A SURF1 gene mutation presenting as isolated leukodystrophy.

Mitochondrial respiratory chain defects are increasingly recognized in patients with leukodystrophy. We report the first case of leukodystrophy with systemic cytochrome oxidase deficiency caused by a loss of function mutation in the SURF1 gene in a 2-year-old girl presenting with failure to thrive, global neurodevelopmental regression, and lactic acidosis. Although all previously reported mutations in the SURF1 gene have been found in patients with cytochrome oxidase (COX)-deficient Leigh syndrome, the phenotype associated with SURF1 protein deficiency should be extended to include leukodystrophy.