What is the official name of the CYP17A1 gene?
The official name of this gene is “cytochrome P450 family 17 subfamily A member 1.”
CYP17A1 is the gene's official symbol. The CYP17A1 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 CYP17A1 gene?
The CYP17A1 gene provides instructions for making a member of the cytochrome P450 enzyme family. Like other cytochrome P450 enzymes, CYP17A1 is involved in the formation (synthesis) of steroid hormones. This group of hormones includes sex hormones such as testosterone and estrogen, which are needed for normal sexual development and reproduction; mineralocorticoids, which help regulate the body's salt and water balance; and glucocorticoids, which are involved in maintaining blood sugar levels and regulating the body's response to stress.
Steroid hormones are synthesized through a series of chemical reactions. The CYP17A1 enzyme performs two important reactions in this process. The enzyme has 17 alpha(α)-hydroxylase activity, converting pregnenalone to 17-hydroxypregnenolone and progesterone to 17-hydroxyprogesterone. These hormone precursors are further processed to produce glucocorticoids and sex hormones. CYP17A1 also has 17,20-lyase activity, which converts 17-hydroxypregnenolone to dehydroepiandrosterone (DHEA). This reaction is integral to the production of sex hormones.
Does the CYP17A1 gene share characteristics with other genes?
The CYP17A1 gene belongs to a family of genes called CYP (cytochrome P450s).
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 CYP17A1 gene related to health conditions?
- 17 alpha-hydroxylase/17,20-lyase deficiency - caused by mutations in the CYP17A1 gene
- Dozens of mutations in the CYP17A1 gene have been found to cause 17α-hydroxylase/17,20-lyase deficiency. This condition affects the function of certain hormone-producing glands, leading to high blood pressure (hypertension) and abnormal sexual development. Mutations associated with this condition reduce or eliminate both 17α-hydroxylase and 17,20-lyase activity. Reduction of these activities leads to partial 17α-hydroxylase/17,20-lyase deficiency, while total loss of these activities leads to the more severe form of the disorder known as complete 17α-hydroxylase/17,20-lyase deficiency.Without 17α-hydroxylase activity, pregnenolone and progesterone are not converted to 17-hydroxypregnenolone or 17-hydroxyprogesterone, impairing production of glucocorticoids. Instead pregnenolone and progesterone are processed to form mineralocorticoids. An excess of these salt-regulating hormones leads to hypertension and low levels of potassium in the blood (hypokalemia).A loss of 17,20-lyase activity impairs sex hormone production. In females, a lack of female sex hormones disrupts development of internal reproductive organs (the ovaries and uterus) and secondary sex characteristics, such as breasts and menstrual periods. In chromosomal males (individuals with an X and a Y chromosome), a lack of male sex hormones leads to abnormal development of external genitalia. Depending on the severity of the condition, these affected individuals can have abnormal male genitalia, genitalia that do not look clearly male or clearly female (ambiguous genitalia), or characteristically female genitalia.
- other disorders - caused by mutations in the CYP17A1 gene
- A small number of CYP17A1 gene mutations have been found to cause isolated 17,20-lyase deficiency, which is characterized by abnormal sexual development without hypertension or hypokalemia. These mutations alter a region of the CYP17A1 protein that plays a role in the enzyme's 17,20-lyase function but not its 17α-hydroxylase function. As a result, 17,20-lyase activity is severely reduced but 17α-hydroxylase activity is normal. As in 17α-hydroxylase/17,20-lyase deficiency (described above), impairment of 17,20-lyase activity disrupts sex hormone production, leading to abnormal development of internal or external reproductive organs and delayed or absent puberty in affected individuals.
Where is the CYP17A1 gene located?
Cytogenetic Location: 10q24.3
Molecular Location on chromosome 10: base pairs 102,830,531 to 102,837,533
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The CYP17A1 gene is located on the long (q) arm of chromosome 10 at position 24.3.
More precisely, the CYP17A1 gene is located from base pair 102,830,531 to base pair 102,837,533 on chromosome 10.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about CYP17A1?
You and your healthcare professional may find the following resources about CYP17A1 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 CYP17A1 gene or gene products?
- 17-alpha-hydroxyprogesterone aldolase
- cytochrome P450 17A1
- cytochrome P450c17
- cytochrome P450-C17
- cytochrome P450, family 17, subfamily A, polypeptide 1
- cytochrome P450, subfamily XVII (steroid 17-alpha-hydroxylase), adrenal hyperplasia
- cytochrome p450 XVIIA1
- steroid 17-alpha-hydroxylase/17,20 lyase precursor
- steroid 17-alpha-monooxygenase
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 CYP17A1?
chromosome ; cytochrome P450 ; deficiency ; enzyme ; gene ; genitalia ; glucocorticoids ; hormone ;hyperplasia ; hypertension ; hypokalemia ; potassium ; precursor ; progesterone ; protein ; puberty ;reproduction ; sex hormone ; stress ; synthesis ; testosterone
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (6 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