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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed December 2007

What is the official name of the HPRT1 gene?

The official name of this gene is “hypoxanthine phosphoribosyltransferase 1.”

HPRT1 is the gene's official symbol. The HPRT1 gene is also known by other names, listed below.

What is the normal function of the HPRT1 gene?

The HPRT1 gene provides instructions for producing an enzyme called hypoxanthine phosphoribosyltransferase 1. This enzyme allows cells to recycle purines, a type of building block of DNA and its chemical cousin RNA. Manufacturing purines uses more energy and takes more time than recycling purines, which makes recycling these molecules more efficient. Recycling purines ensures that cells have a plentiful supply of building blocks for the production of DNA and RNA. The process of recycling purines is also known as the purine salvage pathway.

How are changes in the HPRT1 gene related to health conditions?

Lesch-Nyhan syndrome - caused by mutations in the HPRT1 gene

More than 200 mutations in the HPRT1 gene have been found to cause Lesch-Nyhan syndrome. These mutations include changes in single DNA building blocks (nucleotides) or insertions or deletions of small amounts of DNA within the gene. These changes result in either nonfunctional or very low-function hypoxanthine phosphoribosyltransferase 1. Under these conditions, uric acid, a waste product of purine breakdown, accumulates in the body and can cause gouty arthritis (arthritis caused by uric acid in the joints), kidney stones, and bladder stones. It is unclear how this enzyme deficiency causes the neurological and behavioral problems characteristic of Lesch-Nyhan syndrome.

other disorders - caused by mutations in the HPRT1 gene

Certain mutations in the HPRT1 gene can also cause a condition featuring gouty arthritis called HPRT-related gout, previously known as Kelley-Seegmiller syndrome. Individuals with this condition have lower than normal levels of hypoxanthine phosphoribosyltransferase 1. Kidney problems commonly occur in people with this condition because a buildup of uric acid crystals can form kidney stones. Rarely, this condition will cause problems with the nervous system.

Where is the HPRT1 gene located?

Cytogenetic Location: Xq26.1

Molecular Location on the X chromosome: base pairs 134,452,842 to 134,500,668

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The HPRT1 gene is located on the long (q) arm of the X chromosome at position 26.1.

The HPRT1 gene is located on the long (q) arm of the X chromosome at position 26.1.

More precisely, the HPRT1 gene is located from base pair 134,452,842 to base pair 134,500,668 on the X chromosome.

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

Where can I find additional information about HPRT1?

You and your healthcare professional may find the following resources about HPRT1 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 HPRT1 gene or gene products?

  • Guanine Phosphoribosyltransferase
  • HGPRTase
  • HOX5.4
  • HPRT
  • HPRTase
  • Hypoxanthine-Guanine Phosphoribosyltransferase
  • hypoxanthine phosphoribosyltransferase 1 (Lesch-Nyhan syndrome)
  • IMP Pyrophosphorylase

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding HPRT1?

arthritis ; breakdown ; deficiency ; DNA ; enzyme ; gene ; gout ; guanine ; kidney ; kidney stones ; nervous system ; neurological ; purines ; RNA ; syndrome ; uric acid

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Duan J, Nilsson L, Lambert B. Structural and functional analysis of mutations at the human hypoxanthine phosphoribosyl transferase (HPRT1) locus. Hum Mutat. 2004 Jun;23(6):599-611. (
  • Jinnah HA, De Gregorio L, Harris JC, Nyhan WL, O'Neill JP. The spectrum of inherited mutations causing HPRT deficiency: 75 new cases and a review of 196 previously reported cases. Mutat Res. 2000 Oct;463(3):309-26. Review. (
  • NCBI Gene (
  • Nyhan WL. Dopamine function in Lesch-Nyhan disease. Environ Health Perspect. 2000 Jun;108 Suppl 3:409-11. Review. (
  • Nyhan WL. The recognition of Lesch-Nyhan syndrome as an inborn error of purine metabolism. J Inherit Metab Dis. 1997 Jun;20(2):171-8. Review. (
  • Puig JG, Torres RJ, Mateos FA, Ramos TH, Arcas JM, Buño AS, O'Neill P. The spectrum of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency. Clinical experience based on 22 patients from 18 Spanish families. Medicine (Baltimore). 2001 Mar;80(2):102-12. (
  • Sculley DG, Dawson PA, Emmerson BT, Gordon RB. A review of the molecular basis of hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency. Hum Genet. 1992 Nov;90(3):195-207. Review. (


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: December 2007
Published: February 1, 2016