TPMT Genotyping

Thiopurine methyltransferase (TPMT) is an enzyme that metabolises thiopurine drugs such as Azathioprine (AZA), 6-mercaptopurine (6-MP), and thioguanine (TG). These drugs are used to suppress the immune system and are prescribed to treat various diseases including hematologic malignancies, inflammatory bowel disease (IBD), rheumatoid arthritis, and as immunosuppressants in solid organ transplants.

TPMT displays genetic polymorphism resulting in null or decreased enzyme activity. At least 20 polymorphisms have been identified, of which, TPMT *2, *3A, *3B, *3C, and *4 are the most commonly studied.This genetic test identifies individual genetic differences associated with risk for thiopurine toxicity.