| pubmed-article:8299312 | pubmed:abstractText | Thiopurine methyltransferase (TPMT) is a cytoplasmic enzyme that preferentially catalyzes the S-methylation of aromatic and heterocyclic sulfhydryl compounds, including 6-mercaptopurine. TPMT exhibits genetic polymorphism in white populations, with 89% of individuals having high TPMT activity, 11% having intermediate activity, and one in 300 having extremely low or absent activity. TPMT activity is inversely correlated with formation of active 6-mercaptopurine metabolites (thioguanine nucleotides), thereby influencing 6-mercaptopurine toxicity and efficacy. | lld:pubmed |
