What is TPMT mutation?

Thiopurine S-methyltransferase (TPMT) deficiency is a condition characterized by significantly reduced activity of an enzyme that helps the body process drugs called thiopurines. These drugs, which include 6-thioguanine, 6-mercaptopurine, and azathioprine, inhibit (suppress) the body’s immune system.

What is TPMT genetic test?

TPMT genetic test (genotype)—an alternative test to TPMT enzyme activity level is a genetic test that can identify genetic variations in the TPMT gene. This genetic test identifies individual genetic differences associated with risk for thiopurine toxicity. Each person has two copies of the TPMT gene.

Where is TPMT gene located?

chromosome 18q.
Thiopurine methyltransferase or thiopurine S-methyltransferase (TPMT) is an enzyme that in humans is encoded by the TPMT gene. A pseudogene for this locus is located on chromosome 18q. Chr.

How long does TPMT results take?

Test results will be ready in 2 business days.

What is the most common variant of TPMT?

In East Asian, African-American, and some African populations, the most common variant is TPMT*3C (~2%), although TPMT*8 may be more common in African populations than previously thought (~2%). In general, TPMT*2 occurs much less commonly, and TPMT*3B occurs rarely ( 14, 23 ).

What is the TPMT gene?

Learn more The TPMT gene provides instructions for making an enzyme called thiopurine S-methyltransferase (TPMT). This enzyme carries out a specific chemical reaction called S-methylation of a group of molecules known as aromatic and heterocyclic sulphydryl compounds.

What is the FDA recommendation for TPMT genotyping?

The FDA recommends TPMT genotyping or phenotyping before starting treatment with azathioprine. This allows patients who are at increased risk for toxicity to be identified and for the starting dose of azathioprine to be reduced, or for an alternative therapy to be used (1).

How do genetic polymorphisms influence TPMT and NUDT15 activity?

Genetic polymorphisms influence TPMT and NUDT15 activity. Several published studies indicate that patients with reduced TPMT or NUDT15 activity receiving usual doses of 6-MP or azathioprine, accumulate excessive cellular concentrations of active 6-TGNs, and are at higher risk for severe myelosuppression.