Reviewed July 2006
What is the official name of the CYP21A2 gene?
The official name of this gene is “cytochrome P450, family 21, subfamily A, polypeptide 2.”
CYP21A2 is the gene's official symbol. The CYP21A2 gene is also known by other names, listed below.
What is the normal function of the CYP21A2 gene?
The CYP21A2 gene provides instructions for making an enzyme called steroid 21-hydroxylase, which is part of the cytochrome P450 family of enzymes. Cytochrome P450 enzymes are involved in many processes in the body, such as assisting with reactions that break down drugs and helping to produce cholesterol, certain steroid hormones, and fats (lipids). Steroid 21-hydroxylase enables the adrenal glands, which are located on top of the kidneys, to convert cholesterol into other steroid hormones, specifically cortisol and aldosterone. Cortisol helps maintain blood sugar levels, protects the body from stress, and suppresses inflammation. Aldosterone, sometimes called the salt-retaining hormone, acts on the kidneys to regulate the levels of salt and water in the body, which affect blood pressure. Precursor molecules that are formed in the pathway leading to these two steroid hormones can be converted into male hormones called androgens. Androgens are normally responsible for the appearance of secondary sex characteristics in males (virilization).
Does the CYP21A2 gene share characteristics with other genes?
The CYP21A2 gene belongs to a family of genes called CYP (cytochrome P450).
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 CYP21A2 gene related to health conditions?
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21-hydroxylase deficiency - caused by mutations in the CYP21A2 gene
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Mutations in the CYP21A2 gene are often caused by exchanges of DNA between the CYP21A2 gene and a very similar but nonfunctional piece of DNA called a pseudogene. Some of these exchanges can produce large or small deletions of DNA within the CYP21A2 gene. Other mutations result in a change in the building blocks (amino acids) that make up the 21-hydroxylase enzyme. In some cases, rearrangements within the gene scramble the instructions for making the enzyme, leading to an altered version of steroid 21-hydroxylase.
Mutations that delete all or part of the gene are among the most serious and may result in the production of little or no enzyme. Other mutations lead to the production of an abnormally sized protein that may not be functional. These mutations are most often associated with the salt-loss type of 21-hydroxylase deficiency. Mutations that less severely affect the structure or production of the enzyme have variable effects on the level of enzyme activity. These mutations account for the classic virilizing and nonclassic types of 21-hydroxylase deficiency.
Where is the CYP21A2 gene located?
Cytogenetic Location: 6p21.3
Molecular Location on chromosome 6: base pairs 32,114,060 to 32,117,397
The CYP21A2 gene is located on the short (p) arm of chromosome 6 at position 21.3.
More precisely, the CYP21A2 gene is located from base pair 32,114,060 to base pair 32,117,397 on chromosome 6.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about CYP21A2?
What other names do people use for the CYP21A2 gene or gene products?
- CA21H
- CAH1
- CP21A_HUMAN
- CPS1
- CYP21
- CYP21B
- Cytochrome P450 Family 21 Subfamily A Polypeptide 2
- cytochrome P450, subfamily XXIA (steroid 21-hydroxylase, congenital adrenal hyperplasia), polypeptide 2
- Cytochrome P450 XXI
- Cytosteroid 21-Monooxygenase
- P450c21B
- steroid 21-hydroxylase
- steroid 21-monooxygenase
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 CYP21A2?
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.