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Reviewed December 2015
What is the official name of the C8B gene?
The official name of this gene is “complement component 8, beta polypeptide.”
C8B is the gene's official symbol. The C8B 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 C8B gene?
The C8B gene provides instructions for making one piece, the beta subunit, of a protein complex called complement component 8. To form this complex, the beta subunit interacts with another piece made up of the alpha subunit (produced from the C8A gene) and the gamma subunit (produced from the C8G gene), which are linked.
Complement component 8 aids 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, trigger inflammation, and remove debris from cells and tissues. Complement component 8 combines with several other complement proteins to form the membrane attack complex (MAC), which inserts itself in the outer membrane of bacterial cells. This complex creates a hole (pore) in the membrane, which kills the bacterium. This part of the immune response appears to be especially important for fighting infection by bacteria in the Neisseria genus.
Does the C8B gene share characteristics with other genes?
The C8B gene belongs to a family of genes called complement (complement system).
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 C8B gene related to health conditions?
- complement component 8 deficiency - caused by mutations in the C8B gene
- Several mutations in the C8B gene cause complement component 8 deficiency type II. This condition is an immune system disorder, known as an immunodeficiency, in which the immune system is not able to protect the body effectively from foreign invaders such as bacteria. People with complement component 8 deficiency have a significantly increased risk of developing recurrent infections, particularly by Neisseria meningitidis, which causes meningitis, a serious condition that involves inflammation of the membranes surrounding the brain and spinal cord.C8B gene mutations involved in complement component 8 deficiency are most often of a type called a C to T transition, in which a DNA building block (nucleotide) called cytosine (C) is changed to the nucleotide thymine (T). Most commonly, this change occurs in a region of the gene called exon 9, but it can occur in other regions. These mutations alter the sequence of protein building blocks, resulting in an abnormally short protein that, if produced, is likely broken down quickly. Other types of mutations can occur in the C8B gene; they also lead to an abnormally short protein that is quickly broken down. The resulting shortage of this protein impairs formation of complement component 8. Deficiency of this component prevents formation of membrane attack complexes. Without this part of the immune response, affected individuals are prone to infection, particularly by Neisseria bacteria.
Where is the C8B gene located?
Cytogenetic Location: 1p32.2
Molecular Location on chromosome 1: base pairs 56,929,210 to 56,966,140
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The C8B gene is located on the short (p) arm of chromosome 1 at position 32.2.
More precisely, the C8B gene is located from base pair 56,929,210 to base pair 56,966,140 on chromosome 1.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about C8B?
You and your healthcare professional may find the following resources about C8B 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 C8B gene or gene products?
- complement component 8 subunit beta
- complement component C8 beta chain isoform 1 preproprotein
- complement component C8 beta chain isoform 2
- complement component C8 beta chain isoform 3
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.
- What is DNA?
- What is a gene?
- How do genes direct the production of proteins?
- How can gene mutations affect health and development?
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding C8B?
bacteria ; complement proteins ; cytosine ; deficiency ; DNA ; exon ; gene ; immune response ;immune system ; immunodeficiency ; infection ; inflammation ; nucleotide ; protein ; subunit ;thymine
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (8 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