The deficiency of thiopurine S-methyl transferase enzyme and determination of TPMT*2, *3B and *3C mutations in diyarbakir region

Thiopurine S-Methyltransferase is a cytoplasmic enzyme that catalyzes methylation of thiopurine drugs such as 6-mercaptopurine or azathioprine. The activity of TPMT is polymorphic and it has three types of enzyme activity. In populations; about 89% of people have high enzyme activiy, approximately 11% intermediate activity and 0,3% (1: 300) low or undetectable enzyme activity. When patients who have TPMT deficiency is treated with standart dose of thiopurine drugs, hematologic toxicity or the risk of mortality will be higher then normal enzyme activity. In researchs which was made in different populations have shown that there is a high relation between TPMT enzyme activity and genotype. The reason of TPMT deficiency is SNP(s) in TPMT gene. There are four common mutant allels. These are TPMT*2 (G238C), TPMT*3A (G460A and A719G), TPMT*3B (G460A) and TPMT*3C (A719G). These SNP?s(Single Nucleotide Polymorphsim) are major frequent mutations of TPMT. Before patients is treated with thiopurine drugs, determination of TPMT activity will be useful to avoid life-threatening complications.The aim of this study is to determine TPMT*2, *3B and *3C mutations in Diyarbakir region and to give information to clinicians about TPMT mutations.In this study, whool blood samples were obtained from patients randomly and DNA?s were isolated by using DNA purification kits. TPMT genotypes were determined by using Real Time PCR and TPMT mutation kits. 96 patients were evaluated. 2 of 96 patients were heterozygot TPMT*3B mutant allele and 2 of 96 patients were heterozygote TPMT*3C mutant allele.Key Words: TPMT genotypes, Real Time PCR, TPMT mutation kit.