Thiopurine S-methyltransferase (TPMT) is a cytoplasmic enzyme involved in the metabolism of thiopurine drugs and its activity is largely influenced by polymorphisms of the TPMT gene. To date, more than 35 TPMT variants are known to be associated with reduced enzyme activity, but most studies on the TPMT genotype have included only common nonfunctional variants, such as TPMT*2 and TPMT*3. In this study, we carried out a complete sequencing analysis to screen all TPMT variants in Korean patients. A total of 900 Korean patients were genotyped for TPMT and 30 patients (3.3%) had the known TPMT variant alleles. TPMT*3C was found in 25 patients (2.8%): 24 patients with TPMT*1/*3 and one with TPMT*3/*3. Rare TPMT variants including TPMT*6, TPMT*16, and TPMT*32 were detected in five patients (0.6%) and a novel variant, TPMT*38 (c.514T>C, p.S172P), was identified in two patients. This is the first complete sequence-based screening study evaluating all TPMT variants in Asian populations.
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Departments of aLaboratory Medicine and Genetics
dClinical Pharmacology and Therapeutics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
* Hyun-Young Kim and Soo Hyun Lee contributed equally to the writing of this article.
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Correspondence to Soo-Youn Lee, MD, PhD, Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 135-710, Korea Tel: +82 2 3410 1834; fax: +82 2 3410 2719; e-mail: firstname.lastname@example.orgCorrespondence to Hong Hoe Koo, MD, PhD, Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 135-710, Korea Tel: +82 2 3410 3524; fax: +82 2 3410 0043; e-mail: email@example.com
Received July 27, 2014
Accepted December 1, 2014