The homoplasmic or nearly homoplasmic ND4 11778G > A, ND1 3460G > A, and ND6 14484T > C mutations, which affects the essential component of complex I (NADH: ubiquinone oxidoreductase), accounted for the majority of LHON cases worldwide [118–123]. Here, MT-ND4 is linked to Leber hereditary optic neuropathy.