In the last three decades, a high variability of clinical manifestations has been observed in patients carrying MT-ATP6 variants, including bilateral striatal necrosis [101,140], Leber hereditary optic neuropathy (LHON) [93], adult-onset ataxia and polyneuropathy [141], schizophrenia [142], hereditary spastic paraplegia [102], spinocerebellar ataxia [108], Charcot–Marie–Tooth disease [105], mitochondrial myopathy, lactic acidosis and sideroblastic anemia (MLASA) [54], and motor neuron syndrome [143]. This evidence concerns the gene MT-ATP6 and Leber hereditary optic neuropathy.