Possible X linked congenital mitochondrial cardiomyopathy in three families.

Familial cases of childhood congestive cardiomyopathy with X linked recessive inheritance and abnormalities of heart muscle mitochondria have been previously reported. We report here three families with possible X linked congestive cardiomyopathy and specific mitochondrial abnormalities. The heart disorder presented as endocardial fibroelastosis with neonatal death in two brothers in one family, and as heart failure and death in infancy in two brothers in the other two families. In one family a maternal uncle may also have been affected. Pyodermia and neutropenia was reported in one of the boys. Electron microscopy of heart muscle after necropsy showed increased numbers of mitochondria and abnormal mitochondrial crystal condensations and paracrystalline inclusions in all sibships. Barth's syndrome has been mapped to Xq28 and includes cardiomyopathy, skeletal muscle myopathy, neutropenia, and mitochondrial abnormalities similar to those found in the three families reported here. Since the clinical picture differed in the three families, they may represent more than one entity.