Pathogenesis of Physical Induced Urticarial Syndromes

Background: * Urticaria is a common itchy skin disorder that may occur spontaneously or on exposure to a physical trigger (called physical urticaria). * Researchers are studying the genetic basis of a physically induced urticarial syndrome. Once called familial cold urticaria, this condition is now called familial cold autoinflammatory syndrome (FCAS). FCAS is an autoinflammatory disease, a group of inherited disorders characterized by unprovoked episodes of inflammation. Patients with FCAS often have hives, joint pain, and fever following general exposure to cold. * Patients with FCAS have a mutation in a gene that makes a protein called cryopyrin. Cryopyrin seems to be involved with the production of a proinflammatory mediator called interleukin-1 (IL-1). Patients with FCAS and others with autoinflammatory syndromes have benefited from medication that blocks the effects of IL-1. Objectives: * To investigate mechanisms that may cause physical hives or urticaria. * To reproduce urticaria through challenge testing (procedures to test the skin for a reaction to a stimulus), followed by mast cell studies, measurement of IL-1, genetic studies, and other molecular studies to lead to a better understanding of urticaria and to design safe and more effective treatments. Eligibility: * Patients between 6 months and 65 years of age with a documented history of clinically reproducible physical urticaria that triggers hives and that has been evaluated by a physician. Patients should have a letter of referral, including copies of pertinent medical history and laboratory studies, from a referring physician. * Affected and nonaffected family members of such patients. * Exclusion criteria include (1) the presence of conditions that may put the subject at undue risk, such as acute infection, severe thrombocytopenia (a lower than normal number of platelets in the blood), or significant cardiovascular disease; (2) any condition that would make the subject unsuitable for enrollmen