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Complement deficiency is an immunodeficiency of absent or suboptimal functioning of ... The following symptoms ... C4: C4 deficiency is highly associated with ...
Complement tests C4 ... Complement 4 deficiency is a genetic condition affecting complement component 4. [1] It can present with lupus-like symptoms. [2 ...
Diagnosis usually consists of medical evaluation in addition to laboratory testing. Laboratory evaluation includes complement studies, in which typical cases demonstrate low C4 levels, low C1q levels, and normal C3 levels. [3] Determining the etiology, or cause, of acquired angioedema is often helpful in providing appropriate management of AAE.
Complement component 4 (C4), in humans, is a protein involved in the intricate complement system, originating from the human leukocyte antigen (HLA) system. It serves a number of critical functions in immunity, tolerance, and autoimmunity with the other numerous components.
For example, if and individual has normal C3/C4 values but a decreased CH50, that can indicate a terminal complement pathway deficiency while if one has low C3 and CH50 values that can indicate an autoimmune condition such as systemic lupus erythematosus.
The trimer provides a surface for interaction between the antigen-antibody complex and other complement components. The alpha chain may be cleaved to release C4 anaphylatoxin, a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus and type I diabetes mellitus.
Excessive complement activity contributes to severe Covid-19 symptoms and disease. [53] Although complement is intended to protect the body systems, under stress there can be more damage than protection. Research has suggested that the complement system is manipulated during HIV/AIDS, in a way that further damages the body. [54]
Deficiency of C1-inhibitor permits plasma kallikrein activation, which leads to the production of the vasoactive peptide bradykinin. Also, C4 and C2 cleavage goes unchecked, resulting in auto-activation of the complement system. In its most common form, it presents as marked swelling of the face, mouth and/or airway that occurs spontaneously or ...