Definition: A group of rare autosomal dominant diseases, commonly characterized by atypical URTICARIA (hives) with systemic symptoms that develop into end-organ damage. The atypical hives do not involve T-cell or autoantibody. Cryopyrin-associated periodic syndrome includes three previously distinct disorders: Familial cold autoinflammatory syndrome; Muckle-Wells Syndrome; and CINCA Syndrome, that are now considered to represent a disease continuum, all caused by NLRP3 protein mutations.