[Non-Fukuyama type merosin-positive congenital muscular dystrophy with delayed muscle fiber type differentiation: a case report].

A patient with non-Fukuyama type merosin-positive congenital muscular dystrophy (nonFCMD) who had severe muscle weakness leading to early death was reported. He was the first product of epileptic mother who had been placed on phenobarbital and phenytoin. The patient had severe respiratory failure and muscle weakness at the neonatal period, and died at 4 months of age. Multiple joint contractures were also noted at birth. Serum creatine kinase was within normal limits (123 IU/l). Electromyography showed a myogenic pattern. Brain computed tomographic (CT) scan and magnetic resonance imaging (MRI) were normal without white matter lucency or pachygyria. Muscle biopsy revealed dystrophic changes and type 2C fiber predominance. Dystrophin, dystrophin-associated glycoproteins and merosin were all positively demonstrated. Although patients with merosin-positive nonFCMD have relatively mild clinical course, our patient had severe muscle weakness with fatal outcome. Defect in muscle fiber maturation and differentiation, such as an increase of undifferentiated type 2C fibers, may be a major factor to influence muscle symptoms in non FCMD.