Hereditary Angioedema: Improving Our Diagnosis and Therapeutic Decisions. Hereditary angioedema is an autosomal dominant disease caused by a functional or quantitative defect in C1 esterase inhibitor and is characterized by paroxysmal, intense, recurrent attacks of nonpruritic, nonpitting swelling of the subcutaneous tissue and mucous membranes, often of life-threatening severity. Primary care clinicians and pediatricians serve as a first line of defense for suspicion of HAE and thus can play an important role in preventing diagnostic delays that can lead to unnecessary surgery and other unintended comorbidities, and helping to treat and prevent attacks.