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Reviewed August 2014

What is the official name of the CYP27B1 gene?

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

CYP27B1 is the gene's official symbol. The CYP27B1 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 CYP27B1 gene?

The CYP27B1 gene provides instructions for making an enzyme called 1-alpha-hydroxylase (1α-hydroxylase). This enzyme carries out the final reaction to convert vitamin D to its active form, 1,25-dihydroxyvitamin D3, also known as calcitriol. Vitamin D can be acquired from foods in the diet or can be made in the body with the help of sunlight. When active, this vitamin is involved in maintaining the proper balance of several minerals in the body, including calcium and phosphate, which are essential for the normal formation of bones and teeth. One of vitamin D's major roles is to control the absorption of calcium and phosphate from the intestines into the bloodstream. Vitamin D is also involved in several process unrelated to bone formation.

In order to carry out the roles of vitamin D, calcitriol attaches (binds) to another protein known as vitamin D receptor (VDR). The resulting calcitriol-VDR complex then binds to particular regions of DNA, known as vitamin D response elements, and regulates the activity of vitamin D-responsive genes. By turning the genes on or off, VDR helps control calcium and phosphate absorption and other processes.

Does the CYP27B1 gene share characteristics with other genes?

The CYP27B1 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 CYP27B1 gene related to health conditions?

vitamin D-dependent rickets - caused by mutations in the CYP27B1 gene

Mutations in the CYP27B1 gene cause vitamin D-dependent rickets type 1 (VDDR1), also known as vitamin D 1α-hydroxylase deficiency. This disorder of bone development is characterized by low levels of calcium (hypocalcemia) and phosphate (hypophosphatemia) in the blood, which lead to soft, weak bones that are prone to fracture. A common feature of this condition is bowed legs.

The CYP27B1 gene mutations that cause this condition reduce or eliminate the function of 1α-hydroxylase. As a result, vitamin D does not get converted to its active form and cannot stimulate the activity of genes important for mineral absorption. The lack of calcium and phosphate absorption from the intestines into the blood slows the deposition of these minerals in developing bones (bone mineralization), which leads to soft, weak bones and other features of VDDR1. Hypocalcemia also causes muscle weakness and seizures in some affected individuals.

Genetics Home Reference provides additional information about these conditions associated with changes in the CYP27B1 gene:

Where is the CYP27B1 gene located?

Cytogenetic Location: 12q14.1

Molecular Location on chromosome 12: base pairs 57,762,334 to 57,767,193

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

The CYP27B1 gene is located on the long (q) arm of chromosome 12 at position 14.1.

The CYP27B1 gene is located on the long (q) arm of chromosome 12 at position 14.1.

More precisely, the CYP27B1 gene is located from base pair 57,762,334 to base pair 57,767,193 on chromosome 12.

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

Where can I find additional information about CYP27B1?

You and your healthcare professional may find the following resources about CYP27B1 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 CYP27B1 gene or gene products?

  • 1alpha(OH)ase
  • 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial
  • 25 hydroxyvitamin D3-1-alpha hydroxylase
  • 25-OHD-1 alpha-hydroxylase
  • CYP1alpha
  • CYP27B
  • cytochrome p450 27B1
  • cytochrome P450C1 alpha
  • cytochrome P450, family 27, subfamily B, polypeptide 1
  • cytochrome P450 subfamily XXVIIB polypeptide 1
  • cytochrome P450VD1-alpha
  • P450c1
  • VD3 1A 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 CYP27B1?

autoimmune ; bone formation ; bone mineralization ; calcium ; cytochrome P450 ; deficiency ; DNA ; enzyme ; gene ; mineral ; OH ; phosphate ; protein ; receptor ; rickets ; sclerosis

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.

Reviewed: August 2014
Published: February 8, 2016