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.

Examples of genes in this gene family: C8A, C8B, CFH, CFHR5, CFI, ITGB2

The HUGO Gene Nomenclature Committee (HGNC) provides an index of gene families and their member genes.


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. PubMed: 20005073.

Rus H, Cudrici C, Niculescu F. The role of the complement system in innate immunity. Immunol Res. 2005;33(2):103-12. Review. PubMed: 16234578.

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. PubMed: 16424154.