Thiopurine S-Methyltransferase

TPMT or TPMTD or Thiopurine S-Methyltransferase or Thiopurine Methyltransferase refers to either a gene or the enzyme encoded by it.

Function
TPMT has a role in the function of the immune system.

Thiopurine methyltransferase deficiency
TPMT deficiency is a genetic condition that means that the enzymes that help process thiopurine drugs have reduced activity. If people with TPMT deficiency take thiopurine drugs, they are at inceased risk of bone marrow damage.

Thiopurine genetic testing
TPMT genetic testing aims to improve climical outcomes and reduce harm in people with TPMT deficiency.

Drug responses
Thiopurines are relatively common drugs, but thiopurine methyltransferase deficiency studies have found that 1 in 300 people have no thiopurine methyltransferase enzyme activity, and 11% have reduced activity.

Thiopurines (drugs)
Thiopurine drugs suppress immune system, they include: Thiopurine drugs are used to treat:
 * 6-thioguanine
 * 6-mercaptopurine
 * azathioprine
 * Crohn's disease
 * Rheumatoid arthritis
 * certain other autoimmune diseases
 * some cancers, for example blood or immune cell cancers (leukemias, and lymphomas)
 * to help prevent the rejection of organ transplants after organ transplants

ME/CFS
Genetic studies of ME/CFS patients have not so far identified any TPMT genes as possibly associated with ME/CFS.

Thiopurine drugs have not been suggested as potentially useful for ME/CFS, and there is no guidance to avoid them. 

Learn more

 * TPMT gene - MedlinePlus
 * Thiopurine S-methyltransferase deficiency - MedlinePlus
 * Thiopurine S methyltranferase deficiency - Genetic and Rare Diseases Information Center
 * TPMT Gene - Gene cards