SCN11A and familial episodic pain syndrome: Over the last two decades, advances in genetic testing have revealed that Nav1.9, Nav1.8, and Nav1.7 are associated with neuropathic pain disorders, including familial episodic pain syndrome (FEPS), small fiber neuropathy, paroxysmal extreme pain disorder, primary erythromelalgia, and congenital insensitivity to pain [2].