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The urea cycle is a metabolic process that is the main mechanism for clearance of excess nitrogen resulting from protein catabolism and the metabolism of nitrogenous compounds such as ATP from the cell.  It is also the only source for the endogenous production of arginine, citrulline, and ornithine.  The enzymes within the urea cycle, as well as an enzyme responsible for the production of a required cofactor, are the key components for this metabolic process. Detrimental effects occur when deleterious genetic defects occur within this process whose group of disorders are known as urea cycle disorders and can be categorized based on the specific enzyme deficiency that is present. Mutations in genes encoding the cellular machinery for this pathway can be clinically heterogeneous, but biochemical tests are carried out during newborn screening to assess sets of metabolic markers for urea cycle disorders. Patients may present with hypoglycemia, abnormality of liver, cardiomyopathy, and muscle weakness. These conditions are inherited in an autosomal recessive or X-linked manner.  This next-generation sequencing test targets the coding regions for 6 clinically significant genes associated with urea cycle disorders.

Reasons for Referral:

  • Confirmation of a clinical diagnosis
  • Carrier testing


Next generation sequencing will analyze the exons or coding regions of 6 urea cycle disorder associated genes using Illumina NextSeq 500 technology and preparing samples using hybridization probes to enrich exonic regions. Promoter, intronic, etc. regions are not assessed on our assay, but may contain variants that impact gene function.

Urea Cycle Disorders Panel (6 genes): ARG1, ASL, ASS1, CPS1, NAGS, OTC

Specimen Requirements:

Blood:  EDTA or ACD (Solution A or B):

  • Adult: 5 mL
  • Child: 5 mL
  • Infant: 2-3 mL

A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information, including ethnicity, clinical history, and family history.

Test Performed (Days):


Turn Around Time:

8 weeks

Shipment Sensitivity Requirements:

  • Package and ship specimen to remain cold, but not frozen. 
  • Ship via overnight express, using the FedEx priority overnight label provided. 
  • Contact Client Services for shipping kits and instructions at (855) 535-1522.


Additional Info:

The Knight Cancer Institute at Oregon Health & Science University is a pioneer in the field of precision cancer medicine. The institute's director, Brian Druker, M.D., helped prove it was possible to shut down just the cells that enable cancer to grow. This breakthrough has made once-fatal forms of the disease manageable and transformed how cancer is treated. The OHSU Knight Cancer Institute is the only National Cancer Institute-designated Cancer Center between Sacramento and Seattle – an honor earned only by the nation's top cancer centers. It is headquarters for one of the National Cancer Institute's largest research collaboratives, SWOG, in addition to offering the latest treatments and technologies as well as hundreds of research studies and clinical trials.

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