Mutations in sodium-channel gene SCN9A cause a spectrum of human genetic pain disorders

The voltage-gated sodium-channel type IX α subunit, known as Na v1.7 and encoded by the gene SCN9A, is located in peripheral neurons and plays an important role in action potential production in these cells. Recent genetic studies have identified Nav1.7 dysfunction in three different human pain disorders. Gain-of-function missense mutations in Na v1.7 have been shown to cause primary erythermalgia and paroxysmal extreme pain disorder, while nonsense mutations in Nav1.7 result in loss of Nav1.7 function and a condition known as channelopathy- associated insensitivity to pain, a rare disorder in which affected individuals are unable to feel physical pain. This review highlights these recent developments and discusses the critical role of Nav1.7 in pain sensation in humans.