MT-ND1 is a gene of the mitochondrial genome coding for the NADH-ubiquinone oxidoreductase chain 1 (ND1) protein. The ND1 protein is a subunit of NADH dehydrogenase, which is located in the mitochondrial inner membrane and is the largest of the five complexes of the electron transport chain. Variants of the human MT-ND1 gene are associated with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), Leigh's syndrome (LS), Leber's hereditary optic neuropathy (LHON) and increases in adult BMI.