TPMT
Thiopurine S-Methyltransferase
What it does
Metabolizes thiopurines (azathioprine, 6-mercaptopurine, thioguanine).
Why this matters for Black patients
TPMT *3C is more common in African ancestry; carriers have severe myelosuppression with standard thiopurine doses. CPIC mandates dose reduction or alternative therapy.
Common variants
| Variant | Phenotype | African | European |
|---|---|---|---|
| *3C | Decreased function | 0.040 | 0.005 |
Note: This page is reference information, not medical advice. Pharmacogenomic differences are about ancestry, not race; race is an imperfect proxy. Discuss any medication changes with your prescriber.