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.