Hereditary mitochondrial hypertrophic cardiomyopathy with mitochondrial myopathy of skeletal muscle, congenital cataract and lactic acidosis.

A six day old boy died from an hereditary hypertrophic cardiomyopathy which was associated with mitochondrial myopathy of skeletal muscle, congenital cataract and lactic acidosis. In heart and skeletal muscle identical mitochondrial abnormalities were found: paucity and abnormal arrangement of cristae, formation and extrusion of vesicle-like structures and crystalline inclusions in the matrix compartment. Electron-cytochemistry revealed that only part of the mitochondria reacted positively for cytochrome oxidase activity. Morphometric analysis indicated that the cardiomegaly was due to cellular hypertrophy, which might be caused by an increase in the mitochondrial mass. The cardiac hypertrophy in this syndrome can be classified histopathologically as mitochondrial hypertrophic cardiomyopathy.