Charcot-Marie-Tooth disease type 1 A (CMT1A) is the major subtype of hereditary peripheral neuropathies and arises from a 1.5 megabase (Mb) tandem duplication in chromosome 17p11.2-p12 that contains the complete peripheral myelin protein 22 (PMP22) gene. This evidence concerns the gene PMP22 and hereditary peripheral neuropathy.