OPA1 and autosomal dominant optic atrophy: Homozygous Opa1 mutant mice die in utero during embryogenesis, but heterozygous Opa1 mutants display the main features of human dominant optic atrophy including abnormal mitochondrial morphology, disorganized cristae structure, mitochondrial dysfunction and mtDNA instability (Alavi et al., 2007; Davies et al., 2007; Chen et al., 2012).