GENOTYPE-PHENOTYPE CORRELATION IN DUCHENNE BECKER MUSCULAR-DYSTROPHY PATIENTS SEEN AT LUCKNOW/

The molecular basis of two allelic forms of muscular dystrophy, Duchen ne (DMD) and Becker (BMD), has been explained by frame shift hypothesi s. In order to test this hypothesis, deletional mutations in 59 patien ts confirmed to have DMD and 11 BMD patients were analysed using multi plex polymerase chain reaction and Southern hybridization with dystrop hin cDNA probes. Translational reading frame of the dystrophin gene wa s derived from 'Border type' analysis of exons flanking the intragenic deletions. The correlation between genotype (reading frame) and pheno type (clinical severity) showed higher number of DMD patients (similar or equal to 20%) deviating from the frame shift hypothesis. The patie nts who deviated had deletions at the central hot spot region of the d ystrophin gene. The presence of these deviations in a large number of DMD patients highlights the difficulties in predicting the clinical pr ogression of the disease based only on DNA profile.