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.

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