Taq1 Polymorphism (rs731236) of Vitamin D Receptor Gene in Children with Acute Lymphoblastic Leukemia

Background: Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Several studies have shown that ALL occurs as a result of genetic abnormalities. 1, 25-Dihydroxyvitamin D3 as a secosteroid hormone plays an important role in different metabolic pathways. The normal function of vitamin D occurs via binding to a ligand-activated transcription factor i.e. vitamin D receptor (VDR). Therefore genetic variation in VDR may lead to various disorders, including cancer. We aimed to investigate rs731236 polymorphism of VDR gene in children with ALL. Methods: Genomic DNA was extracted from 50 children under 15 years of age with ALL and 50 age-matched healthy children’s whole blood and genetic variation of each participant was detected using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) with taqI restriction enzyme. Statistical analysis was performed using SPSS v.22 following χ2 test. Results: The VDR gene polymorphisms were genotyped in a total of 50 individuals with ALL, comparing 50 normal children with a mean age of 5.2±3.4 years. No deviation was observed from Hardy-Weinberg equilibrium (HWE) in the genotypic distribution of the rs731236 (χ2=0.25, P>0.05). Genotype frequency of TT (Dominant Homozygote), Tt (Heterozygote),  and tt (Recessive Homozygote), was 25, 15 and 10 in the case group and 21, 27 and 2 in the control group, respectively which showed a significant difference between two groups (P=0.011). tt genotype showed a strong protective effect against ALL over Tt (OR=9, CI 95%: 1.74-46.59). Conclusion: We have determined the frequency of Taq1 (rs731236) polymorphism in the VDR gene in children with ALL in Zanjan population. We concluded that genotype variation in VDR gene may have an effect on incidence of ALL.