Among hereditary inflammatory disorders, Muckle-Wells syndrome, chronic infantile neurological cutaneous and articular syndrome (CINCA), and familial cold urticaria have recently been shown to be caused by dominantly inherited mutations in the CIAS1 gene. Reports suggest that these 3 diseases result from distinct missense mutations, with very few overlapping symptoms. We describe a French family presenting an intrafamilial overlapping clinical phenotype of CINCA and Muckle-Wells syndrome, caused by a mutation in CIAS1 gene. Clinical and genetic observations suggest that Muckle-Wells syndrome, CINCA, and familial cold urticaria are various phenotypic expressions of the same disease.