Mannan-binding lectin - associated serine protease 2 deficiency

Mannan-binding lectin associated serine protease (MASP-2) is homologous to MASP-1 and the two C1q-associated serine proteases C1r and C1s. When mannan-binding lectin binds to carbohydrate structures on microorganisms, the manan-binding lectin pathway of the complement system is activated. By autoactivating MASP2 cleaves complement factors C4 and C2, generating the C3 convertase C4bC2b. Activation of C3 initiates the alternative pathway and the formation of the membrane-attack complex. Phagocytosis and inflammatory reactions are facilitated by complement fragments deposited on microorganisms. The MASP-2 deficiency is associated with susceptibility to infections and with the development of immunologic disease.

Alternative names

Inherited deficiency of mannan-binding lectin-associated serin protease 2

MASP-2 deficiency


  • Complement regulatory proteins
    • Mannose-binding lectin deficiency


Autosomal recessive


*605102 Mannan-binding lectin serine protease 2; MASP2

Cross references

Phenotypically related immunodeficiencies

IDR factfile for Manose-binding lectin (protein) deficiency


Incidence is not known.