Autosomal dominant axonal Charcot-Marie-Tooth disease type 2 (CMT2G) maps to chromosome 12q12-q13.3.

C harcot-Marie-Tooth (CMT) disease is a clinically and genetically heterogeneous group of disorders that involve the peripheral nervous system. It is characterised by progressive distal neurogenic muscular atrophy and weakness that initially affects the peroneal muscles and later the hands. Charcot-Marie-Tooth disease type 1 (CMT1), also called hereditary motor and sensory neuropathy type I (HMSN I), is a dominantly inherited demyelinating neuropathy characterised by reduced nerve conduction velocities (NCV) (motor median NCV ,38 m/s). Charcot-Marie-Tooth disease type 2 (CMT) 2, or HMSN II, is a dominantly inherited axonal neuropathy characterised by normal or slightly reduced NCV. Both autosomal dominant CMT1 and autosomal dominant CMT2 are genetically heterogeneous, with five and six loci, respectively. Most patients with CMT1 have a 1.4 Mb tandem duplication on chromosome 17p11.2 (CMT1A (MIM 118220)). 4 Other patients with CMT1 may have point mutations in the peripheral myelin protein 22 gene (PMP22 in CMT1A (MIM 60197)), myelin protein zero gene (MPZ in CMT1B (MIM 159440)), lipopolysaccharide induced tumour necrosis factor gene (LITAF in CMT1C (MIM 603795)), early growth response 2 gene (EGR2 in CMT1D (MIM 129010)), or the gap junction protein beta 1 gene (GJB1 in CMT1X (MIM 304040)). Patients with CMT2 may have point mutations in the kinesin family member 1B gene (KIF1B in CMT2A (MIM 605995)), RAB7, member RAS oncogene family (RAB7 in CMT2B (MIM 602298)), glycyl tRNA synthetase (GARS in CMT2D (MIM 600287)), or neurofilament light polypeptide (NEFL in CMT2E (MIM 607684)). The genes for CMT2C and CMT2F have not been identified yet. 15 Some patients with CMT2 have also been reported to have specific mutations in the MPZ gene. 17