Association Between Common Genetic Polymorphism in MTNR1B and Susceptibility to Type 2 Diabetes Mellitus

Introduction: Type 2 diabetes Mellitus (T2DM) is a multifactorial, polygenic disease caused by impaired insulin secretion, insulin resistance and beta-cell dysfunction. Any imbalance in melatonin levels can be related to various metabolic disorders. Melatonin and the genetic variants of Melatonin Receptor 1B (MTNR1B) are reported to be associated with T2DM susceptibility. We investigated the association between rs4753426 single nucleotide polymorphisms (SNP) in the MTNR1B gene and the risk of developing T2D in group of Iranian people.Materials & Methods: : In this case-control study 208 individuals were recruited (108 T2DM cases and 100 normal controls). Genomic DNA was isolated from whole blood and genotyping was performed by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR- RFLP).Results:The frequencies of TT , CT and CC genotypes for the T2DM group were 91.67% , 0% and 8.33 % and 56% , 3% and 41% in the control group , respectively . Frequency of C allele among cases was significantly lower than controls (8.33% vs 42.5% respectively, p<0.001). The odds ratio for C allele was 0.12 (p<0.001)Conclusion: We found that patients with type 2 diabetes mellitus had significantly lower frequency of the genotypes of rs4753426 polymorphism of MTNR1B gene compared to normal population. In addition, the allelic investigation showed that carriers of C allele had 88% lower risk of developing diabetes mellitus compared to T allele carriers. Therefore, this allele can be a protective factor against diabetes mellitus. In conclusion, our study showed that rs4753426 polymorphism of MTNR1B gene can be associated with diabetes mellitus.