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Genes in the CYB gene family provide instructions for producing a group of proteins called cytochrome b proteins. In humans, the CYB gene family contains six functional genes and six pseudogenes (similar sequences of genetic material that do not provide instructions for making proteins). Cytochrome b proteins are produced in the immune system, brain, liver, and other tissues throughout the body. They play a role in various pathways that form new molecules by transferring negatively charged particles called electrons from one molecule to another. The new molecules that are formed are necessary for the pathway to continue.
The CYB gene family member expressed in the liver is important in the production of hemoglobin, which is the protein in red blood cells that carries oxygen to cells throughout the body. The cytochrome b protein produced in the brain plays a role in transmitting nerve signals between cells. The cytochrome b proteins produced in the immune system help fight off foreign invaders, such as bacteria and fungi.
Diseases caused by mutations in CYB genes usually occur because a key molecule in an important pathway is missing. The inability of the abnormal cytochrome b protein to transfer electrons leads to a shortage of the new molecule. A lack of this molecule disrupts the pathway and prevents it from moving forward. The features of the disease depend on the tissue where the protein is active. For example, mutations in the CYBB gene, which provides instruction for making a cytochrome b protein that is found in immune cells, lead to an immune deficiency disorder called chronic granulomatous disease. This condition results in an increased risk of developing infections caused by bacterial and fungal invaders.
The HUGO Gene Nomenclature Committee (HGNC) provides an index of gene families (http://www.genenames.org/cgi-bin/genefamilies/) and their member genes.
Genetics Home Reference summarizes the normal function and health implications of these members of the CYB gene family: CYBA, CYBB, and MT-CYB.
Genetics Home Reference includes these conditions related to genes in the CYB gene family:
bacteria ; charged particles ; chronic ; deficiency ; expressed ; gene ; granulomatous ; hemoglobin ; immune system ; molecule ; oxygen ; protein ; tissue
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (/glossary).
These sources were used to develop the Genetics Home Reference summary for the CYB gene family.
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.