In particular, the m.14582A>G/MT-ND6 variant, which is considered individually neutral, has been shown to act in a synergistic combination with the m.14258G>A when causing LHON [16], suggesting that SNPs may have an additive effect on mitochondria dysfunction such as in the subject MCI4, who also harbored the m.14053A>G/MT-ND5 variant, or in the background of a different haplogroup. This evidence concerns the gene MT-ND6 and Leber hereditary optic neuropathy.