Diffuse leukodystrophy in an infant with cytochrome-c oxidase deficiency.

A 25-month-old boy, born to consanguineous parents, had progressive spastic tetraplegia, and increased signal of the white matter on cerebral T2-weighted magnetic resonance imaging indicative of diffuse leukodystrophy. Elevated blood and cerebrospinal fluid lactate levels pointed to a respiratory chain defect. Cytochrome-c oxidase deficiency was demonstrated in cultured skin fibroblasts and skeletal muscle. This report extends the phenotype of COX deficiency in infancy. Systematic study of blood and CSF lactate should be carried out in every infant with leukodystrophy.