SERPING1 and hereditary angioedema: A third type of HAE, in which both levels and function of C1-INH are normal (HAE-nl-C1INH) (2, 5), is associated with specific genetic mutations (i.e., F12, ANGPT1, HS3ST6, PLG, MYOF, and KNG1), although many patients with HAE-nl-C1INH have no currently identified genetic mutation (2, 6, 7).