Paroxysmal extreme pain disorder

Paroxysmal extreme pain disorder, originally named familial rectal pain syndrome, is a rare disorder whose most notable features are pain in the jaw, eye and rectal areas together with flushing. It often first appears at the beginning of life, possibly even before birth, and the symptoms persist throughout life. Its episodes of flushing and pain resemble those of primary erythromelalgia, though in that disorder the pain is typically in the extremities. Both disorders have been shown to be allelic, each caused by different mutations in the voltage-gated sodium channel NaV1.7 encoded by the gene SCN9A, and yet another mutation in the same gene causes congenital insensitivity to pain. It is abbreviated PEPD.