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Diseases Studied

The Rare Diseases Clinical Research Network is an NIH-funded research network of 20 active consortia or research groups working to advance treatment for diseases that are rare. Use the search tools on this page to find the diseases we currently study. You can reach out to the indicated consortia or research groups for more information on those diseases and studies underway.

This network focuses on clinical research and does not generally support clinical care outside of research activities. To learn about other rare diseases, please visit the Genetic and Rare Diseases Information Center (GARD), which is an NIH program that helps the public find reliable information about rare and genetic diseases. Their staff are specialists. Contact them at 1-888-205-2311 or email

All Diseases > Carbamyl phosphate synthetase deficiency

Carbamyl phosphate synthetase deficiency (CPS)

Alternative Names: CPS-I Deficiency

Disease Category: Urea Cycle Disorders

An inherited, metabolic, urea cycle disorder characterized by hyperammonemia (high blood ammonia levels) due to deficiency or absence of an enzyme needed to convert nitrogen from protein metabolism (break down) into urea (a waste product). Symptoms include vomiting, feeding and growth problems, fatigue, seizures, respiratory distress, cerebral edema (fluid accumulation around the brain), abnormal posturing and movements, coma, ataxia (lack of coordination), developmental delay, and intellectual disability.

Research groups studying this disease

Urea Cycle Disorders
UCDC logo

Urea Cycle Disorders Consortium (UCDC)


Long-term observation of the impact of UCDs on physical and neurological functioning, the relationship between health indicators and disease severity and the efficiency of UCD therapies.

Study of how UCDs affect thinking, body chemistry and brain structure using magnetic resonance imaging (MRI) and behavioral testing.

The purpose of this research is to determine if silent seizures (electrographic seizures) occur during a hyperammonemic (HA) episode in patients with urea cycle disorders (UCD). Urea cycle disorders lead to accumulation increased ammonia due to problems breaking down protein. The symptoms of UCD may present at birth, childhood or adulthood (milder deficiencies) and are associated with cognitive deficits, changes in behavior, brain swelling and seizures. Sometime the seizures are not clinically obvious, but can be picked up if a video recording and concurrent EEG (video EEG is used, cVEEG). cVEEG is used in many intensive care units across the country to pick up seizures. We want to determine if having seizures due to HA leads to any adverse cognitive outcomes, and want to use the EEG to identify any changes that may be associated with that.

We are doing this study to see how the results of two sets of tools used to measure developmental progress relate to one another and how acceptable completing each of these measures is to children and families of children with Urea Cycle Disorders. We are anxious to make longitudinal assessment (repeated observations over time) of cognition easier, quicker and more accessible for families of children with urea cycle disorders. In order to do so we want to understand the relationship between the 2 sets of measures.

Not Yet Recruiting

The purpose of this research study is to test a new method to measure food intake using smart phone photos of your food before and after meals. We will compare the smart phone food photos to a 3-day diet record and we will measure how many calories you burn.

Leads the fight to conquer urea cycle disorders (UCD) and drive critical research to improve outcomes while supporting families.