SERPING1 and hyperinsulinemic hypoglycemia, familial, 4: Hereditary angioedema (HAE) due to C1-inhibitor (C1-INH) deficiency (C1-INH-HAE) is a rare, potentially life-threatening disorder characterized by recurrent swelling episodes in subcutaneous and/or submucosal tissues, which are often preceded by prodromal symptoms [1, 2].