MT-ND4 and Leber hereditary optic neuropathy: Since that time, five other complex I mutations have been confirmed to be clearly pathogenic in LHON (www.mitomap.org), a total of three mutations in polypeptides ND1 (G3460A) [5], ND4 (G11778A) [4] and ND6 (T14484C) [6] being responsible for 90-95% of all cases.