19. H q PL e t a1 1985 P r o g r m and abstracts, Soc Mag Res Med, 4th annual meet ing, Lcndcn 20.Radda GK e t a1 1984 B r i t Med B u l l 40: 155 21. Siesjo BK 1978 Brain energy metabol ism. Chichester, Wi ley 22. T o f t s PS, Wray S 1985 J Physiol 359: 417 23. Yocnkin DP et al 1984 -I 16:581 24. Wllkie DR 1983 Blochem Soc Trans 2: 244 Workshop DNA Polymorphism and Detection of Genetic and Infectious Diseases DNA-Diagnosis of Hemoglobinopathias and Thalassemias JURGEN HORST Human Genetics Institute, University of Muenster, Muenster, BRD Hemoglobinopathias and thalassemias are the two major types of inherited disorders of hemoglobin i n man. While the hemo- globinopathias exhibit qualitative changes of the globin molecule, the thalassemias result from an imbalance i n a- and non-a-globin chain production. I n recent years the structural features of the normal human globin genes as well as the molecular lesions i n several hemoglobinopathias and many forms of thalassemias have been determined by the application o f recombinant DNA technology. While globin gene deletions are the predominant underlying molecular defects i n a-thalassemia ayndroms, the majority of hemoglobinopathias and B-thalassemias are due to point mutations within the respective globin gene regions. For diagnostic purposes the identification of mutant genes in cellular DNA is theoretically possible because of the direct or indirect specificity of restriction enzymes. A direct identi- fication of the defective gene can be made if the mutation changed an enzyme's cleavage s i t e and thus changes the normal DNA restriction pattern. For example, the direct detection of the sickle cell gene with restriction enzyme Mst I 1 and the hemo- globin (Hb) M Milwaukee gene with Sst I have recently been des- cribed (10,9,2,3,7). An indirect identification of chromosomes that carry a mutant gene relies on the presence of inherited DNA sequence polymorphisms within the cellular genome, giving rise to variations in restriction sites. Examples of this indirect diagnostic procedure are the identification of defective D-globin genes, causing hemoglobinopathias (e.g. Hb Freiburg, Hb Koln, Hb Presbyterian (8,4,5) or P-thalassemias (1,B)). A third possibility to identify chromosomes carrying point mutations or small deletions relies on oligonucleotide mapping procedures that have successfully been applied for diagnosis of some hemoglobinopathias and thalassemias. Here genotype analysis relies on the detection of normal homozygotes, heterozygotes and defective homozygotes exhibiting the respective three sets of intense, intermediate and missing band signals upon hybridization with oligonucleotides complementary to the normal or the mutated gene sequence. These experimental conditions can also be used i n diseases with an autosomal dominant inheritance pattern as i n the Hb Freiburg disorder, where normal homozygotes can be differ- entiated from Hb Freiburg patients (Horst et al. unpublished). All these methods have been applied for pre- and postnatal diagnostic purposes. In genetic counselling they have been used together with chorion biopsy or amniocentesis to provide prenatal diagnosis i n families at risk. I n the case of a-thalassemias prenatal diagnosis might only be applied to permit a mother with a fetus with hydrops fetalis to choose whether to carry the fetus through the full 9 month of pregnancy. However, together with hematological and family studies DNA-analysis data are especially useful to differentiate between a-thalassemla-1 and a-thalasse- mia-2 patients and thus to determine the exact diagnosis (6). Refe- 1. PntcnaWis StE, Kazazirn H1, Orkin StH 1985, Km Geret 69: 1 2. C h q X, Krn W 1982, N Em$ J kl 307: X) 3. tbrst J. Wfer R, Kleihaer E, Kdne E 1983, B r i t J km 54: 643 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 k t W 263 6. brst J, Griese EU, Kleihaer E, KdR E 1984, Hm h t 68: 260 7. Wm R, K~TE E, Klelhaer E, tbrst J 1983, Hm k t 64: 376 8. b R, 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. K i l s n JT, Mihr Ff, h r 8, M l l e t h FS, Fa&l K, Re~rrbllar l3l, Mh'w$ FG, Wilscn LB 19'82, Pnc M t l Pcaj %l US4 79: 3628 Molecular genetics of the X-linked muscular dystrophies KAY DAVIES, SARAH BALL, HUW DORKINS, SUSAN FORREST, SUSAN KENWRICK, ISABELLE LAVENIR, SUSAN McGLADE, TERRY SMITH AND LYNN WILSON Nufield Department of Clinical Medicine, John Radclzffe Hospital, Oxford OX3 9DU The w t a t i m s for Duchenne wscular dystrophy (DMD) and Becker wscular dystrophy (BW) have been localised t o the srme region of the short arm of the humn X c h r m s m at Xp21 by l lnkage analysis t o bridging CNA m r k e r s (1,2,3). Linkage studies shau thzt the frequency of recmbinatlm between wrkers in this regicn in 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) and in a Patient suffering frcm MD and glycerol kinase deficien- cy (81. The former has a visible cytogenetic deletim. This marker is linked at approxlmtely lOcM f r a t h e M locus <5,6). An ad- ditimal marker cn the opposite side of the WD and BMD loci also within Xp21 Is linked at a similar genetic distance (9). Althmgh these two markers together can nau be used for antenatal diagnosis (lo), m l y a few fan1 1ies can be helped. b r e closely I inked are being Identified. Strategies are nau being developed t o isolate additlmal se- quences localised within these deletims (11). These approaches should eventually lead to the identificatlm of the mlecular basis of M*D and BMD and permit the investlgatim of the observed high w t a t i m rate and the degree of heterogeneity of the mtaticns at the CNA level. REFERENCES 1. Kingston HM, Harper PS, P e a r s m PL, Davies KE, Wil l lamsm R , Page D 1983 Lccalisatim of the gene for Becker dystrophy. Lancet 2: 1200 2. Kingstm HM, T h m s NST, Pearsm PL, Sarfarazl M , Harper PS 1983 Genetlc linkage between Becker mscular dystrophy and a polymorphic CNA sequence m the short arm of the X chrmsaw. J Med Genet 20: 255-258 3. Davles, KE 1985 Molecular genetics of the hlman X chramsane. J Med Genet I n press 4. Davies, KE, Briand P , Imasescu, V , Imasescu G , Wi I1 ianscn R , B r m C , Cavard C, Cathelineau L 1985 Gene for OTC: characteri- satim and linkage t o Duchenne rmscular dystrophy. Nucl Acids Res 13: 155-165 5. Davies, KE, Speer A , H e r m n n F, S p i e g l e r AWJ, McGlade 5, Hofker W, B r l a n d P, Hanke, R, Schwartz M , S t e i n b l c k e r V, Szibor R, K o m e r H, Smr D , Pearsm PL, Catelle C 1985 H m X chrmscme wrkers and Duchenne mscular dystrophy. Nucl Acids Res 13: 3419-3426 6. B r m CS, Pearscn PL, T h m s NST, Sarfarazl M , Harper PS, Shaw DJ 1985 Linkage analysis of a M.IA polmrphism proximal to the Cuchenne and Becker mscular dystrophy loci m the short arm o f the X chraooscme. J Med Genet 22: 179-181 7. Francke U, Ochs HD, De M a r t i n v l l l e B, Giacalcne J, Lindgren V, Disteche C , Pagm RA, Hofker M, Van Chmm GJB, Pearscn PL, Wedgwood RJ 1985 Minor Xp21 c h r m s a w deleticn i n a male asso- ciated with expressicn of Duchenne rmscular dystrophy, chrcnic granulcmatous disease, r e t In1 t i s plgmntosa, and McLeod s y n d r m . Pm J Hun Genet 37: 250-268 8. Dunger DB, Davies KE, Pembrey ME, Lake BD, P e a r s m PL, Will im D , Whitfield T, D i l l m MJD 1985 A d e l e t i c n m the X c h r m s m detected by direct DNA analysls, in m e of two unrelated boys with glycerol kinase deficiency, adrenal hypopiasla and 'Du- chenne type' rmscular dystrophy. Submitted t o N Engl J Med 9. Dorklns HR, O l d JM, Mandel J-1, Bmdey S , Schwartz M , Carpenter NJ, Lindlof, M , De l a Chapel le, A , Kmkel L, Pearsm PL, Davies KE 1985 Segregatlm analysis of a marker localised Xp21.2-Xp21.3 In Cuchenne and Becker mscular dystrophy families. HUT Genet in press 10. Bakker, E, Hofker M-I, Goorl N, Mandel JL, Davies KE, Kunkel LM. Wi 1l a r d HF, Fentm WA , Sandkuy l L, Majoor-krakauer D , Van Essen A , Jahoda M , Sachs ES, Van Omlen GJB, Pearscn PL 1985 Prenatal diagnosis and carrier detectim of Duchenne mswular dystrophy with closely linked RFLPs. Lmcet 1: 655-658 11. LaMr EE, Palmer E 1984 Y-encoded, specles-specific DNA I n mice: evidence that the Y chraooscme exlsts in two polymsrphic forms in Inbred strains. Cell 37: 171-177 of the wtatims at the CNA l e v e l .