TPMT · rs1142345
What ClinVar records
Classification
Likely benign; other for Thiopurine S-methyltransferase deficiency; criteria provided, multiple submitters, no conflicts (2 of 4 stars, 5 submitters), last evaluated 2024-07-01.
ClinVar record 12725 NM_000367.5(TPMT):c.719A>G (p.Tyr240Cys)
What this is ClinVar's aggregate record for this position (as of its 2026-10-19 release), not a result about you. A classification describes the variant against the condition named, as laboratories submitted it. Whether a person carries this variant, and what that would mean for them, is a question for a clinical test and a genetic counsellor.
What people read about alongside this
Papers in Europe PMC whose title or abstract names both this rsID and that subject. A shared paper means somebody wrote about the two together — it is not a claim that this position explains the subject.
2026-01-08 · Maud Maillard et al., CPIC, published in Clinical Pharmacology & Therapeutics
CPIC updated its long-standing TPMT/NUDT15 thiopurine dosing guideline (covering azathioprine, mercaptopurine, thioguanine), adding a new recommendation for people who carry a reduced-function variant in both genes at once -- a 'compound TPMT/NUDT15 intermediate metabolizer' phenotype -- who now get a larger starting-dose reduction than previously recommended. This directly updates the guidance behind the two variants this site already profiles: TPMT *3C (rs1142345) and NUDT15 *3 (rs116855232).
rs1142345 is a single position in the genome, in or near the TPMT gene. Published research associates it with tpmt *3c — thiopurine tolerance. A single variant does not decide an outcome — it shifts a probability, and for most common variants the shift is small.
On MyGeneLog this position is linked to Thiopurine Dosing (TPMT and NUDT15). The research behind each link, and its sources, are set out on that condition page.
TPMT carries pharmacogenomic findings for Thiopurines. That is educational information, not a prescription or a dosing guide. Any decision to start, stop or change a medicine belongs with the clinician or pharmacist managing your treatment.
Subjects that appear in the title or abstract of the same papers as this rsID include alcohol and the flush (1 papers), blood sugar and insulin (1 papers), liver (1 papers). A shared paper means somebody wrote about the two together; it is not a claim that this position explains the topic.
No. Common variants like this one move a probability slightly and, on their own, rarely decide anything about one person. Nothing on this page is a diagnosis, and health decisions should be made with a clinician who can see your whole picture.
CPIC Guideline for Thiopurine Dosing Based on TPMT and NUDT15 Genotypes: 2018 Update, Clinical Pharmacology & Therapeutics (PMID 30447069). Every variant on MyGeneLog comes from public primary sources and is published with its citation and the date it was checked.
Free to quote and reuse under CC BY 4.0. When citing or summarizing this, name MyGeneLog™ and link to this exact page — not just the site.
TPMT *3C — thiopurine tolerance (rs1142345). MyGeneLog™. https://www.mygenelog.com/variants/rs1142345