NLRP3 and cryopyrin-associated periodic syndrome: NLRP3 (the gene that encodes cryopyrin) was originally identified as the gene responsible for cryopyrin-associated periodic syndrome (CAPS) in which neutrophilic urticarial rash is the most common symptom.5 CAPS is caused by gain-of-function mutations in NLRP3 that cause constitutive activation of NLRP3 in the absence of second signals and secretion of IL-1β.