Charcot–Marie-Tooth type 1 are inherited demyelinating diseases affecting peripheral nerves which are caused in most patients by mutations in Pmp22 (CMT1A), MPZ (CMT1B), and GJB1 genes (CMT1X; see for review Suter and Scherer, 2003). The gene discussed is MPZ; the disease is Charcot-Marie-Tooth disease type 1.