An exception is C1 inhibitor (C1inh) which is used to treat hereditary angioedema (HAE); HAE is triggered by a lack of C1inh which controls the contact-system protease, kallikrein, as wells as the activating complex of the classical pathway, C1; however, C1inh, either recombinant (Ruconest) or native (Cinryze, Berinert), is used to replace missing protein, rather than to block complement as a therapeutic target [24]. The gene discussed is SERPING1; the disease is hereditary angioedema.