Hypertrophic cardiomyopathy associated with a mitochondrial myopathy of voluntary muscles and congenital cataract.

Structurally abnormal mitochondria were found in skeletal muscle cells from a woman with hypertrophic cardiomyopathy and myopathy of voluntary muscles associated with congenital cataracts. Moderate exercise resulted in lactic acidosis. Oxidation of pyruvate and other substrates and the production of adenosine triphosphate were normal in vitro. A younger brother of the patient had had congenital cataract and had died from hypertrophic obstructive cardiomyopathy.