Carbamoyl Phosphate Synthetase I Deficiency

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Carbamoyl Phosphate Synthetase I Deficiency is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • carbamoylphosphatase deficiency I
  • carbamoyl phosphate synthetase deficiency
  • carbamylphosphatase deficiency I
  • carbamyl phosphate synthetase I
  • CPSI deficiency

Disorder Subdivisions

  • None

General Discussion

Carbamoyl phosphate synthetase I deficiency (CPSID) is a rare inherited disorder characterized by complete or partial lack of the carbamoyl phosphate synthetase (CPS) enzyme. This is one of five enzymes that play a role in the breakdown and removal of nitrogen from the body, a process known as the urea cycle. The lack of the CPSI enzyme results in excessive accumulation of nitrogen, in the form of ammonia (hyperammonemia), in the blood. Affected children may experience vomiting, refusal to eat, progressive lethargy, and coma. CPSID is inherited as an autosomal recessive genetic disorder.

The urea cycle disorders are a group of rare disorders affecting the urea cycle, a series of biochemical processes in which nitrogen is converted into urea and removed from the body through the urine. Nitrogen is a waste product of protein metabolism. Failure to break down nitrogen results in the abnormal accumulation of nitrogen, in the form of ammonia, in the blood.

Supporting Organizations

American Kidney Fund, Inc.

11921 Rockville Pike
Suite 300
Rockville, MD 20852
Tel: (800)638-8299

CLIMB (Children Living with Inherited Metabolic Diseases)

Climb Building
176 Nantwich Road
Crewe, CW2 6BG
United Kingdom
Tel: 4408452412173
Fax: 4408452412174

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311

NIH/National Institute of Diabetes, Digestive & Kidney Diseases

Office of Communications & Public Liaison
Bldg 31, Rm 9A06
Bethesda, MD 20892-2560
Tel: (301)496-3583

National Kidney Foundation

30 East 33rd Street
New York, NY 10016
Tel: (212)889-2210
Fax: (212)689-9261
Tel: (800)622-9010

National Urea Cycle Disorders Foundation

75 South Grand Avenue
Pasadena, CA 91105-1602
Tel: (626)578-0833
Fax: (626)578-0823
Tel: (800)386-8233

Urea Cycle Disorders Consortium

Children's National Medical Center
111 Michigan Avenue, NW
Washington, DC 20010
Tel: (815)333-4014

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated:  12/26/1969
Copyright  2011 National Organization for Rare Disorders, Inc.