Mutations in the NDUFV1 gene are associated with mitochondrial complex I deficiency and have been linked to various clinical conditions such as Leigh syndrome, severe infantile lactic acidosis, newborn cardiomyopathy, progressive leukoencephalopathy, and other encephalomyopathies. The gene discussed is NDUFV1; the disease is mitochondrial DNA depletion syndrome, encephalomyopathic form with methylmalonic aciduria.