<unk>  is an immunodeficiency of absent or suboptimal functioning of one of the complement system proteins. Because of redundancies in the immune system, many complement disorders are never diagnosed. Some studies estimate that less than 10% are identified. Hypocomplementemia may be used more generally to refer to decreased complement levels, while secondary complement disorder means decreased complement levels that are not directly due to a genetic cause but secondary to another medical condition.
Complement deficiency
Complement 2 deficiency
Complement 3 deficiency
Terminal complement pathway deficiency
IgG deficiency
T cell deficiency
Neutrophil-specific granule deficiency
Leukocyte adhesion deficiency