DO_rare_slim mitochondrial complex I deficiency UMLS_CUI:C1838979 A mitochondrial metabolism disease characterized by a wide range of manifestations including marked and often fatal lactic acidosis, cardiomyopathy, leukoencephalopathy, pure myopathy and hepatopathy with tubulopathy. Among the numerous clinical phenotypes observed are Leigh syndrome, Leber hereditary optic neuropathy and MELAS syndrome. It can have material basis in mutations in multiple different genes, both nuclear-encoded and mitochondrial-encoded. GARD:3908 ORDO:2609 SNOMEDCT_US_2025_09_01:237988006 DOID:0060536 disease_ontology MESH:C537475 isolated NADH-CoQ reductase deficiency isolated NADH-coenzyme Q reductase deficiency isolated NADH-ubiquinone reductase deficiency isolated mitochondrial respiratory chain complex I deficiency mitochondrial metabolism disease