Complement gene family

Reviewed June 2010

What are the complement genes?

Genes in the complement family provide instructions for making proteins involved in the complement system, an essential part of the body's immune response. The complement system is composed of more than 20 proteins that work together to destroy foreign invaders (such as bacteria and viruses), trigger inflammation, and remove debris from cells and tissues. This system must be carefully regulated so it targets only unwanted materials and does not attack the body's healthy cells.

Several diseases have been associated with changes in complement genes. Each of these genetic changes typically results in a shortage (deficiency) of a single complement system protein. These deficiencies disrupt the normal activity or regulation of the complement system, often leading to an increased risk of bacterial infection or recurrent episodes of severe swelling (angioedema). Complement system defects have also been found in autoimmune disorders such as systemic lupus erythematosus. Autoimmune disorders occur when the immune system malfunctions and attacks the body's own tissues and organs.

Which genes are included in the complement gene family?

The HUGO Gene Nomenclature Committee (HGNC) provides a list of genes in the complement family (http://www.genenames.org/genefamily/complement.php).

Genetics Home Reference summarizes the normal function and health implications of these members of the complement gene family: C3, CFH, CFHR5, and CFI.

What conditions are related to genes in the complement gene family?

Genetics Home Reference includes these conditions related to genes in the complement gene family:

age-related macular degeneration
atypical hemolytic-uremic syndrome
complement factor I deficiency
dense deposit disease

Where can I find additional information about the complement gene family?

You may find the following resources about the complement gene family helpful.

The Merck Manual for Healthcare Professionals (http://www.merckmanuals.com/professional/immunology_allergic_disorders/biology_of_the_immune_system/complement_system.html)
National Cancer Institute (http://www.cancer.gov/cancertopics/understandingcancer/immunesystem/page18)
OMMBID: Genetically Determined Disorders of the Complement System (http://books.mcgraw-hill.com/getommbid.php?isbn=0071459960&template=ommbid&c=186)
MedlinePlus Encyclopedia: Complement (http://www.nlm.nih.gov/medlineplus/ency/article/003456.htm)

What glossary definitions help with understanding the complement gene family?

autoimmune ; bacteria ; deficiency ; immune response ; immune system ; infection ; inflammation ; innate immunity ; lupus ; Mb ; protein ; systemic lupus ; systemic lupus erythematosus

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).

References

These sources were used to develop the Genetics Home Reference summary for the complement gene family.

Immunobiology (fifth edition, 2001): The Complement System and Innate Immunity (http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=imm&part=A161)
Rus H, Cudrici C, Niculescu F. The role of the complement system in innate immunity. Immunol Res. 2005;33(2):103-12. Review. (http://www.ncbi.nlm.nih.gov/pubmed/16234578?dopt=Abstract)
Thurman JM, Holers VM. The central role of the alternative complement pathway in human disease. J Immunol. 2006 Feb 1;176(3):1305-10. Review. (http://www.ncbi.nlm.nih.gov/pubmed/16424154?dopt=Abstract)
Chen M, Daha MR, Kallenberg CG. The complement system in systemic autoimmune disease. J Autoimmun. 2010 May;34(3):J276-86. doi: 10.1016/j.jaut.2009.11.014. Epub 2009 Dec 11. Review. (http://www.ncbi.nlm.nih.gov/pubmed/20005073?dopt=Abstract)

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.



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