ARUP's Laboratory Test Directory

Ornithine Transcarbamylase Deficiency (OTC) Deletion/Duplication : 2004892
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Patient History for Ornithine Transcarbamylase Deficiency (OTC) Testing
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Additional Technical Information


Mnemonic: OTC DELDUP

Ordering Recommendation: Diagnostic testing for ornithine transcarbamylase deficiency. Carrier screening for ornithine transcarbamylase deficiency. Predictive testing for ornithine transcarbamylase deficiency.
Methodology: Polymerase Chain Reaction/Multiplex Ligation-dependent Probe Amplification
Performed: Varies
Reported: Within 14 days
Specimen Required: Collect: Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).

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

Storage/Transport Temperature: Refrigerated.

Stability (collection to initiation of testing): Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Interpretive Data: Background Information for Ornithine Transcarbamylase Deficiency (OTC) 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: Approximately 10 percent.
Methodology: Multiplex ligation-dependent probe amplification (MLPA) to detect large OTC coding region deletions/duplications.
Analytical Sensitivity and Specificity: 99 percent.
Limitations: Rare diagnostic errors can occur due to probe site mutations. Single base pair substitutions, small deletions/duplications, regulatory region mutations, and deep intronic mutations will not be detected. Large, single exon 1 deletions/duplications will not be detected. The breakpoints of large deletions/duplications will not be determined.



Counseling and informed consent are recommended for genetic testing. Consent forms are available online at www.aruplab.com.

See Compliance Statement C: www.aruplab.com/CS
CPT Code(s): 81479
Cross References: OTC (Ornithine Transcarbamylase Deficiency (OTC) Deletion/Duplication) , Urea Cycle Defect (Ornithine Transcarbamylase Deficiency (OTC) Deletion/Duplication)