The pathogenesis of HNPP remains unclear, and it is widely accepted that reduced expression of PMP22 makes nerves more susceptible to conduction block when subjected to pressure or tension.[1] Facial nerves that have myelin sheath lesions and traverse bony canals may be more prone to slight pressure, which can result in facial paralysis. The gene discussed is PMP22; the disease is hereditary neuropathy with liability to pressure palsies.