[MIM*106100] a relatively rare form of edema characterized by onset, usually in childhood, of erythema followed by edema, involving the upper respiratory or gastrointestinal tract, associated with either a deficiency of C1 esterase inhibitor or a functionally inactive form of the inhibitor; may worsen during adolescence. There are two clinically indistinguishable forms: type I, in which the serum level of C1 esterase inhibitor is low (up to 30% of normal), and type II, in which the level is normal or elevated. There is uncontrolled activation of early complement components and production of a kininlike factor that induces the angioedema; death may occur from upper respiratory tract e. and asphyxia. Inheritance is autosomal dominant, caused by mutation in the C1-esterase inhibitor gene (C1NH) on chromosome 11q.