rs1142345 TPMT
Normal TPMT function at *3C position.
What is rs1142345?
rs1142345 is a single-nucleotide polymorphism (SNP) in the TPMT gene (Thiopurine S-methyltransferase). Each person carries two copies, one from each parent, so a result is reported as a pair of letters such as AA. The table below describes what studies associate with each genotype; the association is statistical, across populations, and is not a diagnosis.
What does each rs1142345 genotype mean?
| Genotype | Association | What the evidence says | Confidence |
|---|---|---|---|
| AA | typical | Normal TPMT function at *3C position. | 95% |
| AC | increased | TPMT *3C carrier. Intermediate metabolizer. Reduced thiopurine dose recommended. | 95% |
| CC | increased | TPMT *3C homozygous. Poor metabolizer. Severely reduced thiopurine clearance. | 95% |
Which drugs have annotations for rs1142345?
PharmGKB clinical annotations (level 1A is the strongest evidence, 4 the weakest):
| Drug | Annotation type | Evidence level |
|---|---|---|
| cisplatin | Efficacy, Dosage, Toxicity, Metabolism/PK | 3 |
| cyclophosphamide | Efficacy, Dosage, Toxicity, Metabolism/PK | 3 |
| mercaptopurine | Efficacy, Dosage | 3 |
Is rs1142345 on 23andMe and AncestryDNA chips?
Chip coverage is not recorded for this variant. Orviva reports it when a raw-data file contains it directly or via a well-correlated proxy SNP, and says so when it does not.
Sources
- PharmGKB:3
- Drug:cisplatin
- Type:Efficacy
Upload your 23andMe, AncestryDNA or WeGene raw file → · Ask G2: “What is my genotype at rs1142345 and what does it mean for me?”
Genetic associations describe risk across populations, not a diagnosis for any one person. Most variants shift risk modestly and act alongside lifestyle, environment and other genes. Consumer DNA chips do not read every position and can be wrong at any single one. For general education only; talk to a clinician or genetic counsellor before acting on anything here, and never change a prescribed medicine without your prescriber.