MOLECULAR DELETION PATTERNS IN TURKISH DUCHENNE AND BECKER MUSCULAR-DYSTROPHY PATIENTS

The dystrophin gene deletion patterns of Duchenne/Becker muscular dyst rophy were investigated in 57 DMD, 7 BMD and 1 DMD-BMD intermediate mu scular dystrophy patients. Deletions, analyzed by multiplex amplificat ion of selected exons, were observed in 58% (38 cases) of the patients . It was found that exon 48 was the most frequently affected, while ex on 44 was the least frequently affected. The number of deleted exons w as variable, but single exon deletions were more frequent (41%) than l arger deletions in our population and the great majority of deletions began distal to exon 44. The application of PCR to deletion analysis i n D/BMD was found to be very useful in delineating the extent of the d eletion in most of the cases (82%). It was seen that the frequency of deletion breakpoints in distal part of the dystrophin gene (exons 42-5 2) was detected in 64% of our cases, In our group, the frequency of de letion breakpoints in the same area of the dystrophin gene was between that of the French and the Finnish patients. The distribution of dele tion breakpoints within the dystrophin gene of the Turkish population seems to have some differences from other populations. Deletion breakp oints were found to be clustered mainly in three separate regions cove ring introns 44, 45 and 50 within the central region of the dystrophin gene, Intron 44 was mostly 5' breakpoints but it was found not to be involved as 3' breakpoints. The correlation between phenotype and type of deletion agreed with the reading frame theory except for one DMD c ase.