The human SCN9A gene encodes the pore-forming subunit of Nav1.7, a voltage-gated sodium channel. Mutations in SCN9A channels have been linked to several inherited diseases including erythromelalgia (vasodilation with burning pain), paroxysmal extreme pain disorder, and congenital indifference to pain). Nav1.7, upregulated in prostatic cancer and inflammation, is a cancer biomarker and a therapeutic target in treatment of pain.