[Inherited deficiency of the initiator molecules of the lectin-complement pathway].

The complement system is an important immune system. Its activation results in membranolytic elimination of microbes and opsonization. The classical, alternative and lectin pathways (LP) activate complement. Either mannan-binding lectin (MBL), ficolin-1, ficolin-2 or ficolin-3 initiate the LP through associated serine protease (MASP-2) after binding to microorganisms'surface carbohydrate patterns. Genetic polymorphisms behind MBL deficiency are rather common. Numerous studies indicate that MBL deficiency is a risk factor for invasive and recurrent infections, especially when other immune systems are immature, deficient or compromised. Research in ficolins is limited but last year ficolin-3 deficiency was described. This review focuses on these recently WHO defined immunodeficiencies.