SERPING1 and hereditary angioedema: Introduction: Bradykinin-induced angioedema (BK-AE) can be due to a deficiency in the C1-esterase inhibitor (C1-INH), which may be hereditary (HAE-C1-INH) or acquired (AAE-C1-INH) or have normal C1-INH, that includes Hereditary Angioedema with F12 gene mutation (HAE-FXII), among others.