Hereditary angioneurotic edema (HAE) It is caused by an inherited deficiency of C1 esterase inhibitor that results in excessive activation of the early components of the complement system and production of vasoactive mediators. Angioneurotic edema is classically non-pitting in nature. Uicaria(hives) may develop simultaneously, pruritus is not present. In severe cases, stridor of the airway occurs, with gasping or wheezy inspiratory breath sounds. It is an autosomal dominant disorder.