RAB7A and Charcot-Marie-Tooth disease type 2B: Type 2B Charcot-Marie-Tooth disease (CMT2B) is caused by mutations in a residue of rab7A, a gene that encodes a small enzyme that is involved in regulating endosomes and lysosomes in all cells (Kwon et al., 1995; Elliott et al., 1997; Verhoeven et al., 2003).