Merosin-positive congenital muscular dystrophy with mental retardation and cataracts: a new entity in two families.

Merosin-positive congenital muscular dystrophy is a heterogenous group of disorders with varying clinical presentations and severity. In general, central nervous system involvement is not present. There is also evidence for still unclassified forms. Here we report three cases in two families with merosin-positive congenital muscular dystrophy, mild mental retardation, bilateral cataracts and normal cranial magnetic resonance imaging. To our knowledge, such an association has not been reported previously, and thus is a new entity within congenital muscular dystrophy nosology.