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Genetics Home Reference: your guide to understanding genetic conditions
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Carbamoyl phosphate synthetase I deficiency

Reviewed August 2006

What is carbamoyl phosphate synthetase I deficiency?

Carbamoyl phosphate synthetase I deficiency is an inherited disorder that causes ammonia to accumulate in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The nervous system is especially sensitive to the effects of excess ammonia.

Carbamoyl phosphate synthetase I deficiency often becomes evident in the first few days of life. An infant with this condition may be lacking in energy (lethargic) or unwilling to eat, and have a poorly controlled breathing rate or body temperature. Some babies with this disorder may experience seizures or unusual body movements, or go into a coma. Complications of carbamoyl phosphate synthetase I deficiency may include developmental delay and intellectual disability.

In some affected individuals, signs and symptoms of carbamoyl phosphate synthetase I deficiency may be less severe, and may not appear until later in life.

How common is carbamoyl phosphate synthetase I deficiency?

Carbamoyl phosphate synthetase I deficiency is a rare disorder; its overall incidence is unknown. Researchers in Japan have estimated that it occurs in 1 in 800,000 newborns in that country.

What genes are related to carbamoyl phosphate synthetase I deficiency?

Mutations in the CPS1 gene cause carbamoyl phosphate synthetase I deficiency.

Carbamoyl phosphate synthetase I deficiency belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of reactions that occurs in liver cells. This cycle processes excess nitrogen, generated when protein is used by the body, to make a compound called urea that is excreted by the kidneys.

In carbamoyl phosphate synthetase I deficiency, the enzyme that regulates the urea cycle is damaged or missing. The urea cycle cannot proceed normally, and nitrogen accumulates in the bloodstream in the form of ammonia. Ammonia is especially damaging to the nervous system, and excess ammonia causes neurological problems and other signs and symptoms of carbamoyl phosphate synthetase I deficiency.

Related Gene(s)

Changes in this gene are associated with carbamoyl phosphate synthetase I deficiency.

  • CPS1

How do people inherit carbamoyl phosphate synthetase I deficiency?

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Where can I find information about diagnosis or management of carbamoyl phosphate synthetase I deficiency?

These resources address the diagnosis or management of carbamoyl phosphate synthetase I deficiency and may include treatment providers.

  • Gene Review: Urea Cycle Disorders (http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=ucd-overview)
  • Gene Tests: Carbamoylphosphate Synthetase I Deficiency (http://www.ncbi.nlm.nih.gov/sites/GeneTests/lab/clinical_disease_id/2247)
  • MedlinePlus Encyclopedia: Hereditary urea cycle abnormality (http://www.nlm.nih.gov/medlineplus/ency/article/000372.htm)

You might also find information on the diagnosis or management of carbamoyl phosphate synthetase I deficiency in Educational resources (http://ghr.nlm.nih.gov/condition/carbamoyl-phosphate-synthetase-i-deficiency/show/Educational+resources) and Patient support (http://ghr.nlm.nih.gov/condition/carbamoyl-phosphate-synthetase-i-deficiency/show/Patient+support).

General information about the diagnosis (http://ghr.nlm.nih.gov/handbook/consult/diagnosis) and management (http://ghr.nlm.nih.gov/handbook/consult/treatment) of genetic conditions is available in the Handbook.

To locate a healthcare provider, see How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

Where can I find additional information about carbamoyl phosphate synthetase I deficiency?

You may find the following resources about carbamoyl phosphate synthetase I deficiency helpful. These materials are written for the general public.

  • MedlinePlus - Health information

    • Encyclopedia: Hereditary urea cycle abnormality (http://www.nlm.nih.gov/medlineplus/ency/article/000372.htm)
    • Health Topic: Metabolic Disorders (http://www.nlm.nih.gov/medlineplus/metabolicdisorders.html)
    • Health Topic: Newborn Screening (http://www.nlm.nih.gov/medlineplus/newbornscreening.html)
  • Genetic and Rare Diseases Information Center - Information about genetic conditions and rare diseases (http://rarediseases.info.nih.gov/GARD/Disease.aspx?PageID=4&DiseaseID=7269)

  • Educational resources - Information pages

    • Madisons Foundation (http://www.madisonsfoundation.org/index.php?option=com_mpower&task=disease&diseaseID=441)
    • Orphanet (http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=147)

  • Patient support - For patients and families

    • Children Living with Inherited Metabolic Diseases (http://www.climb.org.uk/)
    • National Organization for Rare Disorders (http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/307/viewAbstract)
    • National Urea Cycle Disorders Foundation (http://www.nucdf.org/)
    • Urea Cycle Disorders Consortium (http://rarediseasesnetwork.epi.usf.edu/ucdc/learnmore/definitions.htm)

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

  • Gene Reviews - Clinical summary (http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=ucd-overview)
  • Gene Tests - Genetic tests ordered by healthcare professionals (http://www.ncbi.nlm.nih.gov/sites/GeneTests/lab/clinical_disease_id/2247)
  • ClinicalTrials.gov - Linking patients to medical research (http://clinicaltrials.gov/ct2/results?cond=%22carbamoyl%20phosphate%20synthetase%20I%20deficiency%22%20OR%20%22Carbamoyl-Phosphate%20Synthase%20I%20Deficiency%20Disease%22)
  • PubMed - Recent literature (http://www.ncbi.nlm.nih.gov/pubmed?term=(Carbamoyl-Phosphate%20Synthase%20I%20Deficiency%20Disease%5BMAJR%5D)%20AND%20(carbamoyl%20phosphate%20synthetase%20I%20deficiency%5BTIAB%5D)%20AND%20english%5Bla%5D%20AND%20human%5Bmh%5D%20AND%20%22last%203600%20days%22%5Bdp%5D)
  • OMIM - Genetic disorder catalog (http://omim.org/entry/237300)

What other names do people use for carbamoyl phosphate synthetase I deficiency?

  • Carbamoyl-Phosphate Synthase I Deficiency Disease
  • Carbamyl-Phosphate Synthetase I Deficiency Disease

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines (http://ghr.nlm.nih.gov/ConditionNameGuide) and How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What if I still have specific questions about carbamoyl phosphate synthetase I deficiency?

Ask the Genetic and Rare Diseases Information Center (http://rarediseases.info.nih.gov/GARD/).

What glossary definitions help with understanding carbamoyl phosphate synthetase I deficiency?

ammonia ; autosomal ; autosomal recessive ; cell ; class ; coma ; complication ; compound ; deficiency ; developmental delay ; enzyme ; gene ; hyperammonemia ; incidence ; kidney ; lacking in energy ; lethargic ; mutation ; nervous system ; neurological ; newborn screening ; phosphate ; protein ; recessive ; screening ; seizure ; sign ; symptom ; synthetases ; toxic ; urea

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://ghr.nlm.nih.gov/glossary).

References

  • 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. (http://www.ncbi.nlm.nih.gov/pubmed/11536261?dopt=Abstract)
  • Endo F, Matsuura T, Yanagita K, Matsuda I. Clinical manifestations of inborn errors of the urea cycle and related metabolic disorders during childhood. J Nutr. 2004 Jun;134(6 Suppl):1605S-1609S; discussion 1630S-1632S, 1667S-1672S. Review. (http://www.ncbi.nlm.nih.gov/pubmed/15173438?dopt=Abstract)
  • 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. (http://www.ncbi.nlm.nih.gov/pubmed/9711878?dopt=Abstract)
  • Gene Review: Urea Cycle Disorders (http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=ucd-overview)
  • 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. (http://www.ncbi.nlm.nih.gov/pubmed/12655559?dopt=Abstract)
  • OMIM: CARBAMOYL PHOSPHATE SYNTHETASE I DEFICIENCY, HYPERAMMONEMIA DUE TO (http://omim.org/entry/237300)
  • 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. (http://www.ncbi.nlm.nih.gov/pubmed/11388595?dopt=Abstract)
  • Urea Cycle Disorders Consortium (http://rarediseasesnetwork.epi.usf.edu/ucdc/learnmore/definitions.htm)
  • 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. (http://www.ncbi.nlm.nih.gov/pubmed/15617192?dopt=Abstract)

 

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? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

 
Reviewed: August 2006
Published: February 18, 2013