LHON is caused by point mutations in mitochondrial DNA (mtDNA) genes encoding subunits of oxidative phosphorylation complex I. Most people with vision loss from LHON harbor one of three primary LHON mutations in MT-ND4 (m.11778G>A [p.Arg340His]),2 MT-ND6 (m.14484T>C [p.Met64Val]),3,4 or MT-ND1 (m.3460G>A [p.Ala52Thr]).5 This evidence concerns the gene MT-ND6 and Leber hereditary optic neuropathy.