PMP22 is an example of a single gene that produces similar but distinguishable peripheral neuropathies in both a 1.5 Mb microdeletion (Charcot-Marie-Tooth syndrome type 1A, CMT1A) and a reciprocal microduplication (hereditary neuropathy with liability to pressure palsies, HNPP) due to disruption of peripheral nerve myelination38. The gene discussed is PMP22; the disease is peripheral neuropathy.