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Nomenclature for alleles of the thiopurine methyltransferase gene

Lookup NU author(s): Dr Sally Coulthard


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The drug-metabolizing enzyme thiopurine methyltransferase (TPMT) has become one of the best examples of pharmacogenomics to be translated into routine clinical practice. TPMT metabolizes the thiopurines 6-mercaptopurine, 6-thioguanine, and azathioprine, drugs that are widely used for treatment of acute leukemias, inflammatory bowel diseases, and other disorders of immune regulation. Since the discovery of genetic polymorphisms in the TPMT gene, many sequence variants that cause a decreased enzyme activity have been identified and characterized. Increasingly, to optimize dose, pretreatment determination of TPMT status before commencing thiopurine therapy is now routine in many countries. Novel TPMT sequence variants are currently numbered sequentially using PubMed as a source of information; however, this has caused some problems as exemplified by two instances in which authors' articles appeared on PubMed at the same time, resulting in the same allele numbers given to different polymorphisms. Hence, there is an urgent need to establish an order and consensus to the numbering of known and novel TPMT sequence variants. To address this problem, a TPMT nomenclature committee was formed in 2010, to define the nomenclature and numbering of novel variants for the TPMT gene. A website ( serves as a platform for this work. Researchers are encouraged to submit novel TPMT alleles to the committee for designation and reservation of unique allele numbers. The committee has decided to renumber two alleles: nucleotide position 106 (G>A) from TPMT*24 to TPMT*30 and position 611 (T>C, rs79901429) from TPMT*28 to TPMT*31. Nomenclature for all other known alleles remains unchanged. Pharmacogenetics and Genomics 23: 242-248 (C) 2013 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins. Pharmacogenetics and Genomics 2013, 23:242-248

Publication metadata

Author(s): Coulthard SA; Appell ML; Berg J; Duley J; Evans WE; Kennedy MA; Lennard L; Marinaki T; McLeod HL; Relling MV; Schaeffeler E; Schwab M; Weinshilboum R; Yeoh AEJ; McDonagh EM; Hebert JM; Klein TE

Publication type: Review

Publication status: Published

Journal: Pharmacogenetics and Genomics

Year: 2013

Volume: 23

Issue: 4

Pages: 242-248

Print publication date: 01/04/2013

ISSN (print): 1744-6872

ISSN (electronic): 1744-6880



DOI: 10.1097/FPC.0b013e32835f1cc0