NeuroSURE® Metabolites: Thymidine Phosphorylase Enzyme Analysis (Blood)

CPT: 82657

Special Instructions

This assay is not currently available in New York state.


Expected Turnaround Time

14 - 21 days


Specimen Requirements


Specimen

Whole blood-ACD


Volume

5 mL


Container

Yellow-top (ACD) tube


Storage Instructions

Ship within 24 hours.


Causes for Rejection

Hemolyzed sample; incorrect collection tube; received frozen


Test Details


Use

Thymidine phosphorylase Enzyme Analysis is used for the diagnosis of Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). Thymidine phosphorylase Enzyme Analysis may also be used for assessment of Variants of Uncertain Significance (VUS) identified during genetic testing (e.g. Next Generation Sequencing or Capillary Sequencung testing). MNGIE is an autosomal recessive disorder caused by mutations in the gene encoding thymidine phosphorylase (TP). The disease is characterized clinically by impaired eye movements, gastrointestinal dysmotility, cachexia, peripherl neuropathy, myopathy, and leukoencephalopathy. Molecular genetic studies of MNGIE patients' tissues have reveled mutlitple deletions, depletion, and site-specific point mutations of mitochondrial DNA. TP is a cytosolic enzyme required for nucleoside homeostasis. In MNGIE, TP activity is severely reduced and consequently levels of thymidine and deoxyuridine in plasma are drmatically elevated. MNGIE may benefit from hematopoietic stem cell transplantation.


Limitations

This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.


Methodology

High-pressure liquid chromatography (HPLC)


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