Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is a rare multisystem genetic disorder characterized by unexplained periodic episodes or attacks of fever associated with additional symptoms including muscle pain (myalgia), abdominal pain, headaches and skin rashes. The specific symptoms can vary greatly from one person to another. The duration of the characteristic episodes can also vary, lasting anywhere from a couple days to one week to more than one month. Onset is usually during infancy or childhood. TRAPS is caused by mutations of the tumor necrosis factor receptor-1 (TNFRSF1A) gene that encodes the 55-kDa receptor for TNF.