C3 deficiency

Complement component 3 occupies a central position in the complement pathway, mediating convertase activity, opsonization, anaphylotoxin production, B cell activation and immunoglobulin production, immune-complex clearance and adjuvant production. C3 gene is structurally related to C4 and alfa macroglobulin. It is produced in a wide variety of tissues and is an acute phase reactant. C3 deficiency is a rare autosomic recessive inherited disease, characterized by severe recurrent infections and immune-complex disorders.

Alternative names

Complement component 3 deficiency, autosomal recessive


  • Defects of the classical complement cascade proteins


Autosomal recessive


+120700 Complement component 3; C3

Cross references

Phenotypically related immunodeficiencies

IDR factfile for C2 deficiency


Incidence is not known.