MT-ND4 and Leber hereditary optic neuropathy: The health problems of the individuals with m.9016A>G and m.9139G>A are thus likely to be caused by the primary mtDNA variants leading to LHON, also found in those two patients: m.14484T>C mutation in MT-ND6 and m.11778G>A mutation in MT-ND4 genes, respectively (La Morgia et al., 2008; Povalko et al., 2005).