Mondo Description A very rare inherited metabolic disorder characterized by deficiency of the enzyme cytochrome-C oxidase. It may be manifested as an isolated myopathy or a systemic disorder. Signs and symptoms include myotonia, dysfunction of the heart, kidney, and brain, and lactic acidosis.

Uniprot Description A disorder of the mitochondrial respiratory chain with heterogeneous clinical manifestations, ranging from isolated myopathy to severe multisystem disease affecting several tissues and organs. Features include hypertrophic cardiomyopathy, hepatomegaly and liver dysfunction, hypotonia, muscle weakness, exercise intolerance, developmental delay, delayed motor development and mental retardation. Some affected individuals manifest a fatal hypertrophic cardiomyopathy resulting in neonatal death. A subset of patients manifest Leigh syndrome.