19. HqPL et a1 1985 Progrm and abstracts, Soc Mag Res Med, Molecular genetics of the X-linked muscular dystrophies 4th annual meet ing, Lcndcn 20.Radda GK et a1 1984 Brit Med Bull 40: 155 21. Siesjo BK 1978 Brain energy metabol ism. Chichester, Wi ley KAY DAVIES, SARAH BALL, HUW DORKINS, 22. Tofts PS, Wray S 1985 J Physiol 359: 417 23. Yocnkin DP et al 1984 -I 16:581 SUSAN FORREST, SUSAN KENWRICK, 24. Wllkie DR 1983 Blochem Soc Trans 2: 244 ISABELLE LAVENIR, SUSAN McGLADE, TERRY SMITH AND LYNN WILSON Workshop Nufield Department of Clinical Medicine, John Radclzffe DNA Polymorphism and Detection of Genetic Hospital, Oxford OX3 9DU The wtatims for Duchenne wscular dystrophy (DMD) and Becker and Infectious Diseases wscular dystrophy (BW) have been localised to the srme region of the short arm of the humn X chrmsm at Xp21 by l lnkage DNA-Diagnosis of Hemoglobinopathias and analysis to bridging CNA mrkers (1,2,3). Linkage studies shau thzt the frequency of recmbinatlm between wrkers in this regicn in Thalassemias the families segregating for these disorders is high (4,5,6). Q7e marker in particular is deleted in both a patient suffering frar B'D, chronic granulcnatous disease and retinitis pigmentosa (7) JURGEN HORST and in a Patient suffering frcm MD and glycerol kinase deficien- cy (81. The former has a visible cytogenetic deletim. This marker Human Genetics Institute, University of Muenster, Muenster, is linked at approxlmtely lOcM frathe M locus <5,6). An ad- BRD ditimal marker cn the opposite side of the WD and BMD loci also within Xp21 Is linked at a similar genetic distance (9). Althmgh Hemoglobinopathias and thalassemias are the two major types these two markers together can nau be used for antenatal diagnosis of inherited disorders of hemoglobin in man. While the hemo- (lo), mly a few fan1 1ies can be helped. bre closely Iinked are globinopathias exhibit qualitative changes of the globin molecule, being Identified. the thalassemias result from an imbalance in a- and non-a-globin Strategies are nau being developed to isolate additlmal se- chain production. In recent years the structural features of the quences localised within these deletims (11). These approaches normal human globin genes as well as the molecular lesions in should eventually lead to the identificatlm of the mlecular several hemoglobinopathias and many forms of thalassemias have basis of M*D and BMD and permit the investlgatim of the observed been determined by the application of recombinant DNA technology. high wtatim rate and the degree of heterogeneity of the mtaticns While globin gene deletions are the predominant underlying at the CNA level. molecular defects in a-thalassemia ayndroms, the majority of REFERENCES hemoglobinopathias and B-thalassemias are due to point mutations 1. Kingston HM, Harper PS, Pearsm PL, Davies KE, Will lamsm R, within the respective globin gene regions. Page D 1983 Lccalisatim of the gene for Becker dystrophy. For diagnostic purposes the identification of mutant genes Lancet 2: 1200 in cellular DNA is theoretically possible because of the direct 2. Kingstm HM, Thms NST, Pearsm PL, Sarfarazl M, Harper PS or indirect specificity of restriction enzymes. A direct identi- 1983 Genetlc linkage between Becker mscular dystrophy and a fication of the defective gene can be made if the mutation polymorphic CNA sequence m the short arm of the X chrmsaw. changed an enzyme's cleavage site and thus changes the normal DNA J Med Genet 20: 255-258 restriction pattern. For example, the direct detection of the 3. Davles, KE 1985 Molecular genetics of the hlman X chramsane. sickle cell gene with restriction enzyme Mst I1 and the hemo- J Med Genet In press globin (Hb) M Milwaukee gene with Sst I have recently been des- 4. Davies, KE, Briand P, Imasescu, V, Imasescu G, Wi I1ianscn R, cribed (10,9,2,3,7). An indirect identification of chromosomes Brm C, Cavard C, Cathelineau L 1985 Gene for OTC: characteri- that carry a mutant gene relies on the presence of inherited DNA satim and linkage to Duchenne rmscular dystrophy. Nucl Acids sequence polymorphisms within the cellular genome, giving rise Res 13: 155-165 to variations in restriction sites. Examples of this indirect 5. Davies, KE, Speer A, Hermnn F, Spiegler AWJ, McGlade 5, diagnostic procedure are the identification of defective D-globin Hofker W, Brland P, Hanke, R, Schwartz M, Steinblcker V, genes, causing hemoglobinopathias (e.g. Hb Freiburg, Hb Koln, Szibor R, Komer H, SmrD, Pearsm PL, Catelle C 1985 Hm Hb Presbyterian (8,4,5) or P-thalassemias (1,B)). X chrmscme wrkers and Duchenne mscular dystrophy. Nucl Acids A third possibility to identify chromosomes carrying point Res 13: 3419-3426 mutations or small deletions relies on oligonucleotide mapping 6. Brm CS, Pearscn PL, Thms NST, Sarfarazl M, Harper PS, Shaw procedures that have successfully been applied for diagnosis of DJ 1985 Linkage analysis of a M.IA polmrphism proximal to the some hemoglobinopathias and thalassemias. Here genotype analysis Cuchenne and Becker mscular dystrophy loci m the short arm relies on the detection of normal homozygotes, heterozygotes and of the X chraooscme. J Med Genet 22: 179-181 defective homozygotes exhibiting the respective three sets of 7. Francke U, Ochs HD, De Martinvllle B, Giacalcne J, Lindgren V, intense, intermediate and missing band signals upon hybridization Disteche C, Pagm RA, Hofker M, Van Chmm GJB, Pearscn PL, with oligonucleotides complementary to the normal or the mutated Wedgwood RJ 1985 Minor Xp21 chrmsaw deleticn in a male asso- gene sequence. These experimental conditions can also be used in ciated with expressicn of Duchenne rmscular dystrophy, chrcnic diseases with an autosomal dominant inheritance pattern as in granulcmatous disease, ret In1t is plgmntosa, and McLeod syndrm. the Hb Freiburg disorder, where normal homozygotes can be differ- Pm J Hun Genet 37: 250-268 entiated from Hb Freiburg patients (Horst et al. unpublished). 8. Dunger DB, Davies KE, Pembrey ME, Lake BD, Pearsm PL, Willim All these methods have been applied for pre- and postnatal D, Whitfield T, Dillm MJD 1985 A deleticn m the X chrmsm diagnostic purposes. In genetic counselling they have been used detected by direct DNA analysls, in me of two unrelated boys together with chorion biopsy or amniocentesis to provide prenatal with glycerol kinase deficiency, adrenal hypopiasla and 'Du- diagnosis in families at risk. In the case of a-thalassemias chenne type' rmscular dystrophy. Submitted to N Engl J Med prenatal diagnosis might only be applied to permit a mother with 9. Dorklns HR, Old JM, Mandel J-1, Bmdey S, Schwartz M, Carpenter a fetus with hydrops fetalis to choose whether to carry the fetus NJ, Lindlof, M, De la Chapel le, A, Kmkel L, Pearsm PL, Davies through the full 9 month of pregnancy. However, together with KE 1985 Segregatlm analysis of a marker localised Xp21.2-Xp21.3 hematological and family studies DNA-analysis data are especially In Cuchenne and Becker mscular dystrophy families. HUT Genet useful to differentiate between a-thalassemla-1 and a-thalasse- in press mia-2 patients and thus to determine the exact diagnosis (6). 10. Bakker, E, Hofker M-I, Goorl N, Mandel JL, Davies KE, Kunkel LM. Wi 1lard HF, Fentm WA, Sandkuy l L, Majoor-krakauer D, Van Essen Refe- A, Jahoda M, Sachs ES, Van Omlen GJB, Pearscn PL 1985 Prenatal 1. PntcnaWis StE, Kazazirn H1, Orkin StH 1985, Km Geret 69: 1 diagnosis and carrier detectim of Duchenne mswular dystrophy 2. ChqX, Krn W 1982, N Em$ J kl 307: X) 3. tbrst J. Wfer R, Kleihaer E, Kdne E 1983, Brit J km 54: 643 with closely linked RFLPs. Lmcet 1: 655-658 11. LaMr EE, Palmer E 1984 Y-encoded, specles-specific DNA In mice: 4. turst J, Uehre R, Kle-r E, KdR E 1984, Blut 48: 213 5. brst J, Wm R, Klelkr E, K~YI? E 1983, Km ktW 263 evidence that the Y chraooscme exlsts in two polymsrphic forms 6. brst J, Griese EU, Kleihaer E, KdR E 1984, Hm ht68: 260 in Inbred strains. Cell 37: 171-177 of the wtatims at the 7. Wm R, K~TEE, Klelhaer E, tbrst J 1983, Hm kt64: 376 CNA level. 8. bR, Kdne E, brst J, shnitted for pblicatim 9. Drkin W, Little FfR, Kazazlan Hi Jr, Boehn a) 1582, N Er@ J M M7: 32 10. Kilsn JT, Mihr Ff, hr8, Mlleth FS, Fa&l K, Re~rrbllarl3l, Mh'w$ FG, Wilscn LB 19'82, Pnc Mtl Pcaj %l US4 79: 3628 .