Our recent studies demonstrated that LHON-associated mtDNA mutations including ND1 3460G>A, ND6 14484T>C, and ND4 11778G>A mutations only accounted for 48% cases of a large cohort of 1,793 Chinese probands with optic atrophy (13–15, 29–30). The gene discussed is MT-ND4; the disease is Leber hereditary optic neuropathy.