Congenital nemaline myopathy with dilated cardiomyopathy: an autopsy study.

A 3-year-old boy with congenital nemaline myopathy had generalized muscle weakness and hypotonia since birth. He developed cardiac symptoms at 2 years of age and died from congestive heart failure. At autopsy, the heart was markedly dilated, involving both ventricles. Rod bodies were recognized not only in skeletal muscles but in cardiac muscles on light and electron microscopy. Desmin and alpha-actinin, which constitute Z-line protein, were shown to localize in the rod structures in both skeletal and myocardial cells by immunohistochemistry. Seven cases of nemaline myopathy with cardiomyopathy have been reported in the literature. All of these patients were over 20 years of age, and the condition appeared mostly in the adult onset and the asymptomatic forms. This is the first infantile case of congenital nemaline myopathy which showed dilated cardiomyopathy with a fatal outcome.