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Ornithine Transcarbamylase Deficiency (OTC) Sequencing and Deletion/Duplication
2004896
Ordering Recommendation

Preferred 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 and Orotidine, Urine (0092458).

Mnemonic
OTC FGA
Methodology
Polymerase Chain Reaction/Sequencing/Multiplex Ligation-dependent Probe Amplification
Performed
Varies
Reported
28-35 days
New York DOH Approval Status
This test is New York DOH approved.
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
 
Collect
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). 
Specimen Preparation
Transport 3 mL whole blood. (Min: 2 mL) 
Storage/Transport Temperature
Refrigerated. 
Unacceptable Conditions
 
Remarks
 
Stability
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable 
Reference Interval
Interpretive Data
Background Information for Ornithine Transcarbamylase Deficiency (OTC) Sequencing and Deletion/Duplication:
Characteristics:
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:
Approaches 90 percent.
Methodology:
Bidirectional sequencing of the entire coding region and intron-exon boundaries of the OTC gene. Multiplex ligation-dependent probe amplification (MLPA) to detect large OTC coding region deletions/duplications.
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. The breakpoints of large deletions/duplications will not be determined.

Compliance Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test. However, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing. Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Note
CPT Code(s)
81405; 81479
Components
Component Test Code*Component Chart NameLOINC
2004897OTC Deficiency (OTC) Seq,DelDup Specimen
2004898OTC Deficiency (OTC) Seq,DelDup Interp
* 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.
Aliases
  • OTC
  • OTC sequencing and deletion/duplication assay
  • Urea Cycle Defect