Sequential expression of genes involved in muscular dystrophies during human development.

To elucidate the normal and pathophysiological roles of genes involved in the aetiology of muscular dystrophies, we studied the expression of dystrophin, four sarcoglycans, beta-dystroglycan and merosin during early human development. These proteins are expressed mainly in skeletal muscles while dystrophin, beta-dystroglycan, delta-sarcoglycan and merosin are in cardiac and smooth muscles. Dystrophin, beta-, delta-sarcoglycan and beta-dystroglycan are first expressed in the myotome at the 4th week of human embryogenesis, followed by gamma-sarcoglycan and merosin at the 6th week of development; alpha-sarcoglycan appears only at the level of the muscular fibre at the end of the embryonic period.