[Importance of germ cell mosaic for genetic counseling of families with Duchenne and Becker muscular dystrophy].

Germ cell mosaics were demonstrated in Duchenne's and Becker's muscular dystrophy by molecular genetic methods. These findings affect risk estimates in these x-chromosomal muscular diseases. The mutation-selection equilibrium for x-chromosomally lethal inheritance for determining the a priori probability for risk estimate according to the Bayes theorem must therefore be redefined to take the germ cell mosaic problem into account. Taking Duchenne's and Becker's progressive muscular dystrophy as an example, the article explains how the estimation of the heterozygote risk in women seeking advice changes in different family situations.