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Carbamoyl phosphate synthetase I deficiency

(KAHR-bah-MOY-uhl • fAHs-fayt • SIN-thuh-tace • 1 • di-FISH-uhn-see)

General Condition Information

Other Names

  • Carbamoyl phosphate synthetase deficiency
  • Carbamoylphosphate synthetase deficiency
  • CPS
  • CPS I deficiency

Condition Type

Birth Prevalence

  • It is unknown how many babies are born with this rare condition each year in the United States.
  • Visit GeneReviews to learn more about how often this condition occurs.

Screening Finding

Low levels of citrulline

What is carbamoyl phosphate synthetase i deficiency

Carbamoyl phosphate synthetase I (CPS I) deficiency is an inherited (genetic) condition that prevents the body from removing ammonia properly. Ammonia is a waste product produced when the body breaks down protein.

CPS I is an enzyme that helps your body break down proteins. You need CPS I enzyme for a process called the urea cycle. The urea cycle helps remove ammonia from the body. The CPS I enzyme controls the first step in the urea cycle.

Without enough working CPS I enzyme, your baby has trouble breaking down proteins and getting rid of ammonia. High amounts of ammonia can damage your baby’s brain and body. If untreated, this damage leads to the signs and symptoms of the condition.

Newborn Screening and Follow-Up

Condition Details

Treatment and Management

It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.

Treatments may include the following:

Early and ongoing treatment can be lifesaving and can lead to better growth and development.

Date Last Reviewed: