Carbamoylphosphate syntetase 1 (CPS1) deficiency


Carbamoylphosphate synthetase 1 deficiency (MIM 237300) is a rare autosomal recessive metabolic disorder. CPS1 deficiency affects the first enzymatic step in the urea cycle and results in hyperammonemia that can lead to lethargy, vomiting, coma and premature death. The clinical presentation is varied from neonatal onset, where patients have severe hyperammonemia which is fatal in the first few days of life, to a case reported where a woman in her third decade of life collapsed and died after a normal pregnancy and delivery. The onset of CPS1 may also be exacerbated by infection, metabolic stress or excessive protein intake. The CPS1 gene (2q35) consists of 38 exons.

Request a test

When requesting this test please use the referral form provided. Please also refer to any additional information provided for this test.

Additional information

Prior to genetic analysis, clinically affected patients should wherever possible be confirmed as having CPS1 deficiency by enzyme analysis on a liver biopsy. Linkage analysis may be requested in the affected proband of a family, please supply details of biochemical testing undertaken, clinical details and any relevant pedigree. Linkage analysis can be offered to the siblings for diagnostic testing and to adult relatives for carrier testing of CPS1 patients once an informative haplotype has been identified.

Sending address

Rare & Inherited Disease Laboratory
London North Genomic Laboratory Hub
Great Ormond Street Hospital for Children
Levels 4-6 Barclay House
37 Queen Square

Laboratory service


Sample requirements

1ml EDTA neonates, 5ml EDTA adults

Reference range

Not applicable

Turnaround time

20 days

Disease / group



Upon request

Call in advance?

Prenatals must be arranged in advance, through a Clinical Genetics department if possible.


The Genetics Laboratories provide an extensive range of Cytogenetics and Molecular Genetics diagnostic testing services.

© 2011 Great Ormond Street Hospital for Children NHS Trust