Cytochrome C oxidase deficiency and Long-Chain acyl coenzyme A dehydrogenase deficiency with Leigh's subacute necrotizing encephalomyelopathy

A female infant was seen at the age of 2 months because of hypotonia, delayed motor development, and lactic acidosis, and she died at age 13 months due to respiratory failure. In a muscle specimen taken at 11 months and in a liver specimen obtained 1.5 hours postmortem, we found decreased activities of cytochrome c oxidase and longchain acyl coenzyme A dehydrogenase. Neuropathological changes were typical for Leigh's subacute necrotizing encephalomyelopathy. To our knowledge, this is the first report of a combined defect of complex IV of the respiratory chain and of the long‐chain specific acyl coenzyme A dehydrogenase of β‐oxidation in muscle and liver.