SERPING1 and hereditary angioedema: ACEI-AE is more common (0.1–0.7% of treated patients) than other rare BK-mediated AE, such as hereditary angioedema (HAE), due to complement C1 esterase inhibitor (C1-INH) deficiency (1:10,000–1:50,000 prevalence), which is more common than acquired angioedema with C1 inhibitor deficiency (1:100,000 to 1:500,000 prevalence) [2,9,10].