[Non-Fukuyama type congenital muscular dystrophy--merosin deficient and positive forms]

The classical form of congenital muscular dystrophy (CMD) is now classified into merosin-deficient and -positive forms. The merosin (laminin alpha 2) is one of three subunits of a muscle basement membrane protein, laminin. Patients with the merosin-deficient form have generalized muscle weakness and hypotonia from early infancy as seen in FCMD but with no significant central nervous system involvement. The serum creatine kinase (CK) is markedly elevated. Strikingly all patients examined by a CT/ MRI have diffuse white matter abnormalities mimicking leukodystrophy. The gene has been mapped to chromosome 6q2 in the coding region for merosin. Since the responsible gene and protein have not been identified in the merosin-positive form, this CMD is probably a group of heterogeneous diseases. The overall symptoms are mild, approximately 90% of patients learned to walk alone.