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DOI: 10.1590/1413-812320182410.19102019 3607 A R How diseases became “genetic” TIGO A Como as doenças se tornaram “genéticas” rt ICLE Ilana Löwy (https://orcid.org/0000-0001-6963-0578) 1 Abstract This article examines the origins of the Resumo O presente artigo tem o objetivo de exa- term “genetic disease.” In the late 19 and early 20th minar as origens do termo “doença genética. No century, an earlier idea that diseases that occur in final do século XIX e início do XX, a vaga ideia families reflect a vague familiar “predisposition” que a doença manifesta entre familiares refletia was replaced by the view that such diseases have uma “predisposição” familiar, foi substituída pela specific causes, while Mendelian genetics provided visão que essas doenças possuem causas específi- then clues to the patterns of their transmission. cas, enquanto a genética mendeliana forneceu as The genetictisation of inborn pathologies took pistas para os padrões de transmissão da doença. a decisive turn with the redefinition, in 1959, of A genética das patologias congênitas deu uma Down syndrome as a chromosomal anomaly, then guinada decisiva, em 1959, com a redefinição da the development of tests for the diagnosis of other Síndrome de Down como uma anomalia cromos- hereditary pathologies. At that time, geneticists sômica e, depois, com o desenvolvimento de testes distinguished “hereditary” diseases that run in para o diagnóstico de outras patologias hereditá- families, from “genetic” conditions that are the rias. Naquela época, os geneticistas distinguiam result of new mutations during the production of doenças “hereditárias” como aquelas que acome- egg and sperm cells. In the latter case, the inborn tiam os elementos de uma família, de condições impairment is produced by an anomaly in the “genéticas” que são o resultado de novas mutações genetic material of the cell, but is not hereditary, ocorridas durante a produção dos óvulos e esper- because it is not transmitted from one or both pa- matozoides. Neste último caso, a deficiência inata rents. In the late 20th and early 21st century, new é causada por uma anomalia do material genético genomic technologies blurred the distinction be- da célula, porque não é transmitida por qualquer tween hereditary and genetic impairments, exten- um ou ambos os pais. No final do século XX e iní- ded the concept of genetic disease, and modified cio do XXI, as novas tecnologias genômicas obs- the experience of people living with such a disease. cureceram a distinção entre deficiências hereditá- 1 CERMES 3 Paris & visiting professor - Instituto Key words Heredity disease, Genetic disease, ria e a genética, estenderam o conceito da doença de Medicina Social, Down syndrome, Genomic technologies genética e modificaram a experiência das pessoas Universidade Estadual do que vivem com esse tipo de doença. Rio de Janeiro. R. Francisco Xavier 524/bl. D/7º, Palavras-chave Hereditariedade, Genética, Cro- Maracanã. mossomos, Síndrome de Down, NIPT 20550-013 Rio de Janeiro RJ Brasil. [email protected] 3608 Löwy I Hereditary diseases before genetics quired traits. Another British psychiatrist, Alfred Frank Tredgold (1870-1952) whose Textbook of An interest in traits that children inherit from Mental Deficiency, first published in 1908, then their parents – the father’s hair, the mother’s actualized and reedited until the author’s death, eyes – may be as old as civilizations, but inter- became a key source of knowledge on this ques- est in diseases that run in families is document- tion in the English-speaking world, put the ac- ed from the 17th century on, when physicians cent on the role of “pathological heredity” in pro- started to systematically record families with an ducing “feeble mindness”. Mental impairment, unusual concentration of abnormal traits1,2. The Tredgold believed, is nearly always “hereditary,” search for “morbid heredity” was intensified in a broad term which included advanced parental the 19th century. At that time, this concept in- age, alcoholism, syphilis and tuberculosis. Tred- cluded a multiplicity of causes, such as familial gold included the last two pathologies among traits (“likes begets likes”) intensified by inter- causes of hereditary “feeble mindness”, because, marriage, but also alcoholism, tuberculosis, and he argued, the geneticists’ claim that infectious venereal diseases, especially syphilis. Tubercu- diseases do not affect “germ plasm” is not plausi- losis and syphilis were classified as “hereditary ble. It is difficult to believe that a systemic disease causes” of pathologies because, until mid-20th such as tuberculosis does not degrade the quality century, the term “heredity,” especially in its lay of sperm and egg cells9. At first, Tredgold was a uses, englobed all the elements that could affect moderate eugenist. He did believe that the ma- the “quality of the seed” and fetal development. jority of inborn impairment were inherited, but Maternal conditions that may affect the fetus, also that society cannot do much to prevent them, such as syphilis, tuberculosis or alcoholism could mainly because impaired children are frequently therefore be described as “hereditary”3. born to parents who do not display marked signs In late 19th and early 20th century physicians – of “degeneration”. In the 1930s, perhaps under especially those linked with the rapidly growing the influence of ideas propagated by the German eugenic movement – were concerned by hered- Nazi and their British sympathizers, Tredgold ity of “feeble mindness”, and its potential threat changed his mind, and converted to the idea that to society4-7. The British psychiatrist George the sterilization of selected categories of “degen- Edward Shuttleworth (1842-1928), author of erates «and the prohibition of marriage of people the textbook, Mentally Deficient Children: Their from “tainted” families›› will reduce the burden Treatment and Training, proposed to distinguish of hereditary diseases in society”10. between “acquired mental deficiency,” produced Tredgold views on the effectiveness of eugen- by accidents of childbirth or childhood by events ic interventions such as sterilization to reduce such as trauma, a febrile disease or intoxication, the frequency of “feeble mindness” were strongly and “inborn mental deficiency,” produced before opposed by the British geneticist, Lionel Penrose birth by “formative defects”. Shuttleworth in- (1898-1972). Penrose coordinated in the 1930s a cluded in the latter category conditions such as large study on the possible inheritance of men- microcephalus (too small brain), hydrocephalus tal conditions, the Colchester Survey. In the final (the accumulation of liquid in the skull), “mon- report of this survey Penrose explained that very gol” feeblemindedness, (today, Down syndrome), few mental disorders, were truly “hereditary” that “cretinism” (today, thyroid insufficiency), and is, followed a Mendelian pattern of transmis- anomalies produced by diseases of the pregnant sion11. Among the latter he singled out two dis- woman, such as epilepsy, syphilis and eclampsia eases, Huntington’s chorea and phenylketonuria (seizures during pregnancy). Mental deficien- (PKU), both undoubtedly hereditary – and very cy which stems from “formative defects” (that rare. Penrose was especially interested in PKU, is, impairments acquired before birth) Shuttle- seen by him as an exemplary hereditary patholo- worth pointed out, is frequently associated with gy. PKU is produced by the organism’s decreased visible physical defects such as hare lip, deficient ability of metabolize the amino acid phenylal- ear lobes, missing fingers, unusual shape of face anine. The accumulation of phenyl alanine in or crane anomalies. A trained physician should the blood leads to intellectual impairment, sei- be able to recognize the physical traits of mental zures and behavioral problems. This condition deficiency even in relatively mild cases. Such traits was first described by the Norwegian physician are often more exaggerated in advanced cases8. and biochemist Ivar Asbjorn Folling in 193412. Shuttleworth saw “feeble mindness” as re- Penrose coined the name phenylketonuria and flecting a complex mixture of inherited and ac- demonstrated, thanks to the data collected by the 3609 Ciência & Saúde Coletiva, 24(10):3607-3617, 2019 24(10):3607-3617, Coletiva, & Saúde Ciência Colchester Survey, that it was a hereditary reces- digestive anomalies while others did not have sive disorder13,14. PKU was presented by Penrose such anomalies; some had very severe intellectu- as a rare case of heredity of a mental impairment, al limitations while others, especially when they and, at the same time, a strong argument against received well-adapted and compassionate educa- eugenicists’ claims. He had calculated that about tion (contrary to received ideas, already in the 19th 1% of the British people are carriers of the PKU century selected institutions and educations pro- trait. It was pointless to try to control the repro- vided such education) made important progress, duction of all the individuals with this trait, while and some were able to live quasi-autonomous controlling only the affected people (assuming lives and hold jobs. that they will have offspring in spite of their se- Researchers rapidly arrived to the conclu- vere mental impairment) would have practically sion that “mongolism” in all probability a shared no effect on the frequency of the “defective” gene biological basis, but also that it does not run in in Britain, and would