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


Reviewed February 2013

What is the official name of the CPS1 gene?

The official name of this gene is “carbamoyl-phosphate synthase 1.”

CPS1 is the gene's official symbol. The CPS1 gene is also known by other names, listed below.

What is the normal function of the CPS1 gene?

The CPS1 gene provides instructions for making the enzyme carbamoyl phosphate synthetase I. This enzyme participates in the urea cycle, a series of reactions that occurs in liver cells. The urea cycle processes excess nitrogen, generated when protein is used by the body, into a compound called urea that is excreted by the kidneys. Excreting the excess nitrogen prevents it from accumulating in the form of ammonia, which is toxic.

The specific role of carbamoyl phosphate synthetase I is to control the first step of the urea cycle, a reaction in which excess nitrogen compounds are incorporated into the cycle to be processed.

How are changes in the CPS1 gene related to health conditions?

carbamoyl phosphate synthetase I deficiency - caused by mutations in the CPS1 gene

Approximately 10 mutations that cause carbamoyl phosphate synthetase I deficiency have been identified in the CPS1 gene. A mutated CPS1 gene may result in a carbamoyl phosphate synthetase I enzyme that is shorter than normal or the wrong shape, or may prevent the enzyme from being produced at all.

The shape of an enzyme affects its ability to control a chemical reaction. If the carbamoyl phosphate synthetase enzyme is misshapen or missing, it cannot fulfill its role in the urea cycle. Excess nitrogen is not converted to urea for excretion, and ammonia accumulates in the body. Ammonia is toxic, especially to the nervous system, so this accumulation causes neurological problems and other signs and symptoms of carbamoyl phosphate synthetase I deficiency.

other disorders - increased risk from variations of the CPS1 gene

One common alteration (polymorphism) in the CPS1 gene has been associated with increased risk of circulatory problems in newborns and in individuals who have received bone marrow transplants. This genetic change results in the amino acid (protein building block) asparagine being substituted for the amino acid threonine at position 1405 in the protein sequence (written as Thr1405Asn or T1405N).

Researchers believe that this polymorphism in the CPS1 gene may reduce the production of a compound called nitric oxide (NO). Normally, nitric oxide causes blood vessels to expand (dilate), which reduces blood pressure. A reduced amount of nitric oxide could lead to circulatory problems.

Where is the CPS1 gene located?

Cytogenetic Location: 2q35

Molecular Location on chromosome 2: base pairs 210,477,682 to 210,679,107

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

The CPS1 gene is located on the long (q) arm of chromosome 2 at position 35.

The CPS1 gene is located on the long (q) arm of chromosome 2 at position 35.

More precisely, the CPS1 gene is located from base pair 210,477,682 to base pair 210,679,107 on chromosome 2.

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

Where can I find additional information about CPS1?

You and your healthcare professional may find the following resources about CPS1 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 CPS1 gene or gene products?

  • carbamoyl-phosphate synthase 1, mitochondrial
  • carbamoyl phosphate synthase I
  • carbamoyl-phosphate synthase, mitochondrial precursor
  • carbamoylphosphate synthetase I
  • CPSase I

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

What glossary definitions help with understanding CPS1?

amino acid ; ammonia ; asparagine ; bone marrow ; compound ; deficiency ; enzyme ; excretion ; gene ; nervous system ; neurological ; phosphate ; polymorphism ; precursor ; protein ; protein sequence ; threonine ; toxic ; urea

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


  • Aoshima T, Kajita M, Sekido Y, Mimura S, Itakura A, Yasuda I, Saheki T, Watanabe K, Shimokata K, Niwa T. Carbamoyl phosphate synthetase I deficiency: molecular genetic findings and prenatal diagnosis. Prenat Diagn. 2001 Aug;21(8):634-7. (
  • Finckh U, Kohlschütter A, Schäfer H, Sperhake K, Colombo JP, Gal A. Prenatal diagnosis of carbamoyl phosphate synthetase I deficiency by identification of a missense mutation in CPS1. Hum Mutat. 1998;12(3):206-11. (
  • Funghini S, Donati MA, Pasquini E, Zammarchi E, Morrone A. Structural organization of the human carbamyl phosphate synthetase I gene (CPS1) and identification of two novel genetic lesions. Hum Mutat. 2003 Oct;22(4):340-1. (
  • Häberle J, Schmidt E, Pauli S, Rapp B, Christensen E, Wermuth B, Koch HG. Gene structure of human carbamylphosphate synthetase 1 and novel mutations in patients with neonatal onset. Hum Mutat. 2003 Apr;21(4):444. (
  • NCBI Gene (
  • Pearson DL, Dawling S, Walsh WF, Haines JL, Christman BW, Bazyk A, Scott N, Summar ML. Neonatal pulmonary hypertension--urea-cycle intermediates, nitric oxide production, and carbamoyl-phosphate synthetase function. N Engl J Med. 2001 Jun 14;344(24):1832-8. (
  • Rapp B, Häberle J, Linnebank M, Wermuth B, Marquardt T, Harms E, Koch HG. Genetic analysis of carbamoylphosphate synthetase I and ornithine transcarbamylase deficiency using fibroblasts. Eur J Pediatr. 2001 May;160(5):283-7. (
  • Summar ML, Gainer JV, Pretorius M, Malave H, Harris S, Hall LD, Weisberg A, Vaughan DE, Christman BW, Brown NJ. Relationship between carbamoyl-phosphate synthetase genotype and systemic vascular function. Hypertension. 2004 Feb;43(2):186-91. Epub 2004 Jan 12. (
  • Summar ML, Hall LD, Eeds AM, Hutcheson HB, Kuo AN, Willis AS, Rubio V, Arvin MK, Schofield JP, Dawson EP. Characterization of genomic structure and polymorphisms in the human carbamyl phosphate synthetase I gene. Gene. 2003 Jun 5;311:51-7. (
  • Wakutani Y, Nakayasu H, Takeshima T, Adachi M, Kawataki M, Kihira K, Sawada H, Bonno M, Yamamoto H, Nakashima K. Mutational analysis of carbamoylphosphate synthetase I deficiency in three Japanese patients. J Inherit Metab Dis. 2004;27(6):787-8. (


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: February 2013
Published: February 8, 2016