Variable Presentation of Cytochrome c Oxidase Deficiency

To describe three patients with cytochrome c oxidase deficiency. —Patient series. —Tertiary care Children's hospital in Arkansas. —A sibling pair and an unrelated patient referred for evaluation and found to have cytochrome c oxidase deficiency. —None. —Affected individuals had the characteristic presentation of psychomotor regression, growth deficiency, and lactic acidosis. The severity of the clinical course was found to correlate with the lactatepyruvate ratio. Two of the infants had evidence, on magnetic resonance imaging, of subacute necrotizing encephalomyelopathy (Leigh disease). The most severely affected child had an unusual presentation of prenatal onset of structural anomalies including glabellar prominence, abnormal hair, loose skin, inguinal hernias, and hypospadias. —The presentation and clinical course of cytochrome coxidase deficiency are highly variable and the diagnosis of cytochrome c oxidase deficiency should be considered in all patients with lactic acidosis or subacute necrotizing encephalomyelopathy. Particular consideration should be given to this diagnosis when lactic acidosis is found in a neonate with structural anomalies.