Clinical Characteristics

The syndrome caused by mutations in the NDUFS6 gene is a multisystem disorder (MIM618232) characterized by severe neonatal lactic acidemia and complex I deficiency leading to death in the first days of life in most of the described patients. Complex I deficiency is associated with a wide range of clinical presentations, including marked and often fatal lactic acidosis, cardiomyopathy, leukoencephalopathy, pure myopathy and hepatopathy with tubulopathy. Mutations in the NDUFS6 gene can also lead to Leigh syndrome. The symptoms of Leigh syndrome are highly variable, but usually include psychomotor arrest or regression, hypotonia, dystonia, seizures, ocular movements and, respiratory failure. Onset is typically between three and 12 months; about 50% of affected individuals die by age three years.