Health Insurance Companies.—One hundred insurance premium, such as gender, occupation, ninety million people in this country had some form weight, and blood pressure (Cummins, et al., 1983). of health insurance coverage in 1983 (Health Insur- Recently, some insurance companies have begun using ance Association of America, 1984), and many people lifestyle factors, such as one’s smoking or exercise consider health insurance to be a necessity. The ma- habits, in assessing insurance risk. jority of health insurance policies are group policies, Controllable Risk Factors.—Smoking is considered received in conjunction with employment. These largely a voluntary activity, controllable by the indi- group health policies do not consider the health risks vidual, with strong actuarial evidence of significantly of the applicants to determine their insurability or reduced life spans. It is also generally accepted that their premiums. However, claims made on preexisting the primary health effects from smoking (e.g., cardio- health conditions are exempted for a period usually vascular disease, emphysema, and lung, esophageal, App. B—Privacy and Control of Genetic Patient Data 75

and bladder cancers) can be caused by smoking. Per- market. By using this information, they will be better haps the major drawback of using this type of lifestyle able to identify high-risk applicants and thus be able information is that it is self-reported and, therefore, to charge them proportionately higher premiums. not verifiable; since there is a price incentive to re- The adverse selection model, described below, port that one is a non-smoker, an applicant may not provides one explanation for why insurance com- be truthful. panies might wish to use genetic patient data in the Diet is also a known risk factor for development of underwriting process. In an insurance market, when certain types of diabetes, arthritis, and susceptibility there is no distinction made between the risks of the to colonic and breast cancers. Alcohol ingestion is applicants, there is a tendency for those who know associated with liver cirrhosis, esophageal and stom- they are at risk to purchase the highest coverage they ach cancers, and more than a dozen neurological syn- can afford. With more of these high-risk clients, in- dromes. surance company costs will increase, because the com- Uncontrollable Risk Factors.—Until a 1983 Supreme pany will be paying more claims. The increase in costs Court Decision, it was common practice in the insur- tend to drive up the insurance premiums, causing low- ance industry to use the gender of the applicant to risk clients to leave, this results in a pool of high-risk determine the premium. While that practice continues clients, paying high premiums. If another type of in- in the underwriting of individual policies, it is no surance were available that differentiated applicants longer allowable in group health, or employee bene- on the basis of risk, insurance companies could make fits, policies. (I. Katz Pinsler, ACLU, personal commu- a profit by offering it as an option (McGill, 1984). The nication, 1984). In contrast to lifestyle factors, one’s use of genetic patient data could help insurance com- gender is genetically determined and is not under panies counter this adverse selection phenomenon one’s voluntary control, but there is strong actuarial which can lead to high rates. evidence that women tend to live longer than men. The question of fairness remains, however, and the Gender is verifiable, which makes it relatively easy to crux of the issue is whether it is more fair for those use as a determinant. Some actuaries, however, ques- individuals with high risks to pay proportionately high- tion the use of gender, claiming that other factors such er rates or for all individuals to pay the same rate, as smoking, lifestyle, work habits, or competitive regardless of risk. In the first case, market forces will behavior maybe the cause of the mortality differences act to differentiate people on the basis of the risk they (Cummins, et al., 1983 p. 86), (Business Insurance, present to the insurance company, and may lead to 1981). groups of individuals unable to purchase insurance at The race of an applicant is not used to determine an affordable price. This type of situation may seem the premium, although the criteria are similar to the fair when it concerns something over which an indi- case of gender: one’s race is not under one’s own con- vidual has some control, such as one’s smoking habits, trol, but although there is actuarial evidence for mor- but the fairness issue becomes more difficult when tality differences between races, it is difficult in prac- it involves something over which one has no control, tice to identify distinct races because of the degree such as one’s genetic complement. of racial mixing. Insurance companies argue that the In the latter case, where everyone pays the same actuarial differences between races are due to socio- rate, low-risk individuals would be subsidizing high- economic differences and not to race, per se, and that risk ones. In either case, one group will be harmed, these factors are already considered in the actuarial and society needs to determine whether the low-risk process. Also, several States have prohibited the use or high- risk individuals will bear the burden. A com- of race in insurance underwriting (Cummins, et al., promise could be made using the U.S. Social Security 1983 p. 90). system as a model. In this system, contributions are Some factors with genetic components are used not actuarially equal to benefits, but the level of to determine the insurance premium, such as a family benefits is related to the amount contributed (Cum- history of heart disease. The criteria for using genetic mins, et al., 1983). patient data are similar to those for race and market Impacts of Using Improved Genetic Patient Data.— since one’s genetic complement is not voluntary. At Increased screening for genetic diseases could lead to present, however, most genetic diseases cannot be numerous groups of individuals that are substandard verified before they are expressed. risks, uninsurable, or who must pay prohibitively high Efficiency and Equality.—Insurance companies, as rates. At present, diseases or health conditions that profit-maximizing firms, have an incentive to use any already exist carry more weight in the underwriting readily available genetic patient data because it will formulae than those conditions which are just statis- allow them to function more efficiently in the free tical probabilities. If reliable genetic patient data were 76 Human Gene Therapy—Background Paper

available at low cost to use in insurance underwriting, ance rates—a profit-maximizing company has an in- however, more weight might be placed on them. For centive to reduce the incidence of work-related dis- example, if an applicant has expressed polycystic kid- ease as long as the costs of the reduction are lower ney disease, he or she is likely to be denied insurance. than the costs of the disease (Murray, 1983). However, since this disease is not expressed until later Because the expression of a genetic disease is fre- in life, an individual can carry the gene for the dis- quently thought to be determined by a combination ease and still obtain insurance, since there is no way of genetic and environmental factors (Harsanyi, 1981), to detect the gene at present. If the gene could be companies may have the ability to change specific envi- detected at an early age and one could say with high ronmental factors which otherwise enhance the pos- certainty that a person would develop polycystic kid- sibility of disease expression. Availability of genetic ney disease, then such tests might be used to deter- data on employees could then lead to companies assist- mine insurability. Further questions arise concerning ing those employees in remaining healthy. the use of tests that are under development, are not But what if the cost of the disease is higher than that perfectly accurate, or are prohibitively expensive. For of the reduction? Or if there is no known way to re- example, if a test were developed which indicated the duce incidence? Or if a company is disinclined to in- presence of a gene but not whether it would result stitute changes due to either inconvenience or cost? in disease,5 should the results of the test be used in The use of genetic patient data under these circum- the underwriting process? Three States, Florida, Mary- stances could lead companies to discriminatory hir- land, North Carolina, (Case, Health Insurance Associa- ing, promotion, or lay-off policies. In this light, the tion of America, personal communication, 1984) question once again arises as to whether companies already specifically prohibit health insurance com- should have general access to genetic patient data. panies from discriminating against sickle cell carriers. Title VII of the amended 1964 Civil Rights Act, and The increased use of genetic patient data in the sections 503 and 504 of the 1973 Rehabilitation Act underwriting process has significant legal implications. govern employment rights. The former prohibits em- Since several genetic diseases are linked closely with ployment discrimination on the basis of race, color, race, (see table B-1) if an insurance company uses religion, sex, or national origin. The latter prohibits genetic patient data to compute the health risks of ap- discrimination against otherwise qualified handi- plicants, it would have a disparate impact on the af- capped individuals by employers who are Government fected races. As genetic markers become more re- contractors or recipients of Federal assistance. fined, it may become increasingly difficult to separate Currently, the term ‘handicapped individual’ is de- the prevalence of specific genetic diseases from race. fined in section 503 as “any person who: 1) has a phys- Therein lies a potential conflict with current or future ical or mental impairment which substantially limits civil rights laws. one or more of such person’s major life activities, 2) The role of Federal and State Governments in con- has a record of such an impairment, or 3) is regarded straining access to genetic patient data may increase as having such an impairment.” Equally, in section 504, in proportion to the amount readily available. Patient an employer receiving Federal financial assistance may protection will be afforded by case law, but some not make preemployment inquiry about whether the aspects of how genetic patient data are specifically applicant is handicapped or about the nature and handled (in contrast to other personal or medical in- severity of an existing handicap unless a preemploy- formation) may depend on new Federal or State reg- ment medical examination is required of all applicants ulations. Public policy on genetic patient data turns, and the information obtained from the examination in part, on whether it is classed as a basis, like race, is relevant to the applicant’s ability to perform job- for civil rights protections. As the availability of genetic related functions. Both sections serve to limit the use patient data grows, pressures to use it and disclose of discriminatory preemployment examinations and it to third parties will also likely increase. Legislatures tests, but it must nevertheless be determined whether may wish to consider new laws to redress misapplica- genetic trait is a handicap and whether screening pro- tions or to cover areas not clearly defined in case law. cedures are job related. These statutes indicate that individuals are not to DISCLOSURES TO EMPLOYERS be discriminated against on the basis of some im- Because of the significant costs of occupational mutable characteristics and that their abilities are to illness— including the time lost from work, the cost be judged on an individual basis. Since genetic screen- of training replacements, and increased health insur- ing could result in employment discrimination against

%ince most diseases at-e due to a combination of genetic and emrironmental groups of individuals with particular inherited traits, factors, genetic tests may eventually prove to be mostly of this type one question that arises is whether such discrimina- App. B—Privacy and Control of Genetic Patient Data 77

Table B-1.—Genetic Diseases Found in Higher Prevalence Among Specific Racial or Ethnic Groups

Condition Prevalence Amyloid nephropathy associated with familial Mediterranean fever ...... 1:3,000Sephardic Jews Aspartylglycosaminuria ...... 70-100 cases in Finland Cystic fibrosis ...... 1:2,000 Caucasians Diabetes mellitus, type 2 (insulin-dependent, ketosis- resistant) ...... 1:130 Caucasians, uncertain in blacks Dubin-Johnson syndrome ...... 1:1,300 Iranian Jews Essential fructosuria...... 1:130,000; more common in Jews Galactosylceramide Iipidosis (globoid cell Ieukodystrophy; Krabbe’s disease)...... 1:50,000 in Sweden Gaucher’s disease, type I ...... 1:2,000 U.S. Jews Glucose-6-phosphate dehydrogenase (G6PD) deficiency; multiple allelic disorders, including mild A-type and severe Mediterranean type...... A-type: 1:11 U.S. blacks (males) Mediterranean type: common in Africa, Middle East and other Mediterranean countries Gyrate atropy of the choroid and retina ...... 1:50,000 in Finland Hereditary fructose intolerance ...... 1:20,000 in Switzerland Hereditary spherocytosis, several types ...... 1:5,000 Caucasians Hermansky-Pudlak syndrome ...... 1:60,000 Caucasians 1:5,000 Puerto Ricans Intestinal Iactase deficiency ...... 1:10 Caucasians, majority of Asians, Africans, and U.S. blacks are affected Niemann-Pick disease ...... 1:25,000 U.S. Jews Nonketotic hyperglycinemia ...... 1:250,000 in United States 1:12,000 in Northern Finland Occulocutaneous albinism, tyrosinase-negative type . . . . . 1:39,000 Caucasians 1:28,000 blacks Occulocutaneous albinism, tyrosinase-positive type ...... 1:37,000 Caucasians 1:15,000 blacks 1:150 in certain American Indians Pentosuria ...... 1:2,500 Eastern European Jews Primary gout: idiopathic ...... 1:500 in Western populations 1:50 in American males by age 50 1:10 in males in some Polynesian groups 1:25 in females in some Polynesian groups Sickle cell anemia ...... 1:500 U.S. blacks (newborns) Tay-Sachs disease...... 1:3,000 U.S. Jews Thalassemia, multiple allelic disorders ...... High frequency in Mediterranean, African, and Asian populations Tyrosinemia, type I (hepatorenal tyrosinemia; tyrosinosis) ...... 1:10,000 French Canadian isolate Variegate porphyria ...... Common in South Africa; rare in other parts of the world Xeroderma pigmentosum, multiple types involving multiple gene loci ...... 1:25,000 in Egypt SOURCE: Stanbury, 1983; as amended by Bowman, personal communication, 1984. tion is prohibited by these two acts (OTA, 1983). If they tainly cannot be classified as a “hazard” (OTA, 1983). are judged not to prohibit genetically based discrimina- Yet genetic testing might become the basis for employ- tion, another question raised is whether additional fed- ment discrimination, or harm to employees. eral legislation will be forthcoming. In this light, it is significant to note that it is com- The 1970 Occupational Safety and Health Act (OSHA), mon practice for employees to sign a blanket waiver which requires employers to maintain a workplace allowing the company to gain access to all medical free from recognized hazards, does not specify the records it deems necessary. Employees generally “have means by which that requirement can be met. For ex- little genuine expectation of true confidentiality as to ample, it neither supports the argument that genetic employment medical records” (OTA, 1983). Any duty testing is required nor that genetic testing is pro- to the confidentiality of the patient is based on a phy- hibited. Although the results of genetic testing could sician-patient relationship, and the traditional view is have an adverse affect on particular employees, it cer- that a physician-patient relationship does not exist be- 78 . Human Gene Therapy—Background Paper

tween an employee and an employer-provided physi- DISCLOSURE TO THE GOVERNMENT cian. Some courts take a view that the existence of a The government will likely play an important role physician-patient relationship is dependent on the con- in issues relating to genetic patient data both as a sig- text of the health care provided. If the physician-pa- nificant user of information and as a body acting to tient relationship does not exist, neither does the duty control the access to that information. of confidentiality, and so the company generally may The major objective of government in using medi- have access to the medical records of its employees. cal information is the protection of the public health. There are also few common law restrictions on the For example, by collecting statistics on the frequency disclosure of genetic patient data to parties outside of and incidence of various diseases, the government per- the company, except for several State and Federal haps can take measures against those diseases in the restrictions. For example, California requires employ- future, perhaps by mobilizing health care efforts in ers to establish procedures to protect the privacy of particular areas. Other likely government uses of medical records, and records may not be released genetic patient data include: without the consent of the employee. Because of the providing information about medical costs, potential harm to the employee arising from disclo- developing policies to better allocate health sure, legislators may wish to anticipate the outcome resources, and of the increased use of genetic information by employers. . identifying diseases which merit additional re- Unauthorized Access.—Because of the use of com- search. puters to maintain health records, there has been a growing concern for the security of the information, For these purposes, the identity of the individual is especially in light of the reports of computer crime. not important, and so all identifying pieces of informa- These concerns are not unique to the health care field, tion can be culled from the record. For other purposes, since every major sector of the economy is relying such as tracking individuals with specific genetic dis- more on the computer for the maintenance of records. eases or doing epidemiological research, however, it Genetic patient data may not be as obvious a candi- is important to know the identity of those at risk. In date for computer theft as would be valuable trade the interests of privacy and security, the records may secrets, but patient records at Memorial Sloan-Ketter- be coded and the identifying information may be ing Cancer Center have already been broken into (Mar- stored in a separate file, but the identity of individuals bach, 1983), and so the possibility of unauthorized or must still be accessible. In this instance, privacy can inadvertent access should not be discounted as greater be retained by authorizing only one, or a few, disease amounts of genetic patient data become stored. centers to follow individual patients. One solution to the problem of unauthorized access Because of the growing amount of information col- is to remove any identifying data from the record and lected and used by the Federal Government, and be- keep it in a separate file. Then codes could be used cause of improvements in information storage and re- to match the individuals to their records. Another solu- trieval technologies in the foreseeable future, Congress tion is to extend the concentric circle model of privacy passed the Privacy Act of 1974 to set a policy for the to include the genetic patient data stored in computer appropriate use of personal information. The Act files. The information could carry different access states that “The right to privacy is a personal and fun- codes, so that information could be accessed only by damental right protected by the Constitution of the those physicians who need to know. Different individ- United States, ” and that in order to “protect the uals would therefore have access to different levels privacy of individuals identified in information systems of private information, but this would not obviate the maintained by Federal agencies, it is necessary and need for patient control of disclosure of information proper for the Congress to regulate the collection, to third parties (Walters, 1983). These safeguards, maintenance, use, and dissemination of information while protecting the privacy of individuals, might also by such agencies” (Privacy Protection Study Commit- have the detrimental effect of making it more diffi- tee, 1977). The Act describes in detail the conditions cult for physicians to use the information in the med- of disclosure and access, as well as agency require- ical record. The experience of research on Huntington ments and rules. The Act forbids the disclosure of any Disease suggests that it is possible, by careful atten- records to any person or agency, except with a writ- tion to data entry and access restriction, to provide ten request by, or with the prior request of, the indi- aggregate data while protecting individual privacy vidual to whom the record pertains. Violations of the (Wexler, personal communication, 1984). Act can lead to a civil liability. App. B—Privacy and Control of Genetic Patient Data 79

The Federal Government is involved in providing employment and underwriting situations. Some States funding for genetic testing and counseling, thus assist- have already forbidden the use of such data as gen- ing in the process of collecting genetic patient data. der, age, handicaps, or other impairments in the The government can also serve as an effective forum underwriting process (Cummins, et al., 1973). to discuss the ethical, legal, economic, and social General education is an issue of Federal, State and aspects of genetic information. Since there are many local interest, necessary so that all people can have different groups involved in balancing the issues of an understanding of genetics sufficient to understand privacy and access, the Federal Government can en- the complex issues of genetic patient data (President’s sure that these issues are included in the decisionmak- Commission, 1983; Rowley, 1984). Some schools have ing process. responded to this need by making genetics a major The States also have the authority to compile and focus of their biology courses. Genetic education is an store genetic patient data that is of potential benefit issue for health care providers, as well. The teaching to the public health (Reilly, 1977 pp. 250-252). Several of genetics occurs primarily’ during the first 2 years States have written laws that regulate the type of in- of medical school, with little integration of genetics formation that can be collected and the procedures into the practical side of clinical training (Rowley, through which disclosure can be made (Reilly, 1977 1984). As the technology for identifying genetic dis- pp. .252 -256) The States also have control over the ease improves, it is important that physicians become business practices of various industries including in- aware of that technology and how to use it with pa- surance companies, and they may determine the pro- tients. priety of using genetic patient data in different

Conclusion

Public policy on genetic patient data is centered on Public policy on genetic patient data attempts to con- determining the rights of privacy and access, pitting in- trol access so that individual privacy is protected. This dividual autonomy against relatives’ or third parties’ effort may include support of data storage methods needs for information. The legitimacy of others’ needs that are coded so that epidemiologic research and re- are determined by the potential benefits to relatives, search priority assessment may be performed with- health providers, insurers, employers, or the general out jeopardizing individual privacy. Legislation may public compared to potential harm to the patient from be required to guide genetic data collection agencies disclosure, Several factors are included in such assess- in what constitutes appropriate disclosure of informa- ments, including the seriousness of the genetic con- tion and to act as a deterrent to unauthorized access. dition, the genetic relationship between interested par- Public policies may be required that would strengthen ties, and the probability of preventing harm or individual’s control over access to their genetic data. promoting good by disclosure. When no genetic rela- In contemplating new legislation, care must be taken tionship exists, as in the case of insurers and to ensure that controls are not so strict that the genetic employers, issues of fairness arise. Continuing public patient data cannot be used for legitimate and lifesav- scrutiny may be instrumental in the evolution of ing purposes. deciding on a hierarchy of conditions and people for whom disclosure of genetic patient data is important (Rosenfeld, 1984). Appendix C Working Group on Human Gene Therapy Recombinant DNA Advisory Committee National Institutes of Health

LeRoy Walters, Chairman Director, Center for Bioethics Kennedy Institute of Ethics, Georgetown University W. French Anderson Robert F. Rich Laboratory of Molecular Hematology School of Urban and Public Affairs National Heart, Lung, and Blood Institute Carnegie-Mellon University National Institutes of Health Harold Varmus Judith Areen Department of Microbiology Georgetown University Law Center University of California Alexander Capron Anne R. Witherby The Law Center Public Representative University of Southern California Executive Secretary James F. Childress The Wilson Center William J. Gartland, Jr. Smithsonian Institution Office of Recombinant DNA Activities Samuel Gorovitz National Institute of Allergy and Department of Philosophy Infectious Diseases University of Maryland National Institutes of Health Susan K. Gottesman Consultant Laboratory of Molecular Biology National Cancer Institute Howard M. Temin Clifford Grobstein Department of Oncology Department of Science, Technology, and University of Wisconsin Public Affairs University of California, San Diego Liaison Representatives Maurice J. Mahoney Charles McCarthy Department of Human Genetics Office of Protection From Research Risks Yale University Office of the Director Robert E. Mitchell (ex officio) National Institutes of Health Attorney at Law Henry I. Miller Norwalk, CA National Center for Drugs and Biologics Arno G. Motulsky Food and Drug Administration Department of Medicine University of Maryland Robert F. Murray Division of Medical Genetics Howard University

ao Appendix D Acknowledgements

Preparation of this background paper has been reviewed the report. Barbara Filner at the Institute greatly assisted by scientists, medical professionals, of Medicine of the National Academy of Sciences made journalists, members of the clergy, and other inter- several helpful suggestions. Finally, many scientists, ested parties. Special thanks are extended to members health professionals, attorneys, ethicists, journalists, of the Human Gene Therapy Advisory Panel that con- and other interested parties assisted OTA in prepara- vened at OTA on September 25, 1984, and others who tion of the document. These include David Martin, attended that meeting. Several other groups also de- Nancy Wexler, Zsolt Harsanyi, William Nyhan, Jeremy serve special mention. Many workers at the National Rifkin, Yale Bohn, Jeffrey Fox, Elena Nightingale, A. Institutes of Health, notably Elizabeth Milewski, Rachel L. Beaudet, Kenneth Ryan, Philip Leder, Thomas Levinson, and Bernard Talbot, critically reviewed Maniatis, Duane E. Jeffery, Monte Turner, Mark Skol- some sections of the report. Several members of the nick, Leroy Hood, Leon Rosenberg, Leon Kass, and Human Gene Therapy Working Group of the Recom- Richard McCormick. Two Scandinavian reviewers also binant DNA Advisory Committee at NIH were also submitted comments: Ole Johan Sandvan and Bertil quite helpful, including Howard Temin (consultant to Wennergren. Those on the OTA staff thank all who the group), Judith Areen, Alexander Capron, James assisted us. Those who contributed should not, how- Childress, Samuel Gorovitz, Anne Witherby, Harold ever, be construed to agree with our conclusions or Varmus, Arno Motulsky, and Clifford Grobstein. Many interpretations, and should not be held responsible for at the Food and Drug Administration, in addition to mistakes or other errors. the two representatives on the Advisory Panel, also

81 ———

Appendix E List of Abbreviations and Glossary

Abbreviations protocols to ensure compliance with Federal Human Subjects Protections, and report non- compliance with the Protections to appropri- ADA — Adenosine deaminase, an enzyme whose ate institutional officials and the Secretary absence leads to metabolic errors that in (Code of Federal Regulations, 1983). turn inhibit the bodies’ immune defenses. mRNA — Messenger RNA (see Technical Notes). ADA deficiency is a rare disorder caused by NIH – National Institutes of Health, Public Health genetic mutation that is inherited as an auto- Service, U.S. Department of Health and somal recessive trait. It is not the same dis- Human Services. order as PNP deficiency, although there are OCT – Ornithine carbamoyl transferase (or orni- some similarities. thine transcarbamylase), an enzyme that cDNA — Complementary DNA, DNA made from a mediates metabolism in the urea cycle, and messenger RNA template (see Technical whose deficiency is inherited as an X-linked Notes). trait. DNA — Deoxyribonucleic Acid (see Technical Notes). OSTP – Office of Science and Technology Policy, EAB — Ethics Advisory Board, established under the reporting directly to the President. Secretary of Health and Human Services to OTA – Office of Technology Assessment, U.S. advise the Secretary on ethical issues related Congress. to public policy. There can be one or more PKU – Phenylketonuria, a disorder caused by de- such boards (Code of Federal Regulations, ficiency of an enzyme, phenylalanine hy- 1983). None presently exist, despite Federal droxylase, that metabolizes one amino acid regulations. (phenylalanine) to another (tyrosine). It is in- HPRT – Hypoxanthine-guanine phosphoribosyl herited as an autosomal recessive trait. transferase (or hypoxanthine phosphori- PNP – Purine Nucleoside Phosphorylase, an en- bosyl transferase), an enzyme whose com- zyme whose absence leads to metabolic er- plete deficiency leads to Lesch-Nyhan syn- rors that in turn inhibit the bodies’ immune drome, and whose partial absence leads to defenses. PNP deficiency is caused by a rare gout. HPRT deficiencies are inherited as X- genetic mutation inherited as an autosomal linked traits. recessive trait different from ADA defi- IBC — Institutional Biosafety Committee, estab- ciency. lished at a university hospital, private firm, RAC – Recombinant DNA Advisory Committee, con- or other research center. IBCs supervise re- stituted at the National Institutes of Health search protocols to ensure compliance with to advise the Director of NIH on experiments Federal Guidelines for Research Involving involving recombinant DNA and molecules Recombinant DNA Molecules. In the case of derived from recombinant DNA. Human Gene Therapy, this will involve re- RFLP – Restriction fragment length polymorphism, view also by the RAC and the NIH Director a phenomenon involving variation in the before approval to commence experiments. length of DNA cut by specific enzymes that IRB — Institutional Review Board, established at a permits location of genes of interest, includ- university, hospital, private firm, or other re- ing disease-related genes (see app. A). search center. IRB’s must be composed of 5 RNA – Ribonucleic Acid (see Technical Notes). members, at least one of whose primary in- tRNA — Transfer RNA (see Technical Notes). terests are in nonscientific areas and one TSD — Tay-Sachs disease, an autosomal recessive member neither affiliated with the institu- disorder caused by deficiency of the enzyme tion nor in the immediate family of anyone hexosaminidase A. who is so affiliated. IRBs supervise research UCLA — The University of California at Los Angeles.

82 App. E—List of Abbreviations and Glossary • 83

Glossary can be grown in cell culture and either analyzed biochemically or cytogenetically to detect a variety (over one hundred) of hereditary diseases. Achondroplasia—a defect in the formation of car- Anencephaly-–a congenital defect characterized by tilage at the ends of long bones (femur, humerus) the absence or extreme reduction in size of the that often produces a type of dwarfism. There are brain and spinal cord. It is usually due to complex a number of hereditary forms, the most common developmental malformations rather than a simple of which is an autosomal dominant. genetic defect. ADA deficiency—an autosomal dominant disorder Antibody molecule-protein molecules manufac- caused by deficiency of the enzyme adenosine de- tured in the body that serve to recognize and aminase, and resulting in inhibition of the bodies’ destroy cells identified as foreign. The antibody defenses. molecule is a tetramer, composed of two large, Allele-one of several possible alternate forms of a heavy chain molecules and two light (kappa or lamb- given gene. da) chain molecules. The ability to bind to different Alpha fetoprotein—a fetal protein found in amniotic antigens (molecules that stimulate the production fluid that indicates, by its presence and concentra- of antibodies) resides in antibodies. tion, the presence of certain fetal defects (e.g. Antigen—a molecule, usually a large protein or car- anencephaly; spina bifida). bohydrate, which when introduced into the body Alpha globin mRNA deficiency—an insufficiency stimulates the production of an antibody that will in the messenger RNA coding for the alpha chain react specifically with the antigen to remove it. of hemoglobin. Aneuploidy—a defect of chromosome number. Nor- Alpha-1-antitrypsin deficiency—a recessive mal sexual organisms are diploid; that is, they have heritable disease due to the lack of a protein inhib- two complete sets of chromosomes, one of paternal iting enzyme, alpha-1-antitrypsin. Death is usually origin and one of maternal origin. Defects of ploidy due to degenerative lung and liver disease. can be either of individual chromosomes, where one Alpha thalassemia—an hereditary disease due to an more or one less is present than normal (trisomy; insufficiency in the number of alpha hemoglobin monosomy), or of entire chromosome sets (e.g., molecules in the blood. It is usually caused by the triploidy). deletion of a portion of the gene coding for the alpha Argininemia—a recessive genetic defect marked by hemoglobin molecule. severe mental retardation and various neurological Alzheimer disease—a progressive brain disease disorders. It is due to an excess of arginine in the marked by progressive dementia (loss of memory blood and spinal fluid, this being caused by de- and higher mental functions) and associated with creased activity of the enzyme (arginase) that nor- characteristic changes in and near nerve cells: senile mally degrades this molecule. It was suggested a plaques and neurofibrillary tangles. The evidence decade ago that argininemia could be treated in suggests the disease can be caused in several dif- humans by deliberate infection with the Shope rab- ferent ways: a hereditary form exists, but its preva- bit papilloma virus, which had been shown to re- lence is uncertain; slow acting infectious agents may store arginase activity of deficient cells in tissue play a role; the body’s immune system may react culture. against the brain; specific populations of nerve cells Arginosuccinate synthetase deficiency—see Cit- may die; and environmental toxins (ionic aluminum rullinemia. or silicon) may be involved; or some combination Arteriosclerosis (hardening of the arteries)--a of factors. condition in which the walls of blood vessels become Aminoaciduria (branched chain; and ketoacid- thickened and hardened due to a number of differ- uria)—any of a large class of diseases marked by ent pathological conditions. The causes are multi- the accumulation of various amino acids (branched ple and complex, and often incompletely known. chain or ketoacids) in the blood. Symptoms vary There is good evidence that genetic factors are with the specific compounds involved, each presum- sometimes involved. ably the result of different defective enzymes in the Arylsulfatase B deficiency—an autosomal recessive relevant metabolic pathways. disorder of lipid metabolism caused by a deficiency Amniocentesis—the process of withdrawing a sam- in the production of the enzyme arylsulfatase B. A ple of the amniotic fluid surrounding the fetus in form of metachromatic leukodystrophy, the symp- utero through a needle into a syringe. The fluid toms are severe physical changes including hydro- taken (usually 2 to 8 milliliters, or cubic centimeters) cephalus, with death usual by the late teens. contains cells shed by the developing embryo. These Atherosclerosis—the most common form of arterio- 84 Human Gene Therapy—Background Paper

sclerosis in which there are localized deposits of Blastocyst—the developmental stage (in a mammalian fatty material (lipids) in the walls or the chamber embryo) immediately following the morula. It con- (lumen) of blood vessels. It can be the result of sists of an outer layer (the trophoblast) containing defects in lipid metabolism, many of which are a cell mass attached to the inner wall of the interior genetic in nature. cavity, or blastocoele. (See Technical Notes. ) Auto-immune disease—a disease in which the Carcinogen—an agent or chemical that causes cancer. body’s defenses fail to distinguish its own tissue Carrier (silent carrier)—an individual carrying a from foreign matter (’(self” from “non-self”) and at- genetic defect and capable of transmitting it to off- tack it. The causes are probably errors in gene reg- spring, but who does not show the defect him/her- ulation, and there are clearly hereditary forms of self. Most often, a carrier is heterozygous for a this disease. A common form is lupus erythema- recessive allele, that is, carries only one of the two tosus, in which the connective tissues of the body copies of a gene necessary for the trait to be mani- (collagen especially) are progressively destroyed. fest. It is possible, however, for an individual to Autosomal dominant—a genetic trait (or a gene) car- carry a dominant allele that is not expressed and ried on one of the autosomes that produces an ob- thus to transmit the trait to offspring while never servable phenotype even if present in only one copy showing it him/herself. (i.e., of the two alleles present for any given gene, Chorionic villus biopsy—a technique of ante-natal if only one of them is a dominant it will be expressed diagnosis by which a sample of tissue is taken from regardless of whether the other is dominant or the placenta (whose cells are of fetal origin) and recessive). analysed to detect the presence or absence of cer- Autosomal recessive—a genetic trait (or gene) car- tain hereditary defects in utero. ried on one of the autosomes that must be present Chromosomal disorders-any of a great variety of in two copies (both of the alleles present must be pathological conditions associated with abnormal- of the same type) in order for the gene to be ex- ities of the chromosomes, whether of number (aneu- pressed and the trait seen in the phenotype. ploidy) or structure (insertions, deletions, rear- Autosome—any chromosome other than the sex rangements). chromosome. Chromosome (colored body)–-so named by early Azacytidine (5-azacytidine)-a drug used in cancer researchers because they stained very darkly when therapy that has also been used experimentally to colored with certain dyes, chromosomes are the promote expression of hemoglobin F genes (to re- location of hereditary (genetic) material within the place defective Beta globin genes) in patients with cell. This hereditary material is packaged in the thalassemia and sickle cell disease. form of a very long, double stranded molecule of Bacteriophage (phage)—a virus that infects a bac- DNA surrounded by and complexed with several terial cell. Phage consist of a core of genetic mate- different forms of protein. Genes are found ar- rial (DNA or RNA) carrying the particle’s genetic in- ranged in a linear sequence along chromosomes, as formation which is surrounded by a protein coat is also a large amount of DNA of unknown function, or capsule. When a phage infects a host cell, the cell but that may serve simply to help keep one gene machinery that manufactures protein in response separated from its neighbors. to genetically encoded instructions is commandeered Citrullinemia--an autosomal recessive defect whose by the phage and used to produce offspring phage. clinical symptoms are associated with a deficiency These are released when the bacterium dies, liber- in the enzyme argininosuccinate synthestase. Symp- ating from 100 to 10,000 new phage particles per toms include ammonia intoxication, severe vomiting, infected bacterium. and mental retardation. Beta globin--one of the several types of hemoglobin Cleavage–the stage of cell multiplication immediately molecules. In normal adult humans hemoglobin is after fertilization of the egg. It lasts until the cells a compound molecule formed of four protein sub- begin to segregate and differentiate, producing a units (globins) and a heme group. The four globins blastula and then gastrula. consist of two alpha and two beta molecules. Complementary DNA–- (cDNA)–DNA synthesised Beta thalassemia—a hereditary genetic defect from a messenger RNA template rather than the caused by a deletion or alteration of a portion of usual DNA template. cDNA is often used as a DNA the gene coding for the beta globin molecule. The probe to help locate a specific gene in an organism. result is an insufficiency in the number of beta The advantage of cDNA over mRNA as a probe is globin molecules, which leads to abnormal hemo- that the mRNA can be used to identify a specific globin, gene product (e.g., an enzyme important to the App. E—List of Abbreviations and Glossary . 85

cause of a hereditary disease) and then to produce by the presence of all or part of an extra 21st chro- a DNA probe (more stable and more easily handled mosome. The symptoms are mental retardation, than RNA) to find the gene responsible for the here- congenital heart defects, immune system abnormal- ditary disease. ities, various morphological abnormalities and a re- Conceptus—a fertilized egg; an egg after conception. duced life expectancy. Down syndrome is one of Cystic fibrosis—an autosomal recessive disorder in those diseases that has been most clearly shown to which the glands do not function normally. Most increase in frequency with advancing maternal age. often seen in children and young adults, it is usu- (Down syndrome has been known by several equal- ally lethal. Death is due to excess mucus in the lungs ly inappropriate common names in different cul- and pancreatic insufficiency. tures, e.g. ‘(Mongolism” in the West and “round-eye” Cytogenetics—the study of chromosomes and their syndrome in the Orient. ) behavior in the cell: what they look like, how many Drosophila—a genus of diptera, or two-winged in- there are, how they are replicated and distributed sects, that has been extremely useful in genetic to daughter cells (mitosis) or among gametes studies of nearly every sort. This is because of the (meiosis). unique collection of advantages afforded those Cytotoxic agents-chemicals, compounds or other working with the organism, which include a short agents that can cause cell death for any of a variety generation time (so that many generations can be of reasons. studied in a fairly short period of time) a high fecun- Dementia—loss of higher mental functions: memory, dity (thousands and even millions can be realistically reasoning ability, speech, etc. studied in a reasonable length of time) and the ex- Diabetes mellitus—a disorder of carbohydrate me- tremely favorable giant polytene chromosomes in tabolism marked by elevated blood sugar due to in- the salivary glands of the larvae, which make it pos- adequate insulin production. sible to correlate genetic phenomena with morpho- di-methyl adipimidate–an experimental compound logical changes in the chromosomes, and follow used to prevent sickling in the red blood cells of pa- these characters through numerous generations tients with sickle cell anemia. and experimental crosses. Also known as “fruit DNA (deoxyribonucleic acid)—the molecule con- flies, ” this genus is generally harmless, and not to taining hereditary information in all but the most be confused with the ‘(true fruit-flies” or tephritids, primitive organisms (some viruses, that use RNA). which are severe agricultural pests. The molecule is double stranded, with an external Duchenne Muscular Dystrophy—see Muscular “backbone” formed by a chain of alternating phos- dsytrophy, Duchenne type. phate and sugar (deoxyribose) units and an inter- Dwarfism-a pathological condition of abnormally nal ladder-like structure formed by nucleotide base- short stature. Some cases are known to be heredi- pairs held together by hydrogen bonds. The nucleo- tary, while others result from disease or metabolic tide base pairs consist of the bases adenine (A), dysfunction. cytosine (C), guanine (G) and thymine (T) whose Electrophoresis--a technique for separating differ- structures are such that A can hydrogen bond only ent molecules based on their differential movement with T, and C only with G. The sequence of each in an electric field. This differential movement is a individual strand can be deduced by knowing that complex function of molecule size, shape, and net of its partner, This complementarily is the key to electrical charge. the information transmitting capabilities of DNA. Embryogenesis—the process of cell growth that pro- (See Technical Notes.) duces an embryo from the proper mixture of a zy- DNA probe–a molecule (usually a nucleic acid) of gote, nutrients, and time. known structure and/or function that has been Expression—the process by which the blueprint con- tagged with some tracer substance (a radioactive tained in DNA is converted into the structures and isotope or specific dye-absorbing compound) that biochemical mechanisms present and operating in is used to locate and identify a specific gene or re- a cell. gion of a chromosome or portion of the genome. Expressivity—a term referring to the degree to Dominant--a gene that produces a visible effect even which a gene is manifest in an individual. Genes for when present in heterozygous condition; each dip- some traits (e.g., curliness of hair) may vary in the loid cell contains two copies (alleles) of the gene at extent or severity to which they are seen in different any specific locus. An allele that is expressed regard- individuals. Genes known to be manifest in different less of the nature of its companion allele is said to degrees in different individuals are said to show dif- be dominant. ferential or variable expressivity. Down syndrome—a chromosomal disorder caused Fabry disease—an X-linked (the gene is located on

86 Human Gene Therapy—Background Paper

the X chromosome) hereditary disease of lipid me- Genetic marker-any character that acts as a tabolism. Symptoms are a particular type of skin le- signpost or signal of the presence or location of a sion, kidney disease (the usual cause of death) and gene, chromosome, or hereditary characteristic in a variety of neurological and biochemical abnor- an individual, a population, chromosome or a DNA malities. molecule. For example, the phenotype of male sex Fetoscopy--a procedure whereby the fetus is visually is a reliable indicator of the presence of the gene examined with a fiber optic instrument while still for H-Y antigen, a cell surface protein found in all in utero. genotypic males. Galactosemia--an inborn error of metabolism Genome—the total genetic information contained in (genetic defect of an enzyme system) marked by the an organism’s genes. Also described as the total con- inability to digest galactose, a sugar produced (along tent of all the chromosomes in an organism. with glucose) in the digestion of lactose, the com- Genotype—the total of the genetic information con- mon sugar in milk and dairy products. The symp- tained in the chromosomes of an organism. Com- toms of galactosemia are an accumulation of galac- pare to the phenotype, or external or morphological tose and byproducts which leads to liver damage, appearance of an organism. For example, an indi- cataracts, and mental retardation. Some relief can vidual may have a heterozygous genotype for eye be achieved by limiting the dietary intake of milk color consisting of an allele for brown eyes (which and dairy products. is dominant) and an allele for blue eyes (which is Gametes—mature male or female reproductive cells— recessive) or a homozygous genotype, with two al- sperm or ova. Gametes of the opposite sex, when leles (both dominant) for brown eyes. In either case, fused, lead to the formation of a new, diploid the phenotype is the same: brown eyes. organism. Germ line—also known as “germinal tissue, ” it is the Gamma globulin—a large protein molecule found in tissue or cell lineage that produces gametes and is the blood that is very important to disease resis- used for reproductive purposes, as opposed to that tance. Individuals with a hereditary deficiency in tissue or those cell lineages (somatic tissue, or soma) the production of this molecule (gamma globuli- producing the bodily structures and tissues used for nemia) experience a decreased ability to withstand functions other than reproduction. bacterial and viral infections. Globin–a class of proteins most often associated with Gaucher disease–an autosomal recessive defect of processes of oxygen or gas transport (e.g., hemo- lipid metabolism found with higher frequency globin or myoglobin). among Ashkenazic Jews of Eastern European origin Hemochromatosis—a pathological condition charac- and their descendants. Symptoms include enlarged terized by abnormal deposits of iron throughout the spleen and liver and various neurological disorders. body; signs and symptoms include defects of the There are several different types, the two most com- liver, glucose metabolism, and heart function. mon being a chronic adult form and an acute juve- Hemoglobin—a complex molecule that serves as the nile form that often leads to early death. primary oxygen transport vehicle in vertebrates. It Gene—the portion of a DNA molecule that comprises is composed of a single iron molecule surrounded the basic, functional hereditary unit; a sequence of by four globin molecules, two each of two different DNA that produces a specific product. The fruit fly, types (two alpha globins and two beta globins in nor- Drosophila melanogaster probably has about 10,000 mal adult humans). genes, whereas man may have as many as 100,000 Hemoglobinopathies—a collection of different, he- genes. reditary disorders of hemoglobin structure and/or Gene modification—a process of genetic therapy in function (e.g., thalassemia, sickle cell anemia). which genes are altered in the living organism. It Hemophilia–a hereditary disease distinguished by is not yet possible, but is expected in the future. an abnormally long blood coagulation time. The im- Gene supplementation—a technique of genetic ther- portant genes are recessive, and are found on the apy in which “new” or repaired genes are intro- X-chromosome, making it X-linked; this means that duced into a cell by microinjection or a similar it is most often seen in males, and most often trans- process. mitted to offspring by asymptomatic females. Gene surgery—a procedure whereby a defective Heterozygous--each normal cell in the body carries gene is excised and removed from a cell. A normal two copies of any given gene; if these two copies gene may be substituted. (alleles) are different one from another, or alternate Gene transplantation—a technique of moving an en- forms of the same gene (e.g., blue v. brown eyes), tire gene from one organism into another. then the individual is said to be heterozygous at that App. E—List of Abbreviations and Glossary . 87

locus. If they are identical, the individual is homo- gonadal dysfunction (testicular atrophy; sterility), zygous. below average intelligence, and possibly some be- Homozygous--each normal cell in the body carries havioral abnormalities (although this is still disputed two copies of any given gene; if these two copies by some). (alleles) are identical to each other (e.g., both coding Lesch-Nyhan syndrome-an X-linked recessive for brown eyes) then the individual is said to be disorder characterised by compulsive self mutilation homozygous at that locus. and other mental and behavioral symptoms. It is Huntington disease—’’Huntington chorea”--a ge- caused by a defect in the gene that produces a par- netic disease that is not manifest until after birth ticular enzyme (hypoxanthine-guanine phosphori- (usually between the ages of 30 and 50) resulting bosyl transferase) important in metabolism. In the in death due to progressive degeneration of specific absence of this enzyme large amounts of uric acid brain tissues. The primary signs and symptoms are accumulate in the blood, leading to gout. The causal disorders of movement and dementia. relationship to the behavioral disorder is not yet un- Hydrocephaly—a developmental defect marked by derstood. an unusual accumulation of spinal fluid in the ven- Linkage—the association, in inheritance, of different tricles of the brain. The malformation caused by this genes due to their physical proximity on chro- fluid buildup usually retards brain development, mosomes. often resulting in mental retardation and, in severe Lipid metabolism–the process by which lipid (fatty) cases, early death. The condition can now be treated molecules are broken down or synthesised in the if diagnosed soon after birth. body. Hydroxyurea--an experimental drug used to pro- Liposome—a structure with a lipid membrane like mote expression of hemoglobin F genes (to replace that of a cell that can be filled with specific sub- defective Beta globin genes) in patients with stances and then used as a delivery vehicle to trans- thalassemia or sickle cell disease. port those substances to the interior of a target cell Hypercholesterolemia (familial)—a pathological by fusion with the cell’s own membrane. It is one condition of excess blood cholesterol that is in- of several potential delivery vehicles for use in gene herited as an autosomal dominant trait, therapy. Hyponatremia—a condition of low sodium concen- Lysosomal storage diseases—lysosomes are intra- trations in the blood. cellular organelles that contain enzymes capable of Immune deficiencies—any of a number of condi- digesting proteins and some carbohydrates. Lyso- tions (e.g., adenosine deaminase deficiency, purine somal storage diseases result from an accumulation nucleoside phosphorylase deficiency, or AIDS) re- of certain of these molecules caused by an insuffi- sulting from a failure or malfunction of the bodily ciency of a lysosomal enzyme. The symptoms and defense mechanisms, or immune system. prognosis vary with the specific enzyme involved. Immunoglobins—a collection of complex protein Marfan syndrome—arachnodacytly (“spider fin- molecules that play a vital role in the body’s immune geredness’’)--a single gene defect of which the symp- system. toms are abnormally long fingers and toes, abnor- Implantation—the process by which the fertilized malities of the eye lenses and heart. (Abraham egg (zygote) becomes attached to the wall of the Lincoln is thought by some to have suffered from uterus (endometrium) which then serves to nourish this disease). the embryo through growth and subsequent devel- Membrane fusion—a process by which the mem- opment. branes (outer walls) of two cells merge, thus creat- in utero (in uterus) preferring to procedures that ing one daughter cell from two parents. In contrast are performed or events that take place within the to fertilization by gametes, membrane fusion de- uterus . scribes the joining of somatic cells. One of the most in vitro (in glass) —meaning in the laboratory; in the productive results of membrane fusion technologies test tube. is the formation of hybridomas, wherein an anti- in vivo (in life) —meaning in the living, intact body-producing white blood cell (leucocyte) is fused organism. with a tumor cell to produce a daughter cell that Klinefelter’s syndrome—a chromosomal abnormal- can generate very large amounts of a specific an- ity in human males. In contrast to the usual com- tibody for use in diagnostic and therapeutic proce- plement of sex chromosomes, one X and one Y (XY), dures (monoclinal antibodies). Klinefelter males usually have two X’s and one Y Mendelian-–referring to a trait that is controlled by (XXY), although some have multiple Y’s or more than a single gene, and which therefore shows a simple two X’s. Clinical symptoms are abnormal height, pattern of inheritance (dominant or recessive). So 88 . Human Gene Therapy—Background Paper

named because traits of this sort were first recog- Mutagen--any substance that can cause changes in nized by Gregor Mendel, the Austrian monk whose the structure of hereditary nucleic acids (DNA, RNA) early researches laid the basis for modern genetics. or the way the information they contain is trans- Messenger RNA (mRNA)—a ribonucleic acid mole- mitted to offspring. cule produced by transcribing a nucleotide base se- Myopia (nearsightedness)--a defect in vision such quence from DNA into a complementary sequence that objects can be accurately resolved only when of RNA. Messenger RNA molecules carry the in- they are unusually close to the eyes. An autosomal structions for assembling enzymes (protein mole- dominant form is known, but many (perhaps most) cules) from the chromosomes in the nucleus to the cases are either non-Mendelian or complex in their synthetic apparatus (ribosomes) in the cytoplasm, mode of inheritance (i.e., polygenic, or involving or cellular tissue outside the nucleus. variable expressivity or incomplete penetrance). Metachromatic leukodystrophy (MLD)—several Neural tube defect-the neural tube is formed by the closely related disorders characterized by a degen- fusion of the neural folds, which are ridges of tissue eration of the protective sheath surrounding nerve that arise on either side of the primitive streak. The cells (myelin) and an accumulation of certain meta- brain and spinal cord develop from the neural tube, bolic compounds as a result of insufficient activity and neural tube defects are any that affect their for- of the enzyme aryl sulfatase. Death is the result of mation or development. Most such defects are de- progressive central nervous system degeneration ac- velopmental in origin; that is, though genetic fac- companied by abnormalities of the peripheral tors may be involved these defects are more likely nerves, kidney, and liver. to be polygenic or complex rather than single gene, Metallothionein—a protein that binds metal ions. Mendelian traits. The promoter sequence that controls the produc- Oligonucleotide–nucleic acid molecules formed by tion of metallothionein has been spliced to other the joining of a small number of nucleotide bases genes and used to control their expression after (generally fewer than 10 or 20). A short sequence gene transfer, as in, for example, the rat growth of DNA or RNA. hormone transplanted into mice, resulting in Oncogene--a gene of which one or more mutant “mighty” mice of larger than normal size. forms is associated with cancer formation. Microinjection—the technique of introducing very Ornithine carbamoyl transferase deficiency— small amounts of material (DNA or RNA molecules; (transcarbamylase deficiency)–an X-linked defect enzymes; cytotoxic agents) into an intact cell associated with a specific enzyme deficiency in the through a microscopic needle penetrating the cell nitrogen cycle (transcarbamylase). Symptoms in- membrane. clude chronic ammonia intoxication, mental deteri- Morula—the solid mass of cells resembling a mul- oration, and liver failure. berry (“morula” in Latin) formed by the cleavage of Papilloma virus (Shope)—a DNA virus found in rab- a zygote; the stage before blastocyst. bits that is associated with elevated arginase activ- Mucopolysaccharidoses--a group of heritable dis- ity levels in epithelial cells. (See argininemia). eases marked by defects in the metabolism of a class Penetrance--refers to the frequency with which the of molecule, the glycosaminoglycans (formerly effects of a gene (whether dominant or recessive) called mucopolysaccharides). Symptoms usually in- known to be present are seen in the individuals car- clude mental retardation (usually severe) and rying it. various skeletal abnormalities all accompanied by Peptide—a class of compounds formed by joining abnormal deposition of mucopolysaccharides in amino acids together by a chemical process that pro- tissues or excretion in urine. duces one molecule of water for each joining of one Muscular dystrophy (Duchenne type)—an X-linked amino acid to another. Peptides are intermediate in recessive defect (therefore most affected individuals size between amino acids and proteins. are male) of muscle metabolism that usually causes Phage–see “bacteriophage.” death by the age of twenty. Phenylketonuria (PKU)—an inborn error of metab- Multigenic disorder—(polygenic disorder)—a genetic olism, or genetic disease, caused by the inability to defect resulting from the interaction of alleles of metabolize phenylalanine to tyrosine. The resulting more than one gene. Although such disorders are accumulation of phenylalanine and derived prod- heritable they depend on the simultaneous presence ucts causes mental retardation. The disease is due of several alleles and therefore the hereditary pat- to a defective enzyme (phenylalanine hydroxylase), terns are usually much more complicated than for and the symptoms can be treated and the condition simple, single-gene (Mendelian) traits, making ameliorated with a diet that eliminates phenylala- prediction and diagnosis much more difficult. nine. The disease can be diagnosed at birth by a sim- App. E—List of Abbreviations and Glossary 89

ple test that detects the characteristic elevated levels linked traits generally act as if they were recessive of phenylpyruvic acid (a phenylalanine derivative) in females and dominant in males. in the urine. Recombinant DNA (rDNA)—referring to DNA mole- Plasmid—a circular piece of DNA found in the cules that have been assembled with the use of re- cytoplasm, outside the nucleus. Replication and striction enzymes, usually (but not always) by splic- segregation of plasmids to daughter cells is inde- ing together fragments from different species. pendent of the chromosomes, and plasmid transmis- Restriction enzyme—an enzyme that has the ability sion from parent to offspring is almost exclusively to recognize a specific nucleotide sequence in a nu- matrilineal (from mother to offspring), because cleic acid (ranging from four to twelve base pairs while plasmids are common in ova they are gener- in length) and cut, or cleave, the nucleic acid at the ally absent from that portion of the sperm that fuses point. So called because, occurring naturally in bac- with the ovum to form a zygote. teria, they recognize foreign nucleic acid (e.g. the PNP deficiency—an autosomal recessive disorder of DNA of a bacterial virus as it begins to infect and immunity caused by deficiency of the enzyme destroy its host) and destroy it, thus restricting the purine nucleoside phosphorylase. ability of the virus to prey upon certain potential Polycystic kidney disease—a hereditary disease host strains. Over four hundred different restriction (single gene dominant) in which a progressive enzymes are known, recognizing a great variety of deterioration of kidney function is associated with different nucleotide base sequences. This has made the development of large numbers of cysts. possible the cutting and splicing together of nucleic Polygenic—referring to a trait or characteristic that acid within and between different organisms and is controlled not by one gene but rather by. two or species. more acting in concert. Ribosome—a cellular organelle which is the site of Polymerization—the process of joining molecular messenger RNA translation, the process of reading subunits (e.g., nucleotide base pairs) together in se- the instructions in an mRNA molecule and using quence to form a larger molecule (e.g., a polynu- them as the guide to constructing the specified pro- cleotide). primitive streak—the first visible sign of tein. Ribosomes are composed of both RNA and pro- differentiation in the developing embryo. It is a tein, and they spontaneously assemble from the nec- darkened longitudinal stripe that forms at the essary constituents present in the cell. caudal (tailward) end of the embryo, and is com- RNA (Ribonucleic acid)—a polynucleotide consist- posed of a layer of ectodermal cells (which develop ing of a backbone of alternating phosphate and into skin and nervous tissue) and it marks the future sugar (ribose) molecules to which are attached the location of the longitudinal exis of the embryo. nucleotide bases adenine (A), thymine (T), guanine probes—molecules that make it possible to seek out (G) and uracil (U, which replaces the cytosine, C, of and identify specific cellular features (see DNA DNA). There are several classes of RNA that serve probes). different purposes, including messenger RNA (mRNA), Promoter—a region of a DNA molecule found in transfer RNA (tRNA), and ribosomal RNA (rRNA). (See front of a gene (as the DNA molecule is “read” by Technical Notes. ) the proper enzymes) that controls the expression Sickle cell disease (anemia)—a hereditary hemo- of the gene. globinopathy caused by the presence of a defective Protoplasm (first formed)—a single cell or a mass of beta hemoglobin chain. Patients with sickle cell dis- protoplasm (the substance of which cells are ease have red blood cells that tend to deform into formed). The term usually refers to a bacterial cell a sickle-like shape when the abnormal hemoglobin or to an individual plant cell from which the cell crystallizes. The specific defect is caused by an ab- wall has been removed preparatory to cell-fusion normal gene resulting in the replacement of the experiments. usual amino acid, glutamic acid, with valine, in the Pyridoxine responsive hemocystinuria—a condi- sixth amino acid position in the beta-hemoglobin tion of excess cystine in the blood that can be molecule. This alters the resulting beta globin mol- treated with the drug pyridoxine. ecule in such a way as to increase its propensity to Recessive—(contrast with Dominant) referring to an crystallize, thus rupturing the red blood cell and allele of a gene that will not be seen in the pheno- causing the cells to lodge in small blood vessels. type of the organism carrying it unless it is present Sickle cell trait—refers to a person who is hetero- in two copies (i.e., on both chromosomes), or homozygous for the gene producing the abnormal form zygous. If present in only one copy, or heterozy- of the beta hemoglobin chain. People carrying the gous, its presence will be masked. (See Carrier). X- sickle cell gene in heterozygous form (carriers) are

38-803 0 - 84 - 7 : QL 3 —

90 • Human Gene Therapy—Background Paper

usually asymptomatic, and thus not afflicted by the cellular environment to ribosomes that are trans- disease. Under some conditions of extreme exertion lating mRNA into proteins (constructing proteins that reduce the concentration of oxygen in the blood according to the information encoded in the parent a small amount of sickling of red blood cells may DNA template from which the mRNA was copied). be detected, but usually not enough to bring on any Translation—the process of decoding the informa- of the pathological conditions of the disease. The tion in an mRNA molecule and using it to direct the mutation is found with high frequency in some pop- construction of protein molecules specified in the ulations subject to malarial infections, such as Afri- messenger RNA. can blacks. The defective gene is thought to be main- Transposable elements—a class of DNA molecules tained in the population because it confers increased capable of insertion into the chromosomes of the resistance to malaria upon heterozygotes. host organism at any or several of numerous posi- Single gene disorder (Mendelian disorder)--a ge- tions, and of moving from one position to another. netic disease caused by a single gene that shows a Speculation on the origin of these molecules sug- simple pattern of inheritance (e.g., dominant or gests that they may be derived from virus-like recessive, autosomal, or X-linked). ancestors. They have been called “parasitic” DNA. Somatic—referring to body tissues apart from repro- Ultrasound—high frequency sound waves that can ductive (germinal) tissues. be focused and used to picture tissues, organs, struc- Tay-Sachs disease—an autosomal recessive genetic tures, or tumors within the body. Ultrasound is par- defect resulting in developmental retardation, paral- ticularly useful for in utero examinations of the ysis, dementia, and blindness followed by death, fetus. It is often used to locate the fetus and the usually before the end of the third year of life. The placenta prior to such procedures as amniocentesis defective gene codes for hexosaminidase A, an en- or chorionic villus biopsy. zyme that degrades certain chemicals in the brain. Urea-cycle defects—the urea cycle is the metabolic Symptoms are caused by an accumulation of cere- pathway in the body that moves nitrogen from one bral gangliosides, fatty acid, and sugar molecules source to another, and takes it out of and puts it found in the brain and nervous tissue. The gene is into the body chemistry when and where needed. found in highest frequency among Ashkenazic Jews Each different step is mediated by one or more en- of Eastern European origin. zymes, all of which are genetically controlled and Tetramer--a complex molecule consisting of four ma- which can, under the influence of abnormal genes, jor portions (moieties) joined together in some re- lead to different genetic diseases (inborn errors of versible, non-structural manner (e.g., hemoglobin, metabolism) that are collectively known as urea- in which two alpha chains and two beta chains are cycle defects. joined by electromagnetic attractions). Wernicke-Korsakoff encephalopathy—a genetic Thalassemia--any of several heritable hemoglobin- disease (probably autosomal recessive) of oxalate opathies resulting from defective genes causing metabolism caused by a defective transketolase en- deletions or other alterations of different hemoglo- zyme. It seems to become clinically important only bin molecules. when the diet is deficient in thiamine, can be ex- Transcription—the process by which a complemen- acerbated by alcohol and treated with vitamin B 1 tary messenger RNA (mRNA) molecule is formed supplements. from a single stranded DNA template. The result Wilson disease--an autosomal recessive disease of of the process is that the information contained in copper metabolism in which various abnormalities DNA is transferred to mRNA which is then used as of the liver are accompanied by different neurolog- a template to direct the construction of protein ical symptoms. molecules that function in cellular metabolism. X-linked—referring to traits found on the X chromo- Transferrin—a protein molecule that carries iron in some. X-linked recessive traits are seen far more blood plasma. A number of different, genetically often in males, who have only one X chromosome, coded molecules are known. than in females, who have two. tRNA (transfer RNA)--specialized RNA molecules Zygote—a fertilised egg; a product of the fusion of that function to bring specific amino acids from the sperm and egg. Appendix F References

1. Abram, M. B., and Wolf, S. M., “Public Involve- tion, and Surrogate Motherhood (New York: St. ment in Medical Ethics: A Model for Government Martins Press, 1984c). Action,” New England Journal of Medicine 14. Andrews, L. B., “Informed Consent Statutes and 310:627-632, 1984. the Decisionmaking Process, ” Journal of Legal 2. Abramowitz, S., “A Stalemate on Test-Tube Baby Medicine 5:163-217, 1984a. Research,” The Hastings Center Report, February 15. Andrews, L. B., “The Stork Market: The Law of 1984, pp. 5-9. the New Reproduction Technologies, ” American 3. Adamson, J. W., “Hemoglobin-From F to A and Bar Association JournaJ 70:50-56, 1984b. Back)” New England Journal of Medicine 310:917- 16. Andrews, L., American Bar Foundation, personal 918, 1984. communication, Nov. 15, 1984d. 4. Advisory Subgroup on Human Reproduction, 17. Annas, G. J., “Surrogate Embryo Transfer: the European Medical Research Councils, European Perils of Patenting,” Hastings Center Report, June Science Foundation, “Human In Vitro Fertilization 1984, pp. 25, 26. and Embryo Transfer, ” Recommendations to the 18. Antonarakis, S. E., Phillips, J. A., Kazazian, H. M., European Medical Councils, Lancet Nov. 19, 1983, et al., “Genetic Diseases: Diagnosis by Restriction p. 1187. Endonuclease Analysis, ” Journal of Pediatrics 5. Alter, B. P., “Prenatal Diagnosis of Hemoglo- 100(6):845-856, 1982. binopathies: a Status Report, ’’bncet 2:1152-1155, 19. Appelbaum, P. S., and Roth, L. H., “Treatment Re- 1981. fusal in Medical Hospitals,” Making Health Care 6. Alter, B. P., “Prenatal Diagnosis of Hemoglo- Decisions: The Ethical and Legal Implications of binopathies and Other Hematologic Diseases, ” Informed Consent in the Patient-Practitioner Rela- Journal of Pediatrics 95:501, 1979. tionship, vol. II, President’s Commission for the 7. Alter, B. P., Modell, C. B., Fairweather, D., et al., Study of Ethical Problems in Medicine and Bio- “Prenatal Diagnosis of Hemoglobinopathies: a Re- medical and Behavioral Research (Washington, view of 15 Cases)” New England Journal of Medi- DC: U.S. Government Printing Office), pp. 411- cine 295:1437-1443, 1976. 477, esp. 411, 469, October 1982. 8. American Council of Life Insurance, “Bioengineer- 20. Axel, R., Testimony at a Hearing before the Sub- ing: the Promises and the Problems, ” Trend Anal- committee on Investigations and-Oversight, of the ysis Program, January 1984. Committee on Science and Technology, U.S. 9. Anderson, W. F., Testimony at a Hearing before House of Representatives, Nov. 16-18, 1982. Re- the Subcommittee on Investigations and Over- printed in Human Genetic En#”neering, U.S. Gov- sight, of the Committee on Science and Technol- ernment Printing Office, Committee Print No. ogy, U.S. House of Representatives, Nov. 16-18, 170, 1983, pp. 193-207. 1982. Reprinted in Human Genetic Engineering, 21 Baltimore, D., “Limiting Science: A Biologist’s U.S. Government Printing Office, Committee Perspective, ” Daedalus, spring 1978, pp. 37-48. Print No. 170, 1983, pp. 285-292. 22. Baskin, F. F., “Confidential Medical Records: 10. Anderson, W. F., Transcript of a presentation at Insurers and the Threat to Informational Pri- Public Forum on Gene Therapy sponsored by the vacy, ” Insurance Law Journal 669:590-610, Oc- National Institute on Child Health and Human De- tober 1978. velopment, Masur Auditorium, National Institutes 23. Baskin, Y., “Doctoring the Genes,” Science 84, De- of Health, Bethesda, MD, Nov. 21, 1983, pp. 12-30. cember 1984, pp. 52-60. 11 Anderson, W. F,, “Prospects for Human Gene 24. Baxter, J. D., and Eberhardt, N. L., “The Future Therapy,” Science 226:401-409, 1984. for Recombinant DNA in Medicine: Potential for 12 Anderson, W. F., and Fletcher, J. C., “Gene Ther- Treating Genetic Diseases, ” Triangle 21:107-110, apy in Human Beings: When Is It Ethical to Be- 1982. gin?” New England Journal of Medicine 303:1293- 25. Bayles, M. D., Reproductive Ethics (Englewood 1297, 1980. Cliffs, NJ: Prentice-Hall, 1984). 13 Andrews, L. B., New Conceptions: A Consumerk 26. Bazelon, D. L., “Governing Technology: Values, Guide to the Newest Infertility Treatments, In- Choices, and Scientific Progress, ” Technology in cluding In Vitro Fertilization, Artificial Insemina - Society 5:15-25, 1983.

91 92 . Human Gene Therapy—Background Paper

27. Beaudet, A. L., “Bibliography of Cloned Human apy Workshop, Office of Technology Assessment, and Other Selected DNAs, ” manuscript, Molecu- Sept. 25, 1984. lar Genetics Workshop, American Society of 41. Brash, J., “Mid-Trimester Termination of Preg- Human Genetics, 1983. nancy, ” Towards the Prevention of Fetal Malfor- 28. Beckwith, J., Testimony at a Hearing before the mation, J. B. Scrimgeur (cd.) (Edinburgh, Scotland: Subcommittee on Investigations and Oversight of Edinburgh University Press, 1978), pp. 177-193. the Committee on Science and Technology, U.S. 42. Breitner, J. C. S., and Folstein, M. F., “Familial Alz- House of Representatives, Nov. 16-18, 1982. Re- heimer Dementia: A Prevalent Disorder With Spe- printed in Human Genetic Engineering, U.S. Gov- cific Clinical Features, ” Psychological Medicine ernment Printing Office, Committee Print No. 14:63-80, 1984. 170, 1983, pp. 427-433. 43. Brennand, J., Chinault, A. C., Konecki, D. S., et 29. Beckwith, J., “Social and Ethical Aspects of the al., Proceedings of the National Academy of Sci- New Genetics, ” 16th Miami Symposium Advances ences, U.S.A. 79:1950-1954, 1982. in Gene Technology: Human Genetic Disorders, 44. Brinster, R. L., Richie, K. A., Hammer, R. E., et Jan. 20, 1984. al., “Expression of a Microinjected Immuno- 30. Benveniste, R., and Todaro, G. J., “Gene Trans- globulin Gene in the Spleen of Transgenic Mice, ” fer Between Eukaryotes” (Letter to the Editor), Nature 306:332-336, 1983. Science 217:1202, 1982. 45. Brotman, H., “Human Embryo Transplants, ” New 31. Benz, E. J., Forget, B. G., Hillman, D. G., et al., York Times Magazine, June 8, 1983. “Variability in the Amount of Beta-Globin mRNA 46. Budiansky, S., “Gene Therapy: Quick Fixes Not On in Beta O–Thalassemia,” Celf 14:299-312, 1978. the Cards, ” Nature 306:414, 1983. 32. Bishop, J, E., ‘(New Gene Probes May Permit Early 47. Bunn, H. F., “Disorders of Hemoglobin Structure, Predictions of Disease,” Wall Street Journal. Dec. Function, and Synthesis, ” Principles of Internal 23, 1983, vol. 107, sec. 2, p. 11. Medicine, K. J. Isselbacher, R. D. Adams, 33. Blattner, F. R., “Biological Frontiers, ” Science E. Braunwald, R. G. Petersdorf, and J. D. Wilson 222:719-720, 1983. (eds.) (New York: McGraw-Hill, 1980). 34. Boehm, C. D., Antonarakis, S. E., Phillips, J. A,, 48. Business Znsurance, “Lifespan Not Matter of Sex, ” et al., ‘(Prenatal Diagnosis Using DNA Polymor- Jan. 5, 1981. phisms: Report on 95 Pregnancies at Risk for 49. Capecchi, M. R., “High Efficiency Transformation Sickle-Cell Disease or Beta-Thalassemia, ” il’ew by Direct Microinjection of DNA Into Cultured England Journal of Medicine 308:1054-1058, Mammalian Cells)” Cell 22:479-488, 1980. 1983. 50. Capron, A. M., Testimony at a Hearing before the 35. Bookchin, R. M., Balazs, T., and Landau, L. C., Subcommittee on Investigations and Oversight of “Determinants of Red Cell Sickling: Effects of the Committee on Science and Technology, U.S. Varying pH and of Intracellular Hemoglobin Con- House of Representatives, Nov. 16-18, 1982. centration by Osmotic Shrinkage,” Journal of Lab- Printed as Human Genetic En@”neering, U.S. Gov- oratory and Clinical Medicine 87:597-616, 1976. ernment Printing Office, Committee Print No. 36. Borgaonkar, D. S. (cd.), Chromosomal Variation 170, 1983, pp. 149-190. in Man: A Catalog of Chromosomal Variants and 51. Capron, A., “Social and Ethical Aspects of the New Anomalies (New York: Alan R. Liss, 1980). Genetics,” 16th Miami Symposium Advances in 37. Botstein, D., “Mapping the Human Genome: A Gene Technology: Human Geneti”c Disorders, Jan. New Basis for Diagnosis and Treatment?” Address 20, 1984 (1984a). to Genetics and The Law: Third National Sym- 52. Capron, A. M., “Unsplicing the Gordian Knot: posium, Apr. 2-4, 1984, Boston, MA. Legal Issues in ‘The New Genetics)’ “ Address to 38. Botstein, D., White, R. L., Skolnick, M., and Davis, Genetics and The Law: Third National Sympo- R. W., ‘(Construction of a Genetic Linkage Map sium, Apr. 2-4, 1984, Boston, MA (1984b). in Man Using Restriction Fragment Length Poly- 53. Capron, A. M., “Human Genetic Engineering, ” morphisms, ” American Journal of Human Genet- Technology in Society 6:23-35, 1984c. ics 32:314-333, 1980. 54. Capron, A., “Reflections on Issues Posed by Re- 39. Bowman, J. E., and Goldwasser, E., Sickle Cell combinant DNA Molecule Technology: III,” Ethi- Fundamentals (Chicago: University of Chicago, cal and Scientific Issues Posed buv Human Uses of 1975). Molecular Genetics, Annals of the New York 40. Bowman, J, E., comments at Human Gene Ther- Academy of Sciences, vol. 265, M. Lappe and R. App. F—References 93

S. Morison (eds. ) (New York: New York Academy ord, Oct. 5, 1984, H. 11339- 1360; comments Oct. of Sciences, 1976), pp. 71-77. 9, 1984, S. 13861-13863, H. 11670-11675. 55, Cartwright, G. E., Edwards, C. Q., Kravitz, K., et 69. Connor, B. J., Reyes, A. A., Morin, C., et al., al., “Hereditary Hemochromotosis,” New Engkmd “Detection of Sickle Cell BetaS-Globin Allele by Journal of Medicine 301:175-179, 1979. Hybridization With Synthetic Oligonucleotides, ” 56. Cartwright, G. E., Skolnick, M., Amos, D. B., et Proceedings of the National Academy of Sciences, al., “Inheritance of Hemochromatosis: Linkage to U.S.A. 80:278-282, 1983. HLA, ” Transactions of the Association of Ameri- 70. Connor, S., “Gene Probes Find Huntington’s Dis- can Phewicians 16:273-281, 1978, ease, ” New Scientist, Nov. 10, 1983, p, 399. 57. Caskey, C. T., Transcript of a presentation at Pub- 71. Cook, R. H., Schneck, S. A., and Clark, D. B., lic Forum on Gene Therapy sponsored by the Na- “Twins With Alzheimer’s Disease)” Archives of tional Institute on Child Health and Human De- Neurology 38:300-301, 1981. velopment, Masur Auditorium, National Institutes 72. Cook, R. H., Ward, B., and Austin, J. H., “Studies of Health, Bethesda, MD, Nov. 21, 1983, pp. 58-79. in Aging of the Brain, IV. Familial Alzheimer Dis- 58. Cavalieri, L. F., Testimony at a Hearing before the ease: Relation to Transmissible Dementia, Aneu- Subcommittee on Investigations and Oversight of ploidy, and Microtubular Defects,” Neuro]ogv the Committee on Science and Technology, U.S. 29:1402-1412, 1979. House of Representatives, Nov. 16-18, 1982. Re- 73. Cooke, R., “Sanctioned Gene Transplant in Hu- printed in Human Genetic Engineering, U.S. Gov- mans Near, ” Boston Globe, May 4, 1984, pp. 1, 8. ernment Printing Office, Committee Print No. 74. Cummins, J. D., Smith, B. D., Vance, R. N., et al., 170, 1983, pp. 470-476. Risk Classification in Life Insurance (Boston, MS: 59. Cave, L. J., “Linking Diseases to Their Genes, ” Kluwer-Nijhoff Publishing, 1983). Bioscience 34:410-412, 1984. 75. Dadone, M. M., Kushner, J. P., Edwards, C. Q., 60. Chang, J. C., and Kan, Y. W., “A Sensitive New et al., “Hereditary Hemochromatosis, ” American Prenatal Test for Sickle-Cell Anemia,” New Eng- Journal of Clinical Pathology 78:196-207, 1982. land Journal of Medicine 307:30-32, 1982. 76. Davis, B., “Novel Pressures on the Advance of 61. Chang, J. C., and Kan, Y. W., “Antenatal Diagno- Science, ” Ethical and Scientific Issues Posed by sis of Sickle Cell Anaemia by Direct Analysis of Human Uses of Molecular Genetics, Annals of the the Sickle Mutation, ” Lancet, Nov. 21, 1981, pp. Nefir York Academy of Sciences, vol. 265, M. 1127-1129. Lappe and R. S, Morison (eds.) (New York: New 62. Chapman, F. S., “Going for Gold in the Baby Busi- York Academy of Sciences, 1976), pp. 193-202. ness, ” Fortune, Sept. 17, 1984, pp. 41-47. 77. Davis, B., Testimony at a Hearing before the Sub- 63. Clegg, J. B., Weatherall, D. J,, and Milner, P. F., committee on Investigations and Oversight of the “Hemoglobin Constant Spring—A Chain Termina- Committee on Science and Technology, U.S. tion Mutant?” Nature 234:337-340, 1971. House of Representatives, Nov. 16-18, 1982. Re- 64. Cline, M. J., Testimony at a Hearing before the printed in Human Genetic Engineering, U.S. Gov- Subcommittee on Investigations and Oversight of ernment Printing Office, Committee Print No. the Committee on Science and Technology, U.S. 170, 1983, pp. 462-469. House of Representatives, Nov. 16-18, 1982. Re- 78. Davis, J. G., “Genetic Disease, Government, and printed in Human Genetic Engineering, U.S. Gov- Social Justice,” Address to Genetics and The La}~J: ernment Printing Office, Committee Print No. Third National Symposium, Apr. 2-4, 1984, Bos- 170, 1983, pp. 442-461 (1982a). ton, MA. 65. Cline, M. J., “Genetic Engineering of Mammalian 79. Dean, J., and Schecter, A. N., ‘(Sickle-cell Anemia: Cells: Its Potential Application to Genetic Diseases Molecular and Cellular Bases of Therapeutic Ap- of Man, ” Journal of Laboratory and Clinical Medi- preaches, ” New England Journal of Medicine cine 99:299-308, 1982b. 299:752-763, 1978. 66. Code of Federal Regulations, Title 45, Part 46, 80. Department of Obstetrics and Gynecology, An- Mar. 8, 1983. shan, “Fetal Sex Prediction by Sex Chromatin of 67. Committee of Inquiry into Human Fertilization Chorionic Villi Cells During Early Pregnancy, ” and Embryology, Department of Health and So- Chinese Medical Journal 1:117-126, 1975. cial Security, Report of the Committee of Inquiry 81. Desnick, R. J., “Treatment of Inherited Metabolic Into Human Fertilisation and Embryology (Lon- Diseases: Current Status and Prospects, ” Genet- don: Her Majesty’s Stationery Office, July 1984). ic Disease: Diagnosis and Treatment: Proceedings 68. Conference Report on S. 540, Congressional Rec- of the Fifth Arnold O. Beckman Conference in

38-803 0 - 84 - 8 : QL 3 94 . Human Gene Therapy—Background Paper

Clinical Chemistry, A. A. C. Dietz and V. A. Mar- 95. Esber, E., comments at Workshop on Human cum (eds. ) (Monterey, CA: American Association Gene Therapy, Office of Technology Assessment, of Clinical Chemistry, 1981). U.S. Congress, Sept. 25, 1984. 82. Dorfman, P., “The Rifkin Resolution: Less Than 96. Faden, R., Chwalow, A. J., Hohzman, N. A., and Meets the Eye)” Genetic Engineering News, Horn, S. D., “A Survey to Evaluate Parental Con- July/August 1983, pp. 4, 12. sent as Public Policy for Neonatal Screening, ” 83. Dover, G. J., Charache, S. H., Boyer, C., et al., “5- American Journal of Public Health 72:1347-1352, Azacytidine Increases Fetal Hemogobin Produc- 1982. tion in a Patient With Sickle Cell Disease,” Globin 97. Finamore, E. P., “Jefferson v. Griffin Spaulding Gene Expression and Hematopoietic Differentia- Count-y Hospital Authority: Court-Ordered Sur- tion (New York: Alan R. Liss, 1983), pp. 475-488. gery to Protect the Life of an Unborn Child,” 84. Dover, G., Johns Hopkins University Hospital, per- American Journal of La w and Medicine 9:83-101, sonal communication, Mar. 5, 1984. 1983. 85. Duster, T., Testimony at a Hearing before the 98. Fletcher, J., Transcript of a presentation at Pub- Subcommittee on Investigations and Oversight of lic Forum on Gene Therapy sponsored by the Na- the Committee on Science and Technology, U.S. tional Institute on Child Health and Human De- House of Representatives, Nov. 16-18, 1982. Re- velopment, Masur Auditorium, National Institutes printed in Human Genetic Engineering, U.S. Gov- of Health, Bethesda, MD, Nov. 21, 1983a, pp. ernment Printing Office, Committee Print No. 44-58. 170, 1983, pp. 476-499. 99. Fletcher, J. C., “Moral Problems and Ethical Issues 86. Editorial, “Molecular Genetics for the Clinician, ” in Prospective Human Gene Therapy, ” Virginia Lancet 1:257-259, Feb. 4, 1984. Law Review 69:515-546, 1983b. 87. Editorial, “Gene Therapy: How Ripe the Time?” 100. Fletcher, J. C., Testimony at a Hearing before the Lancet 1:196-197, 1981. Subcommittee on Investigations and Oversight of 88. Edwards, C. Q., Cartwright, G. E., Skolnick, M. the Committee on Science and Technology, U.S. H., and Amos, D. B., “Genetic Mapping of the House of Representatives, Nov. 16-18, 1982. Re- Hemochromatosis Locus on Chromosome Six, ” printed in Human Genetic Engineering, U.S. Gov- Human Immunology 1:19-22, 1980. ernment Printing Office, Committee Print No. 89. Edwards, R, G., and Steptoe, P. C., “Current Status 170, 1983, pp. 342-386. of in vitro Fertilisation and Implantation of 101. Fletcher, J. C., “Ethics and Trends in Applied Human Embryos, ” Lancet 2:1265-1269, Dec. 3, Human Genetics, ” Birth Defects: Original Article 1983. Series 19:143-158, 1983c. 90. Embury, S. H., Lebo, R. V., Dozy, A. M., and Kan, 102. Folstein, M. F., and Breitner, J. C. S., “Language Y. W., “Organization of the Alpha-Globin Gene in Disorder Predicts Familial Alzheimer’s Disease, ” the Chinese Alpha-Thalassemia Syndromes,” Jour- Johns Hopkins Medical Journal 149:145-147, nal of C]inica] Investigation 63:1307-1310, 1979. 1981. 91. Embury, S. H., Miller, J. A., Dozy, A. M., et al., 103. Fost, N. C., “What Limits to Genetic Technology?: “Two Different Molecular Organizations Account Values in Conflict,” Address to Genetics and The for the Single Alpha-Globin Gene of the Alpha- Law: Third National Symposium, Apr. 2-4, 1984, Thalassemia-2 Genotype,” Journal of Clinical in- Boston, MA. vestigation 66:1319-1325, 1980. 104. Foundation on Economic Trends, “The Theolog- 92. Endler, J. A., Geographic Variation, Speciation, ical Letter Concerning the Moral Arguments and Clines, (Princeton, NJ: Princeton University Against Genetic Engineering of the Human Germ- Press, 1977). line Cells,” reprinted in Taking Sides: Clashing 93. Engelhardt, H. T., Jr., “Bioethics in Pluralist So- Views on Controversial Bio-Ethical Issues, C. cieties,” Perspectives in Biology and Medicine Levine (cd.) (Guilford, CT: Dushkin Publishing, 26:64-78, 1982. 1984), pp. 276-280. 94. Epstein, C. J., Cox, D. R., Schonbert, S. A., and 105. Freytag, S. O., Beaudet, A. L., Bock, H. G. O., and Hogge, W. A., “Recent Developments in the Pre- O’Brien, W. E., “Molecular Structure of the natal Diagnosis of Genetic Diseases and Birth Human Arginosuccinate Synthetase Gene: Ocur- De fects,” Annual Review of Genetics 17:49-83, rence of Alternative mRNA Splicing, ” Molecular 1983. and Cekdar Biology 4:1978-1984, 1984. App. F—References Ž 95

106. Friedmann, T., Testimony at a Hearing before the and V. A. Marcum (eds. ) (Monterey, CA: Ameri- Subcommittee on Investigations and Oversight of can Association of Clinical Chemistry, 1981). the Committee on Science and Technology, U.S. 116. Goossens, M., Dozy, A. M., Embury, S. H., et al., House of Representatives, Nov. 16-18, 1982. Re- “Triplicated Alpha-Globin Loci in Humans, ” Pro- printed in Human Genetic En@”neering, U.S. Gov- ceedings of the National Academy of Sciences, ernment Printing Office, Committee Print No. U.S.A. 77:518-521, 1980. 170, 1983, pp. 275-284. 117. Gordon, M. P., Transcript of a presentation at 107. Friedmann, T., Gene Therapy: Fact and Fiction Public Forum on Gene Therapuy sponsored by the (Cold Spring Harbor, NY: Cold Spring Harbor Lab- National Institute on Child Health and Human De- oratory, 1983). velopment, Masur Auditorium, National Institutes 108. Friedmann, T., “Gene Therapy—Is It Inevitable or of Health, Bethesda, MD, Nov. 21, 1983, pp. 80-92. Necessary?” Genetic Disease: Diagnosis and Treat- 118. Gordon, J. W., and Ruddle, F., “Integration and ment: Proceedings of the Fifth Arnold O. Beck- Stable Germ Line Transmission of Genes Injected man Conference in Clinical Chemistry, A. A. C. into Mouse Pronuclei, ” Science 214: 1244-1246, Dietz and V. A. Marcum (eds. ) (.Monterey, CA: 1981. American Association of Clinical Chemistry, 119. Gore, A., Jr., Chairman, Subcommittee on In\resti- 1981), gations and Oversight of the Committee on Sci- 109. Friedmann, T., “The Future of Gene Therapy—a ence and Technology, U.S. House of Representa- Reevaluation,” Ethical and Scientific Issues Posed tives, in hearings Nov. 16-18, 1982, reprinted in bbV Human Uses of Molecular Genetics, Annals of Human Genetic Engineering, U.S. Government the New York Academtiv of Sciences, vol. 265, M. Printing Office, Committee Print No. 170, 1983. Lappe and R. S. Morison (eds. ) (New York: New 120. Gorovitz, S., Transcript of a presentation at Pub- York Academy of Sciences, 1976), pp. 141-150. lic Forum on Gene Therapy sponsored by the Na- 110. Friedrich, W., Vetter, U., Heymer, B., et al., “Im- tional Institute on Child Health and Human De- munoreconstitution in Severe Combined Im- velopment, Masur Auditorium, National Institutes munodeficiency After Transplantation of HLA- of Health, Bethesda, MD, Nov. 21, 1983, pp. Haploidentical, T-Cell-Depleted Bone Marrow, ” 134-149. Lancet 1:761-764, Apr. 7, 1984. 121. Gosden, J. R., Christie, S., Gosden, C. M., et al., 111. Gartland, W., Transcript of a presentation at Pub- “Rapid Fetal Sex Determination in First Trimes- lic Forum on Gene Therapy sponsored by the Na- ter Prenatal Diagnosis by Dot Hybridization of tional Institute on Child Health and Human De- DNA Probes, ” Lancet 1:540-542, Mar. 10, 1984. velopment, Masur Auditorium, National Institutes 122. Gosden, J, R., Mitchell, A. R., Gosden, C. M., et of Health, Bethesda, MD, Nov. 21, 1983, pp. al., “Direct Vision Chorion Biopsy and Chromo- 188-192. some-Specific DNA Probes for Determination of 112. Glick, J. L., “Reflections and Speculations on the Fetal Sex in First-Trimester Prenatal Diagnosis, ” Regulation of Molecular Genetic Research,” Ethi- Lancet 2:1416-1419, 1982. cal and Scientific Issues Posed by Human Uses of 123. Graf, L. H., Jr., “Gene Transformation, ” American Molecular Genetics, Annals of the New York Scientist 70:496-505, September/October 1982. Academtiv of Sciences, vol. 265, M. Lappe and R. 124. Green, H. P., and Capron, A. M., “Issues of Law Morison (eds.) (New York: New York Academy of and Public Policy in Genetic Screening, ” Ethical, Sciences, 1976), pp. 178-192. Legal, and Social Dimensions of Human Genetic 113. Goldberg, D. A., Posakony, J. W., and Maniatis, T., Screening, D. Bergsma, M. Lappe, M. O. Robbin, “Correct Developmental Expression of a Cloned et al., (eds. ) (New York: Stratton Intercontinental Alcohol Dehydrogenase Gene Transduced Into Medical Book Corp., 1974). the Drosophila Germ Line, ” Cell 34:59-73, 1983. 125. Green, H. P., “Law and Genetic Control: Public 114. Goldstein, J. L., and Brown, M. S., “Familial Hyper- Policy Questions, ” Ethical and Scientific Issues cholesterolemia, ” in The Metabolic Basis of In- Posed buy Human Uses of Molecular Genetics, An- herited Disease, J. B. Stanbury, J. B. Wyngaarden, nals of the New York Academy of Sciences, vol. D. S. Fredrickson, J. L. Goldstein, and M. S. Brown 265, M. Lappe and R. S. Morison (eds.) (New York: (eds.) (New York: McGraw-Hill, 1983). New York Academy of Sciences, 1976), pp. 170-175. 115. Good, R. A., “Progress in Bone Marrow Transplan- 126. Grobstein, C., Transcript of a presentation at Pub- tation, ” Genetic Disease: Diagnosis and Treat- lic Forum on Gene TherapJr sponsored by the Na- ment: Proceedings of the Fifth Arnold O. Beck- tional Institute on Child Health and Human Devel- man Conference in Clinical Chem”stry, A. C. Dietz opment, Masur Auditorium, National Institutes of 96 Ž Human Gene Therapy—Background Paper

Health, Bethesda, MD, Nov. 21, 1983, pp. 118-122 140. Hobbins, J. C., Venus, I., and Mahoney, M. J., and 207-212. “Ultrasonography and Fetoscopy in the Prenatal 127. Grobstein, C., Testimony at a Hearing before the Detection of Hereditary Disorders,” Genetic Subcommittee on Investigations and Oversight of Issues in Pediatric and Obstetric Practice, M. M. the Committee on Science and Technology, U.S. Kaback (cd.) (Chicago: Year Book Medical Pub- House of Representatives, Nov. 16-18, 1982. Re- lishers). printed in Human Genetic Engineering, U.S. Gov- 141. Hodgen, G, D., Statement before the Subcommit- ernment Printing Office, Committee Print No. tee on Investigations and Oversight of the Com- 170, 1983, pp. 512-528. mittee on Science and Technology, U.S. House of 128. Grobstein, C., and Flower, M., “Gene Therapy: Representatives, Aug. 9, 1984. Proceed With Caution,” Hastings Center Report, 142. Hodgkinson, S., and Scambler, P., “Recombinant April 1984, pp. 13-17. DNA Techniques in Diagnostic and Preventive 129. Gusella, J. F., Wexler, N. S., Conneal]y, P. M., et Medicine,” BioEssays 1:12-15, 1984. al., ‘(A Polymorphic DNA Marker Genetically 143. Hook, E. B., and Hamerton, J. L., “The Frequency Linked to Huntington’s Disease,” Nature 306:234- of Chromosome Abnormalities Detected in Con- 238, 1983. secutive Newborn Studies—Differences Between 130. Guy, R. B., Gavrilis, P. K., and Rothenberg, S. P., Studies—Results by Sex and by Severity of Pheno- “h Vitro and In Vivo Effect of Hypotonic Saline typic Involvement) ’’Population C’ogenetics: Stud- on the Sickling Phenomenon, ” American Journal ies in Humans, E. G. Hook and I. H. Porter (eds.) of Medical Science 266:267-277, 1973. (New York: Academic press, 1977). 131, Harden, B., “Of Genes and Little Boys)” The 144 Horstmann, D. M., Banatvala, J. E., Riordan, J. T,, Washingtonian, June 1984, pp. 118-123, 183-185, et al., “Maternal Rubella and the Rubella Syn- 188-189. drome in Infants,” American Journal of the Dis- 132, Harsanyi, Z., Testimony at a Hearing before the eases of Childhood 110:408-415, 1965. Subcommittee on Investigations and Oversight of 145. Horwich, A. L., Fenton, W. A., Williams, K. R., the Committee on Science and Technology, U.S. et al., “Structure and Expression of a Complemen- House of Representatives, Nov. 16-18, 1982. Re- tary DNA for the Nuclear Coded Precursor of printed in Human Genetic Engineering, U.S. Gov- Human Mitochondrial Ornithine Transcarbamy - ernment Printing Office, Committee Print No. lase,” Science 224:1068-1074, 1984. 170, 1983, pp. 221-233. 146. Housman, D., Forget, B., Skoultchi, A., and Benz, 133. Harsanyi, Z., and Hutton, R., Genetic Prophecy: E, J., “Quantitative Deficiency of Chain Specific Beyond the Double Helix (New York: Rawson, Globin Messenger Ribonucleic Acids in the Tha- Wade, 1981). lassemia Syndromes,” Pzwceedings of the National 134. Hayward, W. S., Neel, B. G., and Astrin, S. M., “Ac- Academy of Sciences, U.S.A. 70:1809-1813, 1973. tivation of Cellular Oncogenes by Promoter Inser- 147. Hug, G., Sokup, S,, Ryan, M., and Chuck, G., tion in ALV-induced Lymphoid Leukosis,” Nature “Rapid Prenatal Diagnosis of Glycogen-Storage 296:475-479, 1981. Disease Type 11 by Electron Microscopy of Uncul- 135. Health Insurance Association of America, Wash- tured Amniotic-Fluid Cells, ” New England Jour- ington, DC, personal communication, June 1984. nal of Medicine 310:1018-1022, 1984. 136. Hecht, F., Hecht, B. K., and Bixenman, H. A., “Cau- 148 Hull, R. T., “Philosophical Considerations in the tion about Chorionic Villus Sampling in the First Growing Potential for Human Genetic Control,” Trimester,” New EngZand Journal of Medicine Ethical and Scientific Issues Posed by Human Uses 310:1388, 1984. of Molecular Genetics, Annals of the New York 137. Heston, L. L., Mastri, A. R., Anderson, V. E., and Academy of Sciences, vol. 265, M. Lappe and R. White, J., “Dementia of the Alzheimer Type: Clin- S. Morison (eds.) (New York: New York Academy ical Genetics, Natural History, and Associated of Sciences, 1976), pp. 118-125. Conditions, ” Archives of General Psychiatry 149. Huntley, O. M., Transcript of a presentation at 38:1085-1090, 1981. Public Forum on Gene Therapy sponsored by the 138. Higgs, D. R., Old, J. M,, Pressley, L., et al., “A Novel National Institute on Child Health and Human De- Alpha Globin Gene Arrangement in Man,” Nature velopment, Masur Auditorium, National Institutes 284:632-635, 1980. of Health, Bethesda, MD, Nov. 21, 1983, pp. 139. Hirschhorn, K., “Autosomal Chromosome Aber- 158-169. rations: An Update)” Genetic Issues in Pediatric 150. International Council of Scientific Unions (ICSU) and Obstetric Practice, M. M. Kabacky (cd.) (Chi- Short Reports, Advances in Gene Technolo~: cago: Year Book Medical Publishers 1981). Human Genetic Disorders, Proceedings of the App. F—References . 97

16th Miami Winter Symposium, F. Ahmad, et al. House of Representatives, Nov. 16-18, 1982. Re- (eds.), vol. 1, ICSU Press, 1984. printed in Human Genetic Engineering, U.S. Gov- 151 Jackson, D., Testimony at a Hearing before the ernment Printing Office, Committee Print No. Subcommittee on Investigations and-Oversight of 170, 1983, pp. 239-242. the Committee on Science and Technology, U.S. 163 Kan, Y. W., “Prenatal Diagnosis of Hemoglobin House of Representatives, Nov. 16-18, 1982. Re- Disorders, ” Progress in Hematology, \ol. 10, E. printed in Human Genetic Engineering, U.S. Gov- B. Brown (cd. ) (New York: Grune and Stratton, ernment Printing Office, Committee Print No. 1977). 170, 1983, pp. 190-193. 164 Kan, Y. W., Dozy, A. M., Alter, B. P., et al., “Detec- 152. Jackson, L., Choriom”c Villus Sampling Newsletter, tion of the Sickle Gene in the Human Fetus: Po- hlov. 25, 1983. tential for Intrauterine Diagnosis of Sickle-Cell 153. Jackson, L., Choriom”c Villus Sampling Newsletter, Anemia)” New England Journal of Medicine 287; 1- prepared through the Division of Medical Genet- 5, 1972. ics, Jefferson Medical College, Philadelphia, PA 165. Kan, Y. W., Holland, J. P., Doz~~, A. M., et al., 19107; Feb. 14, Apr. 9, June 25, and Aug. 26, “Deletion of the Beta-Globin Structural Gene in 1984. Hereditary Persistence of Fetal Hemoglobin, ” 154 Jackson, L., Division of Medical Genetics, Jeffer- Nature 258:162-163, 1975b. son Medical College, personal communications, 166. Kantor, J. A., Turner, P. T., Nienhuis, A. W., et Mar. 6, 1984, and July 10, 1984. al., “Beta -t--Thalassemia: Mutations Which Af- 155. Jacobson, C. B., and Barter, R. H., “Intrauterine fect Processing of the Beta-Globin mRNA Precw- Diagnosis and Management of Genetic Defects, ” sor,” Cc]] 21:149-157, 1980. American Journal of Obstetrics and Guvnecology 167. KaZy, z., ROZOvky, 1. S., and Bakharev, J’. A., 99:796-807, 1967. ‘( Chorion Biopsy in Early Pregnancy: A Method 156 Jenks, S., “Gene Therapy Nears Reality, Stirring for Early Prenatal Diagnosis for Inherited Dis- Hope and Fear,” Washin@on Times, Mar. 27, orders, ” Prenatal Diagnosis 2:39-45, 1982. 1984, pp. 1, 12A; “Genetic Scientists Focus on 2 168. Kevles, D. J., “Annals of Eugenics: A Secular Grim Diseases, ” Washington Times, Mar. 28, Faith, ” series of four articles appearing in the The 1984, PP. 1, 5A; “Ethical Consideration Builds Ne\v Yorker, Oct. 8, 1984, pp. 51ff.; Oct. 15, 1984, Over DNA,” Washin@on Times, Mar. 29, 1984, pp. 52ff.; Oct. 22, 1984, pp. 92ff.; Oct. 29, 1984, pp. 1, 5A; “How Much Genetic Tampering Is pp. 51ff. Proper?” Washin#on Times, Mar. 30, 1984, p. 4A; 169. Kidd, t’. J., Golbus, M. S., }Vallace, R. B., et al., all articles appeared under the title Gene Splic- “Prenatal Diagnosis of Alpha l-fi.ntitrypsin Defi- ing: Cure or Curse?. ciency by Direct Analysis of the Mutation Site in 157 Johnson, J., “Human Gene Therapy, ” Congres- the Gene, ” New England Journal of Medicine sional Research Service Review 5:19-21, October 310:639-642, 1984. 1984. 170. King, P., Testimony at a Hearing before the Sub- 158. Jolly, D. J., Esty, A. C., Bernard, H. U., and Fried- committee on Investigations and Oversight of the mann, T., “Isolation of a Genomic Clone Partially Committee on Science and Technology, U.S. Encoding Human Hypoxanthine Phosphoribosyl- House of Representatives, Nov. 16-18, 1982. Re- transferase,” Proceedings of the National Acad- printed in Human Genetic Engineering, U.S. Gov- emy of Sciences, U.S.A. 79:5038-5041, 1982. ernment Printing Office, Committee Print No. 159. Judson, H. F., The Eighth Dauy of Creation (New 170, 1983, pp. 528-534. York: Touchstone, Simon & Schuster, 1980). 171. Kolata, G., ‘(Closing in on a Killer Gene, ” Disco\’er, 160. Judson, H. F., “Gene Therapy: So Close and Yet March 1984, pp. 83-87 (1984a). So Far Away, ” review of Friedmann, T., Gene 172. Kolata, G., “Globin Gene Studies Create a Puzzle,” Therapy: Fact and Fiction, in Science 84 vol. 5, Science 223:470-471, 1984b. April 1984, pp. 88, 90. 173. Kolata, G., “Gene Therapy Method Shows Prom- 161. Kacian, D. L., Gambino, R., Dow, L. W., et a],, “De- ise, ” Science 223:1376-1379, 1984c. creased Globin Messenger RNA in Thalassemia 174. Krause, R. M., Director, National Institute of Detected by Molecular Hybridization)” Pro- Allergy and Infectious Diseases, National Insti- ceedings of the National AcademLv of Sciences, tutes of Health, Department of HeaIth and Human U.S.A. 70:1886-1890, 1973. Services, “Recombinant DNA Research; Actions 162. Kan, Y. W., Testimony at a Hearing before the Under Guidelines,” Federal Register 49:17844- Subcommittee on In\7estigations and Oversight of 17848, Apr. 25, 1984. the Committee on Science and Technolog--, U.S. 175. Kravitz, K., Skolnick, M., Cannings, C., et al., 98 . Human Gene Therapy—Background Paper

“Genetic Linkage Between Hereditary Hemochro- 190. Lewontin, R. C., Rose, S., and Kamin, L. J., Not matosis and HLA, ” American Journal of Human in Our Genes: Biology, Ideology, and Human Na- Genetics 31:601-619, 1979. ture (New York: Pantheon, 1984). 176. Kredich, N. M., and Hershfield, M. S., “Immuno- 191. Ley, T. J., DeSimone, J., Anagnou, N. P., et al., deficiency Diseases Caused by Adenosine De- “5-Azacytidine Selectively Increases Gamma-Glo- maninase Deficiency and Purine Nucleoside Phos- bin Synthesis in a Patient With Beta -t--Thalas- phorylase Deficiency,” The Metabolic Basis of semia, ” fi]ew England Journal of Medicine Inherited Disease, 5th cd,, J. B. Stanbury, et al. 307:1469-1475, 1982. (eds.) (New York: McGraw-Hill, 1983). 192. Ley, T. J., DeSimone, J., Noguchi, C. T., et al., “5- 177. Kronenberg, K., “Looking at Genes,” New England Azacytidine Increases Gamma-Globin Synthesis Journal of Medicine 307:50-52, 1982. and Reduces the Proportion of Dense Cells in Pa- 178. Kurlan, R., recorder at the Mary Jennifer Selznick tients With Sickle Cell Anemia,” Blood 62:370-380, Workshop, Hereditary Disease Foundation, Roch- 1983. ester, NY, Aug. 17-18, 1983. 193. Li, C. C., ‘(Mutations and Selection,” Human 179. Lacy, E., Roberts, S., Evans, E. P., et al., ‘(A Foreign Genetics (New York: McGraw-Hill, 1961). Beta-Globin Gene in Transgenic Mice: Integration 194. Lidz, C,, Meisel, A., “Informed Consent and the at Abnormal Chromosomal Positions and Expres- Structure of Medical Care, ” Making Health Care sion in Inappropriate Tissues, ” Cell 34:343-358, Decisions: The Ethical and Legal Implications of 1983. Informed Consent in the Patient-Pra~”tioner Rela- 180. Langone, J., “Designer Drugs and pill Pumps,” Dis- tionship, vol. II, President’s Commission for the cover, January 1984, pp. 28-31. Study of Ethical Problems in Medicine and Bio- 181. Lappe, M., “Ethical Aspects of Therapy for Ge- medical and Behavioral Research (Washington, netic Diseases, ” in Genetic Disease: Diagnosis and DC: Government Printing Office, October 1982), Treatment: Proceedings of the Fifth Arnold O. pp. 317-410, esp. 399-405. Beckman Conference in Clinical Chemistry, A. A. 195. Lippman, A., “Consequences of Chorionic Biopsy,” C. Dietz, and V. A. Marcum (eds.) (Monterey, CA: New England Journal of Medicine 310:1121, 1984. American Association of Clinical Chemistry, 196. Lubin, B. H., Pena, V., Mentzer, W. C., et al., ‘(Di- 1981). methyl Adipimidate: A New Antisickling Agent, ” 182. Lappe, M., “Reflections on the Cost of Doing Proceedings of the National Academy of Sciences, Science,” Ethical and Scientific Issues Posed by U.S.A. 72:43-46, 1975. Human Uses of Molecular Genetics, Annals of the 197. Lubs, H. A., “Frequency of Genetic Disease, ” in New York Academy of Sciences, vol. 265, M. Lubs, H. A., and de la Cruz, F., Genetic Counsel- Lappe and R. S. Morison (eds.), (New York: New ing (New York: Raven, 1977), pp. 1-16. York Academy of Sciences, 1976), pp. 102-109. 198. Mahoney, M. J., “Gene Transfer Technology: State 183. Leder, P., “A New Genesis for Genetics and Medi- of the Art, ” Address to Genetics and The Law: cine, ” Lynen Lecture, 16th Miami Symposium, Third National Symposium, Apr. 2-4, 1984, Bos- Jan. 16, 1984, reprinted in BioEssays 1:27-29 and ton, MA. 52-54, 1984. 199. Maquat, L. E., “Processing of the Human Beta- 184. Leder, P., “Discontinuous Genes,” New England Globin mRNA Precursor to mRNA Is Defective in Journal of Medicine 298:1079-1081, 1978. Three Patients with Beta -t- —Thalassemia, ” Pro- 185. Leder, P., Battey, J., Lenoir, G., et al., “Transloca- ceedings of the National Academy of Sciences, tions Among Antibody Genes in Human Cancer, ” U.S.A. 77:4287-4291, 1980. Science 222:765-771, 1983. 200. Maranto, G,, “Attack on the Gene Splicers,” Dis- 186. Lejeune, J., “Le Mongolism: Premier Exampie cover, August 1984, pp. 19-25 (1984a). D’Aberration Autosomique Humaine, ” Ann. 201. Maranto, G., “Clones on the Range, ” Discover, Genet. Sem. Hop. Paris, 1:41-49, 1959. August 1984, pp. 34-38 (1984b). 187. Lenon, J. L., “The Fetus as a Patient: Emerging 202. Marbach, W. D., “New Wave of Computer Crime,” Rights as a Person?” American Journal of Law and Newsweek, 102:45, 1983. Medicine 9:1-29, 1983. 203. Marx, J. L., “Gene Transfer Into the Drosophila 188. Lewin, R,, “No Genome Barriers to Promiscuous Germ Line,” Science 218:364-365, 1982. DNA,” Science 224:970-971, 1984. 204. Mayr, E., Animal Species and Evolution (Cam- 189. Lewontin, R. C., The Genetic Basis of Evolutionary bridge, MA: Harvard University Press, 1963). Change (New York: Columbia University Press, 205. Mayr, E., Populations, Species and Evolution 1974). (Cambridge, MA: Harvard University Press, 1970). App. F—References • 99

206. ltlcAuliffe, K., and McAuliffe, S., “Keeping Up of Health, Bethesda, MD, Nov., 1983, p. 215 With the Genetic Revolution, ” New York Times (1983a). Afagazine Nov. 6, 1983, PP. 41-44, 92-97. 221. Miller, A, D., Eckner, R. J., Jol]y, D. J., et al., “Ex- 207. McCarthy, C., Transcript of a presentation at Pub- pression of a Retrovirus Encoding Human HPRT lic Forum on Gene Therapy sponsored by the Na- in Mice, ” Science 225:630-632, 1984. tional Institute on Child Health and Human De- 222. Miller, H. I., “The Role of the Food and Drug velopment, Masur Auditorium, National Institutes Administration in the Regulation of the Products of Health, Bethesda, MD, Nov. 21, 1983, pp. of Recombinant DNA Technolo~v: Update 1983, ” 181-187. Recombinant DNA Applications to Human Dis- 208. McCormick, R. A., Testimony at a Hearing before ease: Banbury Report 14, C. T. Caskey and R. L. the Subcommittee on Investigations and Over- White (eds.) (Cold Spring Harbor, NY: Cold Spring sight of the Committee on Science and Technol- Harbor Laboratory, 1983b). oqv, U.S. House of Representatives, Nov. 16-18, 223. Miller, H. I., “Gene Therapy: Overregulation May 1982. Reprinted in Human Genetic Engineering, Be Hazardous to Our Health, ” Gene 27:1-2, 1984. U.S. Government Printing Office, Committee 224. Milunsky, A., ‘(Prenatal Genetic Diagnosis and the Print No. 170, 1983, pp. 305-311. Lawr,” Genetics and the Law II, A. Milunsky and 209. McCormick, R. A., “Bioethics in the Public Forum,” G. J. Annas (eds.) (New York: Plenum Press, 1980). itIilbank Memorial Fund Quarter&: Health and 225. Mishkin, B., Transcript of a presentation at Pub- Society 61:113-126, 1983. lic Forum on Gene Therapy sponsored by the Na- 210. McCormick, R., Kennedy Institute for Ethics, tional Institute on Child Health and Human De- Georgetown University, Washington, DC, 1984. \,elopment) ~~asur Auditorium, National Institutes 2 II. AlcDonald, K., “Gene Therapy on Humans: More of Health, Bethesda, MD, No\r. 21, 1983, pp. Tests on Animals Said Necessary, ” Chronicle of 193-207. Higher Education, Nov. 30, 1983, p. 10. 226. Morrow, J, F., “The Prospects for Gene Therapy 212. McDonald, K., “NIH Advised to Set Up Panel to in Humans,’) Ethical and Scientific Issues Posed Reviewr Plans for ‘Gene Therapy’ on Humans, ” btiv Human Uses of Molecular Genetics, Annals of The Chronicle of Higher Education, Jan. 4, 1984, the New York Academ&v of Sciences, vol. 265, hf. pp. 17-18. Lappe and R. S. Nlorison (eds. ) (New York: N’eiv 213. McGill, D., The Wharton School, Philadelphia, PA, York Academy of Sciences, 1976), pp. 13-19. personal communication, July 1984. 227. Motulsky, A. G., ‘(Impact of Genetic Manipulation 214, NlcKnight, G. S., Hammer, R. E,, Kuenzel, E. A., on Society and Medicine, ” Science 219:135-140, and Brinster, R. L., “Expression of the Chicken 1983. Transferring Gene in Transgenic Mice, ” Cell 228. Murray, J. M., Davies, K. E., Harper, P. S., et al., 34:335-341, 1983. “Linkage Relationship of a Cloned DNA Sequence 215. McKusick, V. A., A4endelian Inheritance in Man, on the Short Arm of the X Chromosome to Du- 6th ed. (Baltimore: Johns Hopkins University chenne Muscular Dystrophy, ” A’ature 300:69-71, Press, 1983). 1982. 216. Mercola, K. E., and Cline, M. J., “The Potentials 229. Murray, T. H., “Thinking the Unthinkable About of Inserting New Genetic Information,” New Eng- Genetic Screening,” Across the Board 20:34-39, land Journal of Medicine 303:1297-1300, 1980. June 1983. 217. Merz, B., “Gene Therapy: Correcting the Errors 230. Nadler, H. L., “Antenatal Detection of Hereditary in Life’s Blueprint, ” Medical World News (12519): Disorders,” Pediatrics 42:912-918, 1968. 46-62, Oct. 8, 1984. 231. National Council of Churches of Christ, U. S. A., 218. Milewski, E., “The NIH Guidelines for Research Panel on Bioethical Concerns, Genetic Engineer- Involving Recombinant DNA Molecules,” available ing: Social and Ethical Consequences (New York: through the Office of Recombinant DNA Activi- Pilgrim Press, 1984). ties, National Institute of Allergy and Infectious 232. National Institute of Child Health and Human De- Diseases, National Institutes of Health, Bethesda, velopment Study Group, National Institutes of MD 1984. Health, Public Health Service, Department of 219. Miller, J. A., “The Clergy ponder the New Genet- Health and Human Services, ‘( Midtrimester Am- ics,” Science News 125:188-190, 1984. niocentesis for Prenatal Diagnosis: Safety and Ac- 22o. Miller, H., Transcript of a presentation at Public curacy, ” Journal of the American Medical Asso- Forum on Gene Therap-v sponsored by the Na- ciation 236:1471-1476, 1976. tional Institute on Child Health and Human De- 233. National Institutes of Health, Public Health Ser\r- \,elopment, Masur Auditorium, National Institutes ice, U.S. Department of Health and Human Serv - 100 Human Gene Therapy—Background Paper

ices, NIH Data Book, 1984, NIH Publication No. duction and Testing of New Drugs and Biological 84-1261. Produced by Recombinant DNA Technolo~v, ” 234. Neale, A., Transcript of a presentation at Public draft, Nov. 7, 1983. Forum on Gene Therapy sponsored by the Na- 245. Office of Medical Application of Research, Na- tional Institute on Child Health and Human De- tional Institutes of Health, Public Health Service, velopment, Masur Auditorium, National Institutes U.S. Department of Health and Human Services, of Health, Bethesda, MD, Nov. 21, 1983, pp. Diagnostic Ultrasound Ima@”ngin Pregnanq~, vol. 122-134. 5, No. 1, 1984. 235. Nelson, J. R., “The Human Problem of Human 246. Office of Technology Assessment, U.S. Congress, Genetic Engineering,” Address to Genetics and Impacts of Applied Genetics: Microorganisms, The Law: Third National Symposium, Apr. 2-4, Plants, and Animals, U.S. Government Printing 1984, Boston, MA (1984a). Office, OTA-HR-132, April 1981. Also available as 236. Nelson, J. Robert, Boston University, personal Genetic Technology: A New Frontier (Boulder, communication, September 1984 (1984b). CO: Westview Press, 1982). 237. Neville, R., “Gene Therapy and the Ethics of 247. Office of Technology Assessment, U.S. Congress, Genetic Therapeutics, ” Ethical and Scientific The Role of Genetic Testing in the Prevention of Issues Posed btiv Human Uses of Molecular Genet- Occupational Disease, U.S. Government Printing ics, Annals of the New York Academy of Sciences, Office, OTA-BA-194, April 1983. VO1. 265, M. Lappe and R. S. Morison (eds.), (New 248. Office of Technology Assessment, U.S. Congress, York: New York Academy of Sciences, 1976), pp. Commercial Biotechnology: An International An- 153-162. a@sis, U.S. Government Printing Office, OTA-BA- 238. Newmark, P., “Medical Genetics: Molecular Diag- 218, January 1984. nostic Medicine, ” Nature 307:11-12, 1984. 249. Old, J. M., Ward, R. H. T., Karagozlu, F., et al., 239. Niazi, M., and Coleman, D. V., “Trophoblast “First-Trimester Fetal Diagnosis for Hemoglobin- Sampling in Early Pregnancy: Culture of Rapidly opathies: Three Cases, Lancet 2:1413-1416, 1982. Dividing Cells from Immature Placental Villi,” Brit- 250. Old, J., Longley, J., Wood, W. G., et al., “Molecular ish Journal of Obstetrics and Guvnaecology Basis for Acquired Hemoglobin H Disease, ” Na- 88:1081-1085, 1981. ture 269:524-525, 1977. 240. Nienhuis, A, W., Turner, P., and Benz, E. J., Jr$) 251, Orkin, S. H., “The Duplicated Human Alpha -Glo- “Relative Stability of Alpha- and Beta -Globin Mes- bin Genes Lie Close Together in Cellular DNA,” senger RNAs in Hornozygous Beta i- —Thalas- Proceedings of the National Academy of Sciences, semia, ” Proceedings of the National Academuy of U.S.A. 75:5950-5954, 1978. Sciences, U.S.A. 74:3960-3964, 1977. 252. Orkin, S. H., “Genetic Diagnosis of the Fetus, ” 241. Nigen, A. M., Njikam, N., Lee, C. K., and Manning, ~Vature 296:202-203, 1982. J. M., “Studies on the Mechanism of Action of 253. Orkin, S. H., Little, P. R. R., Kazazian, H. H., and Cyanate in Sickle Cell Disease: Oxygen Affinity Boehm, C., “Improved Detection of the Sickle and Gelling Properties of Hemoglobin S Carbamy - Mutation by DNA Analysis, ” New England Jour- lated on Specific Chains)” JournaI of Biological nal of Medicine 307:32-36, 1982. Chemistxy 249:6611-6616, 1974. 254. Orkin, S. H., Markham, A. F., and Kazazian, H. 242. Nightingale, E., Testimony at a Hearing before the H., Jr., “Direct Detection of the Common Medi- Subcommittee on Investigations and Oversight of terranean Beta-Thalassemia Gene With Synthetic the Committee on Science and Technology, U.S. DNA Probes: An Alternate Approach for Prenatal House of Representatives, Nov. 16-18, 1982. Re- Diagnosis, ” Journal of Clinical Investigation printed in Human Genetic Engineering, U.S. Gov- 71:775-779, 1983. ernment Printing Office, Committee Print No. 255. Orkin, S. H., Nathan, D. G., “The Molecular 170, 1983, pp. 500-503. Genetics of Thalassemia, ” in Advances in Human 243. Nightingale, E., ‘(Social and Ethical Aspects of the Genetics, vol. 2, Harris, H., and Hirshort, A. (eds.) New Genetics,” 16th Miami Symposium, Advances (New York: Plenum, 1981), pp. 233-288. in Gene Technology: Human Genetic Disorders, 256. Orkin, S. H., Old., J. M., Weatherall, D. J., and Jan. 20, 1984. Nathan, D. G., “Partial Deletion of Beta-Globin 244. Office of Biologics Research and Review, National DNA in Certain Patients With Beta O—Thalassemia, ” Center for Drugs and Biologics, Food and Drug Proceedings of the National Academ-v of Sciences, Administration, U.S. Department of Health and U.S.A. 76:2400-2404, 1979. Human Services, “Points to Consider in the Pro- 257. Palmiter, R. D., Brinster, R. L., Hammer, R. E., et App. F—References . 101

al., “Dramatic Growth of Mice That Develop From From an Aborted Fetus)” American Journal of the Eggs Microinjected With Metallothionein— Diseases of Childhood 110:381-389, 1965. Growth Hormone Fusion Genes)” Nature 300:611- 271. Plotkin, S. A., Farquhar, J. D., and Katz, M., “At- 615, 1982. tenuation of RA 27/3 Rubella Virus in WI-38 258. Palmiter, R. D., Norstedt, G., Gelinas, R. E., et al., Human Diploid Cells,” American Journal of the “Metallothionein—Human GH Fusion Genes Stim- Diseases of Childhood 118:178-185, 1969. ulate Growth of Mice)” Science 222:809-814, 1983. 272. Powledge, T., “Ethical Considerations in Human 259. Parkman P. D., Phillips, P. E., and Meyer, H., “Ex- Gene Transfer,” Address to Genetics and The perimental Virus Infection in Pregnant Monkey s,” Law: Third National Symposium, Apr. 2-4, 1984, American Journal of the Diseases of Childhood Boston, MA. 110:390-394, 1965. 273. President’s Commission for the Study of Ethical 260. Parkman, P. D., Meyer, H. M., Hopps, H. E., and Problems in Medicine and Biomedical and Be- Kirschstein, R. L., “Laboratory Studies with an At- havioral Research, Splicing LiYe, U.S. Government tenuated Rubella Virus,” First lnternationaZ Con- Printing Office, stock No. 83-600500, 1982. ference on Vaccines Against Viral and Rickettsial 274. President’s Commission for the Study of Ethical Diseases of Man, Pan American Health Organiza- Problems in Medicine and Biomedical and Behav- tion, report No. 147, 1966, pp. 381-389. ioral Research, Implementing Human Research 261. Parliamentary Assembly of the Council of Eur- Regulations, U.S. Government Printing Office, ope, Recommendation 934 (1982) on Genetic Engi- stock No, 83-600504, 1983a. neering, Biotechnology Law Report, January 275. President’s Commission for the Study of Ethical 1983, pp. 17-18. Problems in Medicine and Biomedical and Behav- 262. Paterson, H. E. M. H., “The Continuing Search for ioral Research, Screening and Counseling for the Unknown and Unknowable: A Critique of Genetic Conditions, U.S. Government Printing Of- Contemporary Ideas on Speciation, ” South fice, stock No. 83-600502, 1983b. African Journal of Science 77:53-57, 1981. 276. President’s Commission for the Study of Ethical 263. Pauling, L,, Itano, H. A., Singer, S. J., and Wells, Problems in Medicine and Biomedical and Behav- I. C., “Sickle Cell Anemia: A Molecular Disease,” ioral Research, Protecting Human Subjects, U.S. Science 110:543-548, 1949. Government Printing Office, stock No. 81-6001- 264. Pearson, H. A., O’Brien, R. T., and McIntosh, S., 90, 1981. “Screening for Thalassemia Trait by Electronic 277. Privacy Protection Study Commission, The Measurement of Mean Corpuscular Volume, ” Privacy Act of 1974: An Assessment, Appendix New England Journal of Medicine 288:351-353, 4, (Washington, DC: U.S. Government Printing Of- 1973. fice, 1977). 265. Pembrey, M. E., ‘(Do We Need Gene Therapy?” 278. Product News, “Chorionic Villus Biopsy, Outlook, Nature 311:200, 1984. January 1984, p. 8. 266. Perpich, J. G., “Genetic Engineering and Related 279. Quigley, M, M., and Andrews, L. B., “Human h Biotechnologies: Scientific Progress and Public Vitro Fertilization and the Law, ” Fertility and Po]icy)” Technology in Society 5:27-49, 1983. Sterility 42:348-355, 1984. 267. Phillips, J. A., III, “The Growth Hormone (hGH) 280. Quine, W. V. O., “On the Nature of Moral Values, ” Gene and Human Disease,” Recombinant DNA Ap- Theories and Things (Cambridge, MA: Harvard plications to Human Disease Banbury Report 14), University Press, 1981) C. T. Caskey and R. L. White, R. L. (eds.) (Cold 281. Raven, P. H., “Hybridization and the Nature of Spring Harbor, NY: Cold Spring Harbor Labora- Species in Higher Plants)” Canadian Botanical tory, 1983). Association Bulletin, Supplement 2, vol. 13:3-10, 268. Pirastu, M., Kan, Y. W., Cao, A., et al., “Prenatal 1980. Diagnosis of Beta-Thalassemia: Detection of a 282. Rawls, R. L., “Progress in Gene Therapy Brings Single Nucleotide Mutation in DNA,” New England Human Trials Near,” Chemical and Engineering Journal of Medicine 309:284-287, 1983. News 62(33):39-44, Aug. 13, 1984. 269. Plotkin, S. A., “Prevention of Intrauterine and 283. Recombinant DNA Advisory Committee, National Perinatal Infections, ” Clinics in Perinatology Institutes of Health, Public Health Service, Depart- 8:617-637, 1981. ment of Health and Human Services, Minutes of 270. Plotkin, S. A., Cornfeld, D., and Ingalls, T. H., Meeting, Feb. 6, 1984. “Studies of Immunization With Living Rubella 284. Recommendations of the Public Health Service Virus: Trials in Children With a Strain Cultured Advisory Committee on Immunization Practices, 102 Human Gene Therapy—Background Paper

American Journal of the Diseases of Childhood Subcommittee on Investigations and Oversight of 118:397-299, 1969. the Committee on Science and Technology, U.S. 285. Reilly, P., Genetics, Law, and Social Policy (Cam- House of Representatives, Nov. 16-18, 1982. Re- bridge, MA: Harvard University Press, 1977). printed in Human Genetic Engineering, U.S. Gov- 286. Remington, J. S., and J. O. Klein (eds.), Infectious ernment Printing Office, Committee Print No. Diseases of the Fetus and Newborn Infant, 2d ed. 170, 1983, pp. 207-220. (Philadelphia: W. B. Saunders, 1983). 301. Schecter, A., Laboratory of Chemical Biology, Na- 287. Rifkin, J., Algeny (New York: Viking, 1983). tional Institute of Arthritis, Metabolism, and Di- 288. Riskin, L. R., and Reilly, P.R. “Remedies for Im- gestive Disease, personal communication, Mar. 6, proper Disclosure by Genetic Data Banks,” Rut- 1984. gers-Camden Law Review, 1977. 302, Schmeck, H. M., “Treatment is Nearing for 289. Robertson, J. A., “Legal Issues in Human Gene Genetic Defects,” New York Times, Apr. 10, Transfers,” Address to Genetics and The Law: 1984a, pp. cl, c12. Third National Symposium, Apr. 2-4, 1984, Bos- 303. Schmeck, H. M., “New Efforts to Cure Disease by ton, MA. Gene Therapy Predicted,” New York Times, July 290. Robertson, M., “Huntington’s Disease: The Begin- 26, 1984b. ning of the End of a Dilemma?” Nature 306:222, 304. Schmitt, H., “Biotechnology and the Lawmakers, ” 1983. Technology in Society 5:5-14, 1983. 291, Rocker, 1,, and Laurence, K. M., “An Assessment 305. Schneyer, T. J., “Informed Consent and the Dan- of Fetoscopy)” Fetoscopy, I. Rocker and K. M. Lau- ger of Bias in the Formation of Medical Disclosure rence (eds. ) (Amsterdam: Elsevier/North-Holland, Practices,” Wisconsin Law Review 1976:124-170, 1981). 1976. 292. Rogers, S., “Reflections on Issues Posed by Recom- 306. Scholnick, S. B., Morgan, B. A., and Hirsh, J., “The binant DNA Molecule Technology: II,” Ethical and Cloned DOPA Decarboxylase Gene Is Develop- Scientific Issues Posed by Human Uses of Molecu- mentally Regulated When Reintegrated Into the lar Genetics, Annals of the New York Academy Drosophila Genome,” Cell 34:37-45, 1983. of Sciences, vol. 265, M. Lappe and R. S. Morison, 307. Shinn, R., Testimony at a Hearing before the Sub- (eds.) York: New York Academy of Sciences, committee on Investigations and Oversight of the 1976), pp. 66-70. Committee on Science and Technolo~, U.S. 293. Rosenberg, L. E., “New Genetics and Old Values, ” House of Representatives, Nov. 16-18, 1982. Re- The Pharos of the Alpha Omega Alpha Honor printed in Human Genetic Engz”neering, U.S. Gov- Medical Society, winter 1983, pp. 13-19. ernment Printing Office, Committee Print No. 294. Rosenberg, L. E., “Can We Cure Genetic Disease?” 170, 1983, pp. 301-305. Address to Genetics and The Law: Third National 308. Short, E. M., “Genetic Diseases,” Medical Com- Sevmposium, Apr. 2-4, 1984, Boston, MA. plications During Pregnancy, G. N, Burrow and 295. Rosenfeld, A., “At Risk for Huntington’s Disease: T. S. Ferris (eds.) (Philadelphia: W. B. Saunders, Who Should Know What and When?” The Hast- 1982), p. 109-144. ings Center Report, June 1984, pp. 5-8. 309. Shows, T. B., “The Human Molecular Map of 296. Rovner, S., “Cloning of a Gene May Bring Cure Cloned Genes and DNA Polymorphisms, ” Recom- for Rare Gaucher’s Disease,” Washin#on Post, binant DNA Applications to Human Disease, Ban- Ju]y 21, 1984, P. A2. bury Report 14, C. T. Caskey and R. L. White 297. Rowley, P. T., “Genetic Screening: Marvel or Men- (eds.) (Cold Spring Harbor, NY: Cold Spring Har- ace?” Science, 225:138-144, July 13, 1984. bor Laboratory, 1983). 298, Rubin, G. M., and Spradling, A. C,, “Genetic Trans- 310. Shulman, J., Transcript of a presentation at Pub- formation of Drosophila With Transposable E]e- lic Forum on Gene Therapy ~ponsored by the Na- ment Vectors, ” Science 218:348-353, 1982. tional Institute on Child Health and Human De- 299, Ryan, K., Transcript of a presentation at Public velopment, Masur Auditorium, National Institutes Forum on Gene Therapy sponsored by the Na- of Health, Bethesda, MD, Nov. 21, 1983, pp. 31- tional Institute on Child Health and Human De- 43. velopment, Masur Auditorium, National Institutes 311 Siegel, S., Testimony at a Hearing before the Sub- of Health, Bethesda, MD, Nov. 21, 1983, pp. 149- committee on Investigations and Oversight of the 158 171-172, and 180-181. Committee on Science and Technology, U.S. 300. Sanford, B. H., Testimony at a Hearing before the House of Representatives, Nov. 16-18, 1982. Re- App. F—References Ž 103

printed in Human Genetic Engineering, U.S. Gov- 323. Sun, M., “Martin Cline Loses Appeal on NIH ernment Printing Office, Committee Print No. Grant,” Science 218:37, 1982. 170, 1983, pp. 312-332. 324. Talbot, B., Testimony at a Hearing before the Sub- 312. Siege], S., “Genetic Engineering, ” Linacre Quar- committee on Investigations and Oversight of the ter~v, February 1983, pp. 45-55. Committee on Science and Technology, U.S. 313. Skolnick, M. H., Testimony at a Hearing before House of Representatives, Nov. 16-18, 1982. Re- the Subcommittee on Investigations and Over- printed in Human Genetic En@”neering, U.S. Gov- sight of the Committee on Science and Technol- ernment Printing Office, Committee Print No. ogy, U.S. House of Representatives, Nov. 16-18, 170, 1983, pp. 540-545. 1982. Reprinted in Human Genetic Engineering, 325. The Blue Sheet, “NIH rDNA Human Gene Ther- U.S. Government Printing Office, Committee apy ‘Points to Consider’ Draft Document Would Print No. 170, 1983, pp. 242-274. Require Investigators to Submit Information on 314. Skolnick, M. H., Willard, H. F., and Merdove, L. Side Effects and Cost,” Oct. 17, 1984, p. 4. A., “Report of the Committee on Human Gene 326. The Economist, “Science and Technology: The Mapping by Recombinant DNA Techniques, ” in Birthpangs of a New Science)” pp. 79-82; and Human Gene Mapping 7, Los Angeles Conference, “Proper Study of Mankind,” pp. 11-12, July 14, Seventh International Workshop on Human Gene 1984. Mapping, reprinted in CoVtogenetics and Cell Ge- 327. Thomas, L., “Oswald Avery and the Cascade of netics 37:210-273, 1984. Surprises,” Technology in Society 6:37-40, 1984, 315. Skew, L. C., Burkhart, B, A., and Johnson, F. M., reprinted from Esquire magazine. et al., “A Mouse Model for Beta-Thalassemia, ” Cell 328. Treisman, R., Orkin, S., and Maniatis, T., “Struc- 34:1043-1052, 1983. tural and Functional Defects in Beta -Thalassemia, ” 316, Spradling, A. C., and Rubin, G. M., “The Effect Globin Gene Expression and Hematopoietic Dif- of Chromosomal Position on the Expression of the ferentiation (New York: Alan R. Liss, Inc., 1983), Drosophila Xanthine Dehydrogenase Gene, ” C’efl pp. 99-121. 34:47-57, 1983. 329. Vaheri, A., Vesikari, T., Oker-Blum, N., et al., 317. Spradling, A., Transcript of a presentation at Pub- “Transmission of Attenuated Rubella Vaccines to lic Forum on Gene Therapy sponsored by the Na- the Human Fetus,” American Journal of the Dis- tional Institute on Child Health and Human De- eases of Childhood 118:243-246, 1969. velopment, Masur Auditorium, National Institutes 330. Van Heyningen, J’., “Cystic Fibrosis: In Search of of Health, Bethesda, MD, Nov. 21, 1983, pp. the Gene,” Nature 311:104-105, 1984. 92-104. 331. Vines, G., “Clues to Cancer From a Backwater of 318. Stanbury, J. B., Wyngaarden, J. B., Fredrickson, Science,” New Scientist, Mar. 1, 1984, pp. 10-11. D. S., Goldstein, J. L., and Brown, M. S., “Inborn 332. Vogel, F., and Motulsky, A. G., “Systematic Errors of Metabolism, ” The Metabolic Basis of In- Changes in Gene Frequencies: Mutation and herited Disease, ch. 1, 5th ed. (New York: Selection,” Human Genetics (New York: Springer- McGraw-Hill, 1983). Verlag, 1979), pp. 383-3977 and 392-403. 319. Stern, C., Principles of Human Genetics 3d ed. 333. Wade, N., “UCLA Gene Therapy Racked by (San Francisco: W. H. Freeman, 1973). Friendly Fire, ” Science 210:509-511, 1980. 320. Stich, S., Testimony at a Hearing before the Sub- 334. Wade, N., “Gene Therapy Caught in More En- committee on Investigations and Oversight of the tanglements, ” Science 212:24-25, 1981a. Committee on Science and Technology, U.S. 335. Wade, N., “Gene Therapy Pioneer Draws Mikado- House of Representatives, Nov. 16-18, 1982. Re- esque Rap, ” Science 212:1253, 1981b. printed in Human Genetic Engineering, U.S. Gov- 336. Wade, N., “Biotechnology and its Public, ” Tech- ernment Printing Office, Committee Print No. nology in Society 6:17-21, 1984. 170, 1983, pp. 534-540. 337. Wagner, T. E., Transcript of a presentation at 321. Subcommittee on Investigations and Oversight Public Forum on Gene Therapwy sponsored by the Committee on Science and Technology, U.S. National Institute on Child Health and Human De- House of Representatives, hearings on “Human velopment, Masur Auditorium, National Institutes Genetic Engineering, ” Nov. 16-18, 1982, Printed of Health, Bethesda, MD, Nov. 21, 1983, pp. by the U.S. Government Printing Office as Human 104-116. Genetic Engineering, Committee Print No 170, 338. Wagner, T. E., Hoppe, P. C., Jollick, J. D., et al., 1983. “Microinjection of a Rabbit Beta-Globin Gene Into 322. Sun, M., ‘( Cline Loses Two NIH Grants,” Science Zygotes and Its Subsequent Expression in Adult 214:1220, 1981. Mice and Their Offspring,” Proceedings of the Na - 104 . Human Gene Therapy—Background Paper

tional Acadademy of Sciences, U.S.A. 78:6376- Gene Technology: Human Genetic Disorders, Jan. 6380, 1981. 20, 1984.

339< Wallace, R. B., Schold, M., Johnson, M. J., et al., 354. Williams, D. A., Lemischka, I. R., Nathan, D. G., “Oligonucleotide-Directed Mutagenesis of the and Mulligan, R. C., ‘Introduction of New Genetic Human Beta-Globin Gene: A General Method for Material Into Pluripotent Haematopoietic Stem Producing Specific Point Mutations in Cloned Cells of the Mouse, ” Nature 310:476-480. DNA,” Nucleic Acids Research 9:3647-3656, lgsI. 355. Williamson, B., “Reintroduction of Genetically 340. Walser, M., “Urea Cycle Disorders and Other Transformed Bone Marrow Cells Into Mice, ” Hereditary Hyperammonemic Syndromes,” The Nature 284:397-398, 1980. Metabolic Basis of Inherited Disease, 5th cd., J. 356. Williamson, B., “Gene Therapy,” Nature 298:416- B. Stanbury, , et al. (eds. ) (New York: McGraw- 418, 1982. Hill, 1983). 357. Williamson, R., Eskdale, S., Coleman, D. V., et al., 341. Walters, L., “Ethical Aspects of Medical Confiden- “Direct Gene Analysis of Chorionic Villi: A Possi- tiality, ” Contemporary Issues in Bioethics, T. L. ble Technique for First-Trimester Antenatal Diag- Beauchamp, T.L., and :Walteralters, L. (eds,) (Bel- nosis of Hemoglobinopathies, ” Lancet 2: 1126- mont, CA: Wadsworth Publishing Co., 1982). 1127, NOV. 21, 1981. 342. Walters, L., Testimony at a Hearing before the 358. Williamson, R., Gilliam, C., Hodgkinson, S., et al., Subcommittee on Investigations and Oversight of “Random Gene Probes and the Mapping of Mus- the Committee on Science and Technology, U.S. cular Dystrophy and Similar Inherited Diseases, ” House of Representatives, Nov. 16-18, 1982. Re- in International Council of Scientific Unions printed in Human Genetic Engineering, U.S. Gov- (ICSU) Short Reports, Advances in Gene Technol- ernment Printing Office, Committee Print No. o~v: Human Genetic Disorders, Proceedings of 170, 1983, pp. 387-393. the 16th Miami Winter Symposium, F. Ahmad, 343. Watson, J, D., Tooze, J., and Kurtz, D. T., “Recom- et al. (eds.), vol. 1 (ICSU Press), 1984, pp. 94-99. binant DNA and Genetic Diseases, ” ch. 17 of 359. Williamson, R., St. Mary’s Hospital Medical Recombinant DNA: A Short Course (New York: School, University of London, England, personal W. H. Freeman, 1984). communication, Feb. 16, 1984. 344 Weatherall, D. J., The New Genetics and Clinical 360 Wilson, J. M., and Kelley, W. N., “Molecular Practice (London: Nuffield Provincial Hospitals Genetics of the HPRT-Deficiency Syndromes, ” Trust, 1982). Hospital Practice, May 1984, pp. 81-89, 93-95, 97, 345. Weatherall, D. J., and Clegg, J. B., The Thalas- 100. sem”a Syndromes, 3d ed. (Oxford, U. K.: Blackwell, 361 Winslow, R. M., and Anderson, W. F., “The 1981). Hemoglobinopathies, ” The Metabolic Basis of In- 346. Weatherall, D., “On the Track of Genetic Disease,” herited Disease, 5th cd., J. B. Stanbury, J. B. New Scientist, Apr. 5, 1984, pp. 32-36. Wyngaarden, D. S. Fredrickson, et al. (eds.) (New 347. Weatherall, D., “A Step Nearer Gene Therapy?” York: McGraw-Hill, 1983). Nature 310:451, 1984. 362. Wissow, L., “Diseases and Traits Relevant to 348. Weisberg, R. A., and Leder, P., “Fundamentals of Human Gene Therapy,” contract No. 433-4950.0, Molecular Genetics, ” The Metabolic Basis of In- Office of Technology Assessment, U.S. Congress, herited Disease, 5th cd., J. B. Stanbury et al. (eds.) 1984. (New York: McGraw Hill, 1983). 363. Wittgenstein, L., On Certainty (notes April 1950- 349. Weissmann, C., “The Cloning of Interferon and Aprii 1951), G. E. M. Anscornbe and G. H. von Other Mistakes)” Interferon 3 (New York: Aca- Wright, G. H. (eds.), D. Paul, and G. E. M. demic Press, 1981), pp. 101-139. Anscombe (trs.), (New York: Harper Torchbooks, 350. Wexler, N. S., Conneally, P. M., and Gusella, J. 1969). F., Huntington Disease “Discovery” Fact Sheet 364 Wolf, D. P., and Quigley, M. M., “Historical Back- (Santa Monica, CA: Hereditary Diseases Founda- ground and Essentials for a Program in In Vitro tion, May 1, 1984). Fertilization and Embryo Transfer,” Human In 351. Wexler, N. S., recorder at the Mary Jennifer Vitro Fertilization and Embryo Transfer, D. P. Selznick Mini-Workshop, Hereditary Disease Wolf and M. M. Quigley (eds.) (New York: Plenum Foundation, Bethesda, MD, Nov. 30-Dec. 1, 1983. Press, 1984), pp. 1-10. 352. White, M. M. D., Modes of Speciation (San Fran- 365, Wolstenholme, G., “Public Confidence in Scien- cisco: W. H. Freeman, 1978). tific Research: The British Response to Genetic 353. White, R., “Social and Ethical Aspects of the New Engineering,” Technology in Society 6:9-16, 1984. Genetics, ” 16th Miami Symposium Advances in 366, Woo, S. L. C., Lidsky, A. S., Guttler, F., et al., App. F—References 105

“Cloned Human Phenylalanine Hydroxylase Gene 369. k$’orld Health Organization (WHO), Working Allows Prenatal Diagnosis and Carrier Detection Group Report on the Community Control of He- of Classical Phenylketonuria, ” Nature 306: 151- reditary Anemias, in press. 155, 1983. 37o. Yang, T. P., Patel, P. I., Chinault, A. C., et al., 367. lVorking Group on Human Gene Therapy, Re- “Molecular Evidence for a New Mutation at the combinant DNA Advisory Committee (RAC), Of- hprt locus in Lesch-Nyhan Patients,” Nature fice of Recombinant DNA Activity, National Insti- 310:412-414, 1984. tute of Allergy and Infectious Diseases, National 371. Zaner, R. M., Testimony at a Hearing before the Institutes of Health, Public Health Service, U.S. Subcommittee on Investigations and Oversight of Department of Health and Human Services, open the Committee on Science and Technolo~v, U.S. meetings held Oct. 12, and Nov. 16, 1984. House of Representatives, Nov. 16-18, 1982. Re- 368. World Council of Churches, Manipulating Life: printed in Human Genetic Engineering, U.S Gov- Ethical Issues in Genetic Engineering (Geneva: ernment Printing Office, Committee Print No. Church and Society, World Council of Churches, 170, 1983, pp. 393-426. 1983).