Description:
Carbamoyl phosphate synthetase I (EC 6.3.4.16) is the rate-limiting enzyme that catalyzes the first committed step of the hepatic urea cycle. The mitochondrial isozyme is designated CPS I and the cytoplasmic enzyme CPS II. CPS I catalyzes the conversion of ammonia and bicarbonate to carbamyl phosphate. The reaction requires a cofactor, N-acetylglutamate (NAG). Deficiency of CPS1 causes an autosomal recessive urea cycle disorder that is characterized by the triad of hyperammonemia, encephalopathy, and respiratory alkalosis. Two forms of carbamoyl phosphate synthetase deficiency are recognized: a lethal neonatal type and a less severe, delayed-onset type. CPS1 is located at chromosome 2q35. The gene contains 38 coding exons and encodes a polypeptide of 1500 amino acid. To date, 20 different mutations have been reported, most of thes are private mutations.

Reasons for Referral:

• Confirmation of a clinical diagnosis
• Carrier testing

Testing Methodology:
The exons and flanking intronic regions of the CPS1 gene are PCR amplified and sequenced in the forward and reverse directions.

Specimen Requirements:
Blood: EDTA (purple-top) tubes: Adult: 5 cc; Child & Infant: 3 cc

Turnaround Time: 5 weeks

CPT Codes and Prices:
Index: 83891, 83904x76, 83898x38, 83912, 83894x2
Known Familial Mutation: 83904x4, 83898x2, 83912, 83891, 83894x2

Shipping Information

Forms:
 >> Gene Sequencing Requisition or Mitochondrial Requisition - Mitochondrial Diagnostic Checklist is included
 >> Prenatal Requisition

Test Code:
Index: 3345
Known Familial Mutation: 3346
Prenatal: 3347

Last Modified: 5-2-08