MFN2 and autosomal dominant optic atrophy: Mitochondrial dynamics are represented by mitochondrial fission processes controlled by mitofusin 1 (MFN1), MFN2, OPA1 (a gene encoding a dynamin-like mitochondrial GTPase involved in autosomal dominant optic atrophy) and fusion processes regulated by: mitochondrial dynamics, mitochondrial mitophagy and mitochondrial biogenesis.