MT-ND4 and Leber hereditary optic neuropathy: Three primary mutations in MT-ND1 (m.3460G>A [p.Ala52Thr]), MT-ND4 (m.11778G>A [p.Arg340His]), and MT-ND6 (m.14484T>C [p.Met64Val]) account for 90%–95% of clinical cases of LHON (mitochondrial nucleotide numbering is based on GenBank: NC_012920).