Angioedema accounts for 80,000 to 112,000 emergency department (ED) visits per year, with a hospitalization rate of 4.0 per 100,000 population.10–12 For patients taking angiotensin-converting enzyme inhibitors (ACEi), the incidence of angioedema ranges from 0.1–0.7% over a patient’s lifetime, while the prevalence of hereditary angioedema (HAE) ranges from 1 in 10,000 to 1 in 50,000 persons.6,10–15 Over 50% of patients with HAE require ED management, with over half of patients admitted to the hospital.1–3 ACEi-mediated angioedema accounts for 30% of angioedema cases. The gene discussed is ACE; the disease is angioedema.