In particular, LHON pathogenic mutations are frequently homoplasmic and, in some cases, their pathogenicity has not been readily recognized.[2][3] Now we know that over 90% of LHON patients are due to three common mtDNA point mutations m.11778G>A/MT-ND4, m.3460G>A/MT-ND1 and m.14484T>C/MT-ND6 [4][5]. The gene discussed is MT-ND6; the disease is Leber hereditary optic neuropathy.