Factor H also acts as a cofactor for factor I-catalyzed C3b cleavage, degenerating iC3b, which cannot bind factor B. MASP-2 and factor H are mainly produced in the liver, and circulating complement factors are associated with several diseases, such as inflammatory, kidney, and infectious diseases, including coronavirus disease 2019.[18], [19], [20], [21]. The gene discussed is CFH; the disease is infectious disease.