Dystrophin gene analysis and prenatal diagnosis of Duchenne muscular dystrophy in Russia.

Of 126 families referred for counselling of Duchenne muscular dystrophy (DMD), DNA analysis has been suggested to 119 families with at least one affected child or with an affected close male relative of the woman at risk of being a DMD carrier. A large proportion (about 80 per cent) of the families were represented by sporadic cases (only one affected individual). By means of multiplex polymerase chain reactions with different sets of oligoprimers providing amplification of 10-11 different exons, altogether 49 dystrophin gene deletions were identified (41 per cent). Eighteen deletions clustered in the 5' 'hot spot' region of DMD cDNA and 36 in the distal half of the central rod domain around exons 43-53. An unusually high frequency (18 per cent) of deletions involving exons 17-19 was discovered. Large deletions extending through both 'hot spot' regions and thus occupying over 30-40 exons were recorded in five cases (10 per cent). Seventy-six of 94 families were found to be informative by RFLP analysis for intragenic or extragenetic DNA probes. Carrier status was ascertained in 20 and rejected in 32 female relatives in 40 DMD families. Eight DMD-affected fetuses were diagnosed prenatally by direct deletion testing or by RFLP analysis. Feasible interpopulation variations in the dystrophin gene deletion pattern are discussed. The prospects for more effective prenatal diagnosis and carrier detection in high-risk DMD families in Russia are briefly outlined.