Screening of polymorphisms in the folate pathway in Turkish pediatric Acute Lymphoblastic Leukemia patients

Abstract

Background and aim: Folate metabolic pathway plays a significant role in leukemogenesis because of its necessity for nucleotide synthesis and DNA methylation. Folate deficiency causes DNA damage. Thus polymorphisms of folate-related genes may affect the susceptibility to childhood Acute Lymphoblastic Leukemia (ALL). MTHFR (Methylenetetrahydrofolate Reductase), DHFR (Dihydrofolate reductase), CBS (Cystathionine b-synthase) and TYMS (Thymidylate Synthase) have an important role in folate pathway because their activated variants modulate synthesis of DNA and levels of folate. In this study, we aimed to investigate whether polymorphisms in genes related to folate metabolic pathway influence the risk to childhood ALL.
Subject and methods: The patient groups who were diagnosed with childhood ALL at Losante Pediatric Hematology-Oncology Hospital and healthy control groups were included in the study. MTHFR 677 CT, MTHFR 1298 A-C, CBS 844ins68, DHFR 19-bp and TYMS 1494del6 polymorphisms were screened. Genotyping of these polymorphisms was performed by Restriction Fragment Length Polymorphism (RFLP) analysis and Real Time Polymerase chain Reaction (Real Time-PCR).
Results: In total, we have screened 5 polymorphisms in the studied genes. The results were compared between childhood ALL patients and healthy groups. Genotype frequencies of MTHFR 677 C-T, MTHFR 1298 A-C, CBS 844ins68 and DHFR 19-bp del were similar for childhood ALL patients and healthy groups. However, statistical results showed that TYMS 1494del6 may be associated with ALL pathogenesis (p < 0.001).
Conclusion: We showed that TYMS polymorphism (rs2853542) may be associated with ALL pathogenesis. In addition, our results demonstrated that MTHFR, DHFR and CBS do not affect development of leukemia. Our study displays also importance as it is the first screening results to identify association with the studied polymorphisms in Turkish patients with childhood ALL and determination of the frequency in Turkish population.