MT-ND6 and Leber hereditary optic neuropathy: We also screened by complete mtDNA sequencing our entire cohort of LHON probands with one of the three known primary mutations (n = 236), finding the m.14258G>A/MT-ND6 variant in two further families, carrying the m.11778G>A /MT-ND4 (haplogroup T1a1) and m.14484T>C/MT-ND6 (haplogroup L2a1a1) LHON mutations, respectively (Families 3 and 4; S1 and S2 Figs).