Selective defect of sarcoglycan complex in severe childhood autosomal recessive muscular dystrophy muscle.

Dystrophin-associated glycoprotein complex is classified into two subcomplexes: the dystroglycan complex (156DAG and 43DAG) and the sarcoglycan complex (50DAG, A3b, and 35DAG). Severe childhood autosomal recessive muscular dystrophy (SCARMD) was first reported to result from a deficiency of 50DAG. We examined muscles from five SCARMD patients and found that dystrophin and 43DAG were present in almost normal levels while 35DAG and the newly-identified protein A3b in addition to 50DAG were absent or greatly reduced. Therefore, SCARMD is the disease with a selective defect of the sarcoglycan complex.