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Reviewed December 2015
What is the official name of the C3 gene?
The official name of this gene is “complement component 3.”
C3 is the gene's official symbol. The C3 gene is also known by other names, listed below.
Read more about gene names and symbols on the About page.
What is the normal function of the C3 gene?
The C3 gene provides instructions for making a protein called complement component 3 (or C3). This protein plays a key role in a part of the body's immune response known as the complement system. The complement system is a group of proteins that work together to destroy foreign invaders (such as bacteria and viruses), trigger inflammation, and remove debris from cells and tissues.
The C3 protein is essential for turning on (activating) the complement system. The presence of foreign invaders triggers the C3 protein to be cut (cleaved) into two smaller pieces. One of these pieces, called C3b, interacts with several other proteins on the surface of cells to trigger the complement system's response. This process must be carefully regulated so the complement system targets only unwanted materials and does not damage the body's healthy cells.
Researchers have identified two major forms (allotypes) of the C3 protein, which are known as C3S and C3F. In the general population, C3S is more common than C3F. The two allotypes differ by a single protein building block (amino acid), although it is unclear whether they function differently.
Does the C3 gene share characteristics with other genes?
A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? in the Handbook.
How are changes in the C3 gene related to health conditions?
Genetics Home Reference provides additional information about these conditions associated with changes in the C3 gene:
Where is the C3 gene located?
Cytogenetic Location: 19p13.3-p13.2
Molecular Location on chromosome 19: base pairs 6,677,835 to 6,720,682
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The C3 gene is located on the short (p) arm of chromosome 19 between positions 13.3 and 13.2.
More precisely, the C3 gene is located from base pair 6,677,835 to base pair 6,720,682 on chromosome 19.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about C3?
You and your healthcare professional may find the following resources about C3 helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
What other names do people use for the C3 gene or gene products?
See How are genetic conditions and genes named? in the Handbook.
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding C3?
acids ; amino acid ; Asp ; atypical ; bacteria ; deficiency ; domain ; end-stage renal disease ; ESRD ; gene ; hydrolysis ; immune response ; immune system ; inflammation ; innate immunity ; kidney ; mutation ; population ; protein ; renal ; renal disease ; stage ; syndrome
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (5 links)
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? in the Handbook.