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TPMT

Thiopurine S-methyltransferase

Gene Number: 7172

Location: 6p22.3

Key Functions: Thiopurine metabolism, drug detoxification, TPMT enzymatic activity


The TPMT gene, located on chromosome 6p22.3, encodes thiopurine S-methyltransferase, a cytosolic enzyme that plays a pivotal role in the metabolism and detoxification of thiopurine drugs—a class of medications widely used in the treatment of leukemia, autoimmune diseases, and organ transplant rejection. This enzyme catalyzes the S-methylation of thiopurine compounds such as azathioprine, 6-mercaptopurine (6-MP), and thioguanine, converting them into inactive metabolites that are less cytotoxic.

SNP ID
Your Genotype
Alternative Alleles
Interpretation
rs1800460
Analyze your DNA to see your genotype
T
Analyze your DNA to see a personalized result.
rs1800460
  • CC – Normal TPMT activity; standard metabolizer (R).

  • TC – Reduced TPMT activity; impaired thiopurine metabolism (R).

  • TT – Reduced TPMT activity; impaired thiopurine metabolism (R).

Functional effect: The T allele (TPMT3B / part of 3A when combined with rs1142345 C) dramatically reduces enzyme function, increasing the risk of treatment-induced toxicity (R).


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