Charcot–Marie–Tooth Disease Type 1A (CMT1A) and Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) are the most common inherited peripheral neuropathies and arise from copy number variation of the Peripheral Myelin Protein 22 (PMP22) gene. The gene discussed is PMP22; the disease is Charcot-Marie-Tooth disease type 1A.