C1S and hereditary angioedema type 3: Strikingly, mutant FXII (Thr309Lys) from patients with hereditary angioedema type III (HAEIII), where O-linked glycosylation at position 309 is lost and inactivation by C1 esterase inhibitor during activation by plasmin is reduced (33, 34), is protected from CpaA inactivation (32).