Thiopurine Methyltransferase (TPMT) and Nudix Hydrolase (NUDT15) Genotyping, Varies
Use
This test is used to predict the potential for toxicity to thiopurine drugs—specifically 6‑mercaptopurine, 6‑thioguanine, and azathioprine—by genotyping the TPMT and NUDT15 genes, which are critical for thiopurine metabolism.
Special Instructions
Report may note gene regions unable to be interrogated when using saliva or extracted DNA sources; maternal cell contamination studies are recommended for umbilical cord blood specimens (order MATCC separately).
Limitations
Rare TPMT or NUDT15 variants not detected by this assay may lead to false-negative or false-positive results; if no variant alleles are detected, the most likely genotype is TPMT*1/*1 or NUDT15*1/*1, but rarer alleles may still be present. Donor DNA (from transfusions or hematopoietic stem cell transplant recipients) may interfere with results. This test does not detect all genetic variants in TPMT or NUDT15 and cannot distinguish TPMT*1/*3A from TPMT*3B/*3C. No equivalent activity assay exists for NUDT15.
New York Approved
Methodology
PCR-based (PCR)
Biomarkers
LOINC Codes
- 93193-1
- 41048-0
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
3 mL
Minimum Volume
Not provided
Container
Lavender top (EDTA)
Collection Instructions
Invert several times to mix blood. Send whole blood specimen in original tube. Do not aliquot.
Patient Preparation
A previous hematopoietic stem cell transplant from an allogenic donor will interfere with testing.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 days |
| Refrigerated | 4 days |
| Frozen | 4 days |