For example, mutations in PLEKHG5, encoding a GEF that regulates autophagy of synaptic vesicles in axonal terminals, cause recessive intermediate CMT (7), while variants in MYO9B, encoding a RhoGAP, have recently been shown to cause CMT type 2 (CMT2) and optic atrophy (8). Here, MYO9B is linked to Leber hereditary optic neuropathy.