MT-ND6 and Leber hereditary optic neuropathy: Furthermore, in both index patients, the three LHON mutations m.11778G > A, p.(Arg340His) in MTND4, m.3460G > A, p.(Ala52Thr) in MTND1 and m.14484 T > C, p.(Met64Val) in MTND6 were not detected.