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Reviewed March 2008

What is the official name of the CYP27A1 gene?

The official name of this gene is “cytochrome P450 family 27 subfamily A member 1.”

CYP27A1 is the gene's official symbol. The CYP27A1 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 CYP27A1 gene?

The CYP27A1 gene is a member of the cytochrome P450 gene family. Enzymes produced from the cytochrome P450 genes are involved in the formation and breakdown of various molecules and chemicals within cells. The CYP27A1 gene provides instructions for producing an enzyme called sterol 27-hydroxylase. This enzyme is located in the energy-producing centers of cells (mitochondria), where it is involved in the pathway that breaks down cholesterol to form acids used to digest fats (bile acids). Specifically, sterol 27-hydroxylase breaks down cholesterol to form a bile acid called chenodeoxycholic acid. The formation of bile acids from cholesterol is the body's main pathway for cholesterol removal. Sterol 27-hydroxylase plays a key role in maintaining normal cholesterol levels in the body.

Does the CYP27A1 gene share characteristics with other genes?

The CYP27A1 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 CYP27A1 gene related to health conditions?

cerebrotendinous xanthomatosis - caused by mutations in the CYP27A1 gene

More than 50 mutations that cause cerebrotendinous xanthomatosis have been identified in the CYP27A1 gene. Most of these mutations change one protein building block (amino acid) in the sterol 27-hydroxylase enzyme. The most common mutation changes the amino acid arginine to the amino acid cysteine at position 362 in the protein (written as Arg362Cys or R362C). Changes in amino acids typically disrupt the normal function of the protein and impair its ability to break down cholesterol. Other mutations cause no functional enzyme to be made. The reduction or lack of functional sterol 27-hydroxylase enzyme and subsequent accumulation of cholesterol throughout the body, particularly in the brain and tendons, cause the signs and symptoms of cerebrotendinous xanthomatosis.

Where is the CYP27A1 gene located?

Cytogenetic Location: 2q35

Molecular Location on chromosome 2: base pairs 218,781,749 to 218,815,293

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBIThis link leads to a site outside Genetics Home Reference.)

The CYP27A1 gene is located on the long (q) arm of chromosome 2 at position 35.

The CYP27A1 gene is located on the long (q) arm of chromosome 2 at position 35.

More precisely, the CYP27A1 gene is located from base pair 218,781,749 to base pair 218,815,293 on chromosome 2.

See How do geneticists indicate the location of a gene? in the Handbook.

Where can I find additional information about CYP27A1?

You and your healthcare professional may find the following resources about CYP27A1 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 CYP27A1 gene or gene products?

  • 5-beta-cholestane-3-alpha, 7-alpha, 12-alpha-triol 27-hydroxylase
  • CP27
  • CTX
  • CYP27
  • cytochrome P-450C27/25
  • cytochrome P450, family 27, subfamily A, polypeptide 1
  • cytochrome P450, subfamily XXVIIA (steroid 27-hydroxylase, cerebrotendinous xanthomatosis), polypeptide 1
  • sterol 27-hydroxylase
  • vitamin D(3) 25-hydroxylase

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 CYP27A1?

acids ; amino acid ; arginine ; bile ; breakdown ; cholesterol ; cysteine ; cytochrome P450 ; enzyme ; gene ; mitochondria ; mutation ; protein

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.

Reviewed: March 2008
Published: February 1, 2016