title: Validation of new allele-specific real-time PCR system for thiopurine methyltransferase genotyping in Korean population.
abstract: BACKGROUND
  Thiopurine drugs are metabolized via S-methylation and catalyzed by thiopurine S-methyltransferase (TPMT). Patients with very low TPMT activity are at high risk of fatal bone marrow toxicity when standard doses of thiopurine drugs are administered. TPMT genotyping can predict TPMT activity and is not affected by transfusion or red blood cell defects. Here, we report a new allele-specific real-time polymerase chain reaction (PCR) system for thiopurine methyltransferase genotyping that is validated in Korean population.
  
  
  METHODS
  Three major TPMT single-nucleotide polymorphisms (TPMT 2, 3B, and 3C) were genotyped using real-time PCR with the allele-specific primers and probes. Internal positive controls were included in each well, and an automatic interpretative algorithm was applied. This system was validated using 244 clinical samples and 2 commercial DNA samples that had been previously genotyped using PCR-direct sequencing. Results. All of the obtained results are concordant with those of the reference method. All of the internal positive control reactions were successful. The allele frequency of TPMT 3C was 2.05% (10 of 488 alleles). All of the patients with variant alleles were heterozygotes, and no homozygotes were detected. No TPMT 2, 3A, or 3B alleles were observed in this Korean population.
  
  
  CONCLUSIONS
  This rapid, accurate, and user-friendly genotyping system can be readily used to improve the efficacy and safety of thiopurine treatments in clinical practice.
authors.affiliation: Department of Laboratory Medicine, Ilsan Paik Hospital, Inje University College of Medicine, Joowha-ro 170, Ilsanseo-gu, Goyang, Gyeonggi, Republic of Korea.
authors.forename: Sollip
authors.initials: S
authors.lastname: Kim
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Lee
authors.forename: Woochang
authors.initials: W
authors.lastname: Lee
authors.forename: Sail
authors.initials: S
authors.lastname: Chun
authors.forename: Won-Ki
authors.initials: WK
authors.lastname: Min
mesh_terms: D000483:Alleles; D044466:Asian People; D005828:Genetics, Population; D060005:Genotyping Techniques; D006801:Humans; D007723:Korea; D008780:Methyltransferases / Q000235:genetics / Q000302:isolation & purification*; D020641:Polymorphism, Single Nucleotide; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*
chemical_list: D008780:Methyltransferases; C022745:thiopurine methyltransferase
references.citation: Clin Chim Acta. 2008 Dec;398(1-2):82-5
references.pmid: 18775689
references.citation: Clin Pharmacol Ther. 2011 Mar;89(3):387-91
references.pmid: 21270794
references.citation: Ann Intern Med. 1997 Apr 15;126(8):608-14
references.pmid: 9103127
references.citation: Pharmacogenomics. 2002 Jan;3(1):89-98
references.pmid: 11966406
references.citation: Br J Clin Pharmacol. 2001 Nov;52(5):539-46
references.pmid: 11736862
references.citation: Thromb Res. 2012 Jul;130(1):104-9
references.pmid: 21911247
references.citation: Eur J Clin Pharmacol. 2009 Mar;65(3):219-21
references.pmid: 19198820
references.citation: J Natl Cancer Inst. 1999 Dec 1;91(23):2001-8
references.pmid: 10580024
references.citation: Clin Chem. 2004 Feb;50(2):288-95
references.pmid: 14656901
references.citation: J Clin Pharmacol. 2013 Jan;53(1):67-74
references.pmid: 23400745
references.citation: Gastroenterology. 2000 Jun;118(6):1025-30
references.pmid: 10833476
references.citation: Clin Chem. 2008 Oct;54(10):1637-47
references.pmid: 18687736
references.citation: J Clin Oncol. 2001 Apr 15;19(8):2293-301
references.pmid: 11304783
references.citation: Ther Drug Monit. 2004 Apr;26(2):186-91
references.pmid: 15228163