Editing Complement system (section)

=== Deficiencies in complement regulators ===

Mutations in the genes of complement regulators, especially [[factor H]], have been associated with atypical [[hemolytic uremic syndrome]],<ref name=":0" /><ref name="pmid16189652">{{Cite journal |vauthors=Dragon-Durey MA, Frémeaux-Bacchi V |date=November 2005 |title=Atypical haemolytic uraemic syndrome and mutations in complement regulator genes |journal=Springer Seminars in Immunopathology |volume=27 |issue=3 |pages=359–74 |doi=10.1007/s00281-005-0003-2 |pmid=16189652 |s2cid=6330326}}</ref><ref name="pmid16575689">{{Cite journal |vauthors=Zipfel PF, Misselwitz J, Licht C, Skerka C |date=March 2006 |title=The role of defective complement control in hemolytic uremic syndrome |journal=Seminars in Thrombosis and Hemostasis |volume=32 |issue=2 |pages=146–54 |doi=10.1055/s-2006-939770 |pmid=16575689 |s2cid=260316508}}</ref> and C3 glomerulopathy.<ref name=":0" /> Both of these disorders are currently thought to be due to complement overactivation either on the surface of host cells or in plasma, with the molecular location of genetic variation in complement proteins providing clues into the underlying disease processes.<ref name=":0" /> Moreover, several [[single nucleotide polymorphism]]s and mutations in the complement factor H gene (the most common of which results in the protein change p.Y402H) have been associated with the common eye disease [[age-related macular degeneration]].<ref name=":0" /> Polymorphisms of [[complement component 3]], [[complement factor B]], and [[complement factor I]], as well as deletion of complement factor H-related 3 and complement factor H-related 1, also affect a person's risk of developing [[age-related macular degeneration]].<ref name=":0" /><ref name="BradleyDT2011">{{Cite journal |vauthors=Bradley DT, Zipfel PF, Hughes AE |date=June 2011 |title=Complement in age-related macular degeneration: a focus on function |journal=Eye |volume=25 |issue=6 |pages=683–93 |doi=10.1038/eye.2011.37 |pmc=3178140 |pmid=21394116}}</ref>

Mutations in the C1 inhibitor gene can cause [[hereditary angioedema]], a genetic condition resulting from reduced regulation of [[bradykinin]] by C1-INH.{{citation needed|date=May 2015}}

[[Paroxysmal nocturnal hemoglobinuria]] is caused by complement breakdown of [[Red blood cell|RBC]]s due to an inability to make GPI. Thus the RBCs are not protected by GPI anchored proteins such as DAF.<ref>{{Cite journal |display-authors=6 |vauthors=Parker C, Omine M, Richards S, Nishimura J, Bessler M, Ware R, Hillmen P, Luzzatto L, Young N, Kinoshita T, Rosse W, Socié G |date=December 2005 |title=Diagnosis and management of paroxysmal nocturnal hemoglobinuria |journal=Blood |volume=106 |issue=12 |pages=3699–709 |doi=10.1182/blood-2005-04-1717 |pmc=1895106 |pmid=16051736}}</ref>