NLRP3 and familial cold autoinflammatory syndrome 3: Familial atypical cold urticaria (FACU), first described in 2009, is characterized by early onset, lifelong persistence, hypersensitivity to atmospheric cold with a negative cold stimulation test (CSTT), and the absence of systemic inflammation [6]; familial cold autoinflammatory syndrome (FCAS), classically caused by gain-of-function mutations in NLRP3 with activation of the NLRP3 inflammasome, presents with cold-induced urticarial rash, fever, arthralgia, and elevated inflammatory markers [3].