MFN2 and hereditary optic atrophy: Additional phenotypes found in patients with MFN2 variants include intellectual disability, optic atrophy (HMSN6), vocal cord palsy, spinal atrophy with or without hydromyelia, and hydrocephalus, all of which support the presence of central nervous system (CNS) involvement in CMT2A2 (Bombelli et al. 2014).