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Li, V. CYP27B1 Gene. Encyclopedia. Available online: (accessed on 04 December 2023).
Li V. CYP27B1 Gene. Encyclopedia. Available at: Accessed December 04, 2023.
Li, Vivi. "CYP27B1 Gene" Encyclopedia, (accessed December 04, 2023).
Li, V.(2020, December 23). CYP27B1 Gene. In Encyclopedia.
Li, Vivi. "CYP27B1 Gene." Encyclopedia. Web. 23 December, 2020.
CYP27B1 Gene

Cytochrome P450 Family 27 Subfamily B Member 1: The CYP27B1 gene provides instructions for making an enzyme called 1-alpha-hydroxylase (1α-hydroxylase). 


1. Normal Function

This enzyme carries out the second of two reactions 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 exposure. 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 processes unrelated to bone and tooth formation.

2. Health Conditions Related to Genetic Changes

2.1 Vitamin D-Dependent Rickets

At least 70 mutations in the CYP27B1 gene have been found to cause vitamin D-dependent rickets type 1A (VDDR1A), 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 abnormally curved (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 control mineral absorption. The resulting reduction in calcium and phosphate absorption from the intestines into the blood means there is less of these minerals to be deposited in developing bones (bone mineralization), which leads to soft, weak bones and other features of VDDR1A. Hypocalcemia also causes muscle weakness and seizures in some affected individuals.

3. Other Names for This Gene

  • 1alpha(OH)ase

  • 25 hydroxyvitamin D3-1-alpha hydroxylase

  • 25-hydroxyvitamin D-1 alpha hydroxylase, mitochondrial

  • 25-OHD-1 alpha-hydroxylase

  • CYP1alpha

  • CYP27B

  • cytochrome p450 27B1

  • cytochrome P450 subfamily XXVIIB polypeptide 1

  • cytochrome P450, family 27, subfamily B, polypeptide 1

  • cytochrome P450C1 alpha

  • cytochrome P450VD1-alpha

  • P450c1

  • VD3 1A hydroxylase


  1. Demir K, Kattan WE, Zou M, Durmaz E, BinEssa H, Nalbantoğlu Ö, Al-Rijjal RA,Meyer B, Özkan B, Shi Y. Novel CYP27B1 Gene Mutations in Patients with VitaminD-Dependent Rickets Type 1A. PLoS One. 2015 Jul 1;10(7):e0131376. doi:10.1371/journal.pone.0131376.
  2. Durmaz E, Zou M, Al-Rijjal RA, Bircan I, Akçurin S, Meyer B, Shi Y. Clinicaland genetic analysis of patients with vitamin D-dependent rickets type 1A. ClinEndocrinol (Oxf). 2012 Sep;77(3):363-9. doi: 10.1111/j.1365-2265.2012.04394.x.
  3. Kim CJ, Kaplan LE, Perwad F, Huang N, Sharma A, Choi Y, Miller WL, Portale AA.Vitamin D 1alpha-hydroxylase gene mutations in patients with 1alpha-hydroxylasedeficiency. J Clin Endocrinol Metab. 2007 Aug;92(8):3177-82.
  4. Malloy PJ, Feldman D. Genetic disorders and defects in vitamin D action. RheumDis Clin North Am. 2012 Feb;38(1):93-106. doi: 10.1016/j.rdc.2012.03.009.
  5. Nebert DW, Wikvall K, Miller WL. Human cytochromes P450 in health and disease.Philos Trans R Soc Lond B Biol Sci. 2013 Jan 6;368(1612):20120431. doi:10.1098/rstb.2012.0431. Print 2013 Feb 19. Review.
  6. Portale AA, Miller WL. Human 25-hydroxyvitamin D-1alpha-hydroxylase: cloning, mutations, and gene expression. Pediatr Nephrol. 2000 Jul;14(7):620-5. Review.
  7. Ryan JW, Anderson PH, Turner AG, Morris HA. Vitamin D activities and metabolicbone disease. Clin Chim Acta. 2013 Oct 21;425:148-52. doi:10.1016/j.cca.2013.07.024.
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Update Date: 23 Dec 2020