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, Urine (3000704).

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.

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.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

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

Compliance Category

Laboratory Developed Test (LDT)

Note

Hotline History

N/A

CPT Codes

81405; 81479

Components

Component Test Code* Component Chart Name LOINC
2004897 OTC Deficiency (OTC) Seq,DelDup Specimen 31208-2
2004898 OTC Deficiency (OTC) Seq,DelDup Interp 43233-6
* 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
Ornithine Transcarbamylase Deficiency (OTC) Sequencing and Deletion/Duplication