Complement Deficiencies
Complement is a series of circulating enzymatic serum proteins with nine functional components, labeled C1 through C9. Complement deficiency or dysfunction may increase susceptibility to infection and seems to be related to certain autoimmune disorders.
Theoretically, any complement component may be deficient or dysfunctional, and many such disorders are under investigation. However, primary complement deficiencies are rare. The most common include C2, C6, and C8 deficiencies and C5 familial dysfunction. (See Major disorders associated with complement deficiencies, page 202.)More common secondary complement abnormalities have been confirmed in patients with lupus erythematosus, in some with dermatomyositis, in one with scleroderma (and in his family), and in a few patients with gonococcal and meningococcal infections.
The prognosis varies with the abnormality and the severity of associated diseases.
Causes
Primary complement deficiencies are inherited as autosomal recessive traits, except for deficiency of C1 esterase inhibitor,
which is autosomal dominant. Secondary deficiencies may follow complement-fixing (complement-consuming) immunologic reactions, such as drug-induced serum sickness, acute streptococcal glomerulonephritis, and acute active systemic lupus erythematosus.
which is autosomal dominant. Secondary deficiencies may follow complement-fixing (complement-consuming) immunologic reactions, such as drug-induced serum sickness, acute streptococcal glomerulonephritis, and acute active systemic lupus erythematosus.
Major disorders associated with complement deficiencies
A deficiency of a specific complement may be linked to a particular disorder. Study the following list to help you better understand this link.
|
