Ordering Recommendation

Acceptable initial genetic test to confirm OTC deficiency, following suggestive clinical and laboratory findings. To diagnose or rule out OTC deficiency, refer to Amino Acids Quantitative by LC-MS/MS, Plasma (2009389), Organic Acids, Urine (0098389), and Orotic Acid, Urine (3000704).


Polymerase Chain Reaction/Sequencing




14-21 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation

Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature


Unacceptable Conditions

Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable

Reference Interval
Interpretive Data

Background Information for Ornithine Transcarbamylase Deficiency (OTC) Sequencing:
  Classic OTC deficiency is a urea cycle disorder characterized by hyperammonemia, cyclical vomiting, seizures, lethargy, coma and neonatal death if not treated. Clinical presentation varies widely in females, and some males can have non-classical forms.
Incidence: Approximately 1 in 20,000.
Inheritance: X-linked.
Penetrance: Variable depending on sex and mutation.
Cause: Pathogenic OTC gene mutations.
Clinical Sensitivity: Approximately 80 percent.
Methodology: Bidirectional sequencing of the entire OTC coding region and intron/exon boundaries.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations and deep intronic mutations will not be detected in individuals of both sexes; large deletions/duplications will not be detected in females.

Compliance Statement C: For human genetic inheritable conditions and mutations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Hotline History
CPT Codes


Component Test Code* Component Chart Name LOINC
2004902 OTC Deficiency (OTC) Seq Specimen
2004903 OTC Deficiency (OTC) Seq Interpretation
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • OTC Sequencing
  • Urea Cycle Defect
Ornithine Transcarbamylase Deficiency (OTC) Sequencing