OPA1 and Atrophy: MFN1/MFN2, mitofusin-1 and -2; OMM, outer mitochondrial membrane; IMM, inner mitochondrial membrane; ER, endoplasmic reticulum; CMT2A, Charcot–Marie–Tooth type 2A; HMSNs, hereditary motor and sensory neuropathies; OPA1, optic atrophy type 1; DRP1, dynamin-related protein-1; MFF, mitochondrial fission factor; FIS1, fission mitochondrial 1; MIEF1 /MIEF2, mitochondrial elongation factor 1 and 2; DNM2, dynamin 2; CNM1, centronuclear myopathy 1; DI-CMTB, dominant intermediate Charcot–Marie–Tooth disease type B; CMT2M, Charcot–Marie–Tooth disease axonal type 2M.