Association of GCK Gene Promoter Polymorphism and their Role in its mRNA Expression among Type 2 Diabetes Mellitus Patients

Abstract

Introduction: Glucokinase (GCK) gene alteration or inactivation leads to Maturity-Onset Diabetes of the Young (MODY) and Neonatal Diabetes. Alterations in GCK gene has been shown to be associated with increased risk of type 2 diabetes, hyperglycaemia and impaired beta cell function. Aim: To evaluate the GCK (-30G/A, rs1799884) alterations in Type 2 Diabetes Mellitus (T2DM) patients. Materials and Methods: After patients’ selection, blood samples were taken and all biochemical parameters were analysed by auto-analyser using serum. Whole blood samples were used to extract DNA and RNA for genotyping of -30G/A polymorphism using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) as well as GCKmRNA expression using quantitative real time PCR. Results: Several parameters such as fasting sugar, serum uric acid, Low Density Lipoprotein (LDL), High Density Lipoprotein (HDL), Triglyceride (TG), Cholesterol, high-sensitivity C-Reactive Protein (hs-CRP) were analysed among T2DM cases and healthy controls and differences among them were found to be significantly associated (p<0.0001). It was observed that patients who were smoking among T2DM cases, were found to be associated with increased fasting sugar (p=0.001), postprandial sugar (p<0.0001), HbA1c (p=0.003), blood urea (p=0.01), cholesterol (p=0.02) compared to those who were not smokers. T2DM patients who were alcoholic, showed increased LDL (p=0.006) and cholesterol (p=0.01) compared to non-alcoholic T2DM patients. T2DM cases which were reported hypertensive, showed increased hs-CRP (p=0.02) and cholesterol (p=0.02), compared to non-hypertensive T2DM cases and differences among them were found to be significantly associated. Significant differences were observed in distribution of GCK -30G/A genotypes among T2DM cases and healthy controls (p<0.0001). Odds ratio was calculated and it was observed that the heterozygous GA genotype had 4.66 odds ratio while odds ratio for mutant AA genotype was 35.98 in reference to wild type. Patients with homozygous GG showed 0.25 mean fold decreased GCK mRNA expression while heterozygous GA and mutant AA genotype showed more than 0.17 and 0.16 fold decreased. GCK mRNA was observed and differences among them was found to be significant (p<0.0001). Conclusion: Study revealed that GCK heterozygous GA and mutant AA genotypes were associated with T2DM risk and decreased expression may be responsible for disease progression and worsening of the disease.