MT-ND4 and Leber hereditary optic neuropathy: The majority of LHON cases (90–95%) are attributed to one of three primary mutations within complex I: (1) m.3460G>A, affecting the mitochondrial encoded NADH-ubiquinone oxidoreductase chain (MTND) 1 subunit; (2) m.11778G>A, impacting MTND4; and (3) m.14484T>C, influencing MTND6 [484].