DUCHENNE AND BECKER MUSCULAR-DYSTROPHY PREVALENCE IN SOUTH-AFRICA ANDMOLECULAR FINDINGS IN 128 PERSONS AFFECTED

A genetic service for Duchenne muscular dystrophy (DMD) and Becker mus cular dystrophy (BMD) was initiated in Cape Town in 1987. Of the 143 D MD patients diagnosed during the period 1987-1992, 66 had a familial p attern of inheritance and 77 were apparently sporadic. Twenty BMD pati ents were identified, of whom 12 had other affected relatives and 8 we re sporadic. Overall minimum prevalence rates of 1/100 000 for DMD and 1/755 000 for BMD were calculated. A markedly low DMD prevalence in t he indigenous black population (1/250 000) contributed to the overall low DMD prevalence in South Africa when compared with that in the UK ( 1/40 000). By means of molecular methods, the diagnosis in 42% of the affected DMD males was confirmed by detection of deletions in the dyst rophin gene. Deletions were identified in 50% of Indian, white and mix ed ancestry patients. In contrast, only 22% of blacks had identifiable deletions. DMD appears to be underrepresented in the black population ; the low deletion frequency in this group suggests that unique mutati ons not detectable by methods used in this study may be more frequent in these patients than in the other populations. The increased DMD fre quency in Indians corroborates findings reported from the UK.