MT-ATP6 and Leber hereditary optic neuropathy: Regarding the fourth MT-ATP6 variant (m.9029A>G), detected in an atypical LHON patient (with progressive loss of vision over 4 years) and in a second patient diagnosed with mitochondrial disorder, there is some evidence that it might have detrimental effects on mitochondrial function and was therefore suspected to be pathogenic (Lopez-Gallardo et al., 2014).