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Thiopurine Methyltransferase (TPMT) Genotyping
- TPMT Genetic Testing
Detects the most common genotypes in approximately 95% of patients. Use is recommended prior to initiating thiopurine therapy.1
This assay will not detect approximately 5% of known deficiency mutations, and only the exons containing mutations in question are tested; polymorphisms or some sequence variants might affect efficiency of the PCR or mini-sequencing assays; assay does not distinguish between TPMT*1/3A heterozygote and the very rare compound heterozygote TPMT*3B/3C.
This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).
Polymerase chain reaction (PCR) and multiplex mini-sequencing
Whole blood or LabCorp buccal swab (buccal swab collection kit)
1 mL (Note: This volume does not allow for repeat testing).
Lavender-top (EDTA) tube, yellow-top (ACD) tube, green-top (heparin) tube, or LabCorp buccal swab (from kit)
Causes for Rejection
Frozen sample; hemolysis
Test orders for TPMT Genotyping must include an attestation that the provider has the patient's informed consent for genetic testing. See sample physician office consent form (Informed Consent for TPMT Genetic Testing) in Related Documents.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|504142||TPMT Genetic Test||504144||TPMT Genotype||41048-0|
|504142||TPMT Genetic Test||504145||TPMT Interpretation||62365-2|
|504142||TPMT Genetic Test||504146||TPMT Comment||77202-0|
|504142||TPMT Genetic Test||504143||Background||36922-3|