SERPING1 and hereditary angioedema: There are three forms of HAE: type I is the most common, affecting from 80% to 85% of HAE patients and characterized by C1-INH deficiency; type II, found in 15–20% subjects, is characterized by C1-INH dysfunction; and the rare type III, which is typically estrogen-dependent with normal C1-INH activity and levels but brought about due to several gene mutations [2].