Hereditary angioedema (HAE) is a rare genetic disorder characterized by recurrent attacks of cutaneous or submucosal edema associated with C1-inhibitor (C1-INH) deficiency (C1-INH-HAE type 1) or dysfunction (C1-INH-HAE type 2), leading to the overproduction of bradykinin, activation of bradykinin B2 receptors, capillary leakage, and local edema [1, 2]. The gene discussed is SERPING1; the disease is hyperinsulinemic hypoglycemia, familial, 4.