Mitochondrial optic neuropathies are inherited disorders of the optic nerve due to mitochondrial DNA (mtDNA) mutations affecting the mitochondrial-encoded subunits of complex I of the respiratory chain complex, pathogenic for Leber's hereditary Optic Neuropathy (LHON) or to mutations of the nuclear gene OPA1 causing Dominant Optic Atrophy (DOA) (46, 47). The gene discussed is OPA1; the disease is autosomal dominant optic atrophy.