RESUMO
Familial cold autoinflammatory syndrome (FCAS) and Muckle-Wells syndrome (MWS) belong to the cryopyrin-associated periodic syndromes (CAPS) with CIAS1 gene mutations as a common molecular basis. Patients with FCAS have the least severe clinical phenotype but are characterized by the development of symptoms induced by a generalized exposure to cold appearing during the first months of childhood. It is important to make differential diagnosis between FCAS and acquired cold urticaria (ACU) and familial atypical cold urticaria (FACU). Muckle-Wells syndrome is characterized by recurrent fever and urticarial rash, progressive sensorineural deafness and the development of secondary amyloidosis, but it is not considered the most severe disease of this group. Sensorineural deafness and amyloidosis are the two major complications of MWS and determine poor prognosis of the disease.