Relationship Study Between HHEX Gene And Type 2 Diabetes Mellitus, Diabetic Nephropathy In Nouthern Han Chinese Population

Objective:This study was undertaken to demonstrate the associations between HHEX gene(rs1111875 loci)and type 2 diabetes mellitus, diabetic nephropathy in northern Han Chinese population; to investigate whether HHEX gene and its m RNA can serve as biomarkers for type 2 diabetes mellitus, diabetic nephropathy in northern Han Chinese population.Methods: The study was divided into two parts: “case-control” genetic association study and gene expression analysis. In the “case-control” genetic asssciation study, a total of 229 T2 DM cases and 389 unrelated healthy control subjects from northern Han Chinese population were included. Genomic DNA was extracted from peripheral blood leukocytes. One single nucleotide polymerphism(rs1111875 loci) in HHEX was genotyped by Taq Man allelic discrimination assays. SPSS software was used to identify age and gender differences between cases and controls. The goodness-of-fit χ2 test was applied to validate whether the genotypic distribution of rs1111875 loci was in Hardy-Weinberg equilibrium in the two groups. The distribution differences of allele frequencies and genotypic frequencies between cases and controls can be detected by the χ2 test. And then, demonstrating the association between HHEX gene and type 2 diabetes mellitus.In the gene expression analysis, a total of 61 subjects, including 19 type 2 diabetes mellitus cases( without complications), 22 diabetic nephropathy cases and 20 unrelated healthy controls from northern Han Chinese population, were included. Total RNA, timely isolated and extracted from peripheral blood leukocytes, was ultimately reverse transcribed into c DNA. The RT-QPCR method was taken to examine HHEX gene m RNA expression from peripheral blood leukocytes. The quantitative method of 2-? ?Ct was adopted to calculate HHEX gene m RNA expression. SPSS software was used to identify age and gender differences among the three groups; to distinguish whether the m RNA expression level in HHEX gene existed significant differences among type 2 diabetes mellitus cases(without complications), diabetic nephropathy cases and unrelated healthy controls. And then, demonstrating the associations between HHEX gene m RNA expression and type 2 diabetes mellitus, diabetic nephropathy.Results : In the "case-control" genetic association study, there were no significant differences in age and gender between the cases and controls(P>0.05). The goodness-of-fit χ2 test showed that the genotypic distribution of rs1111875 was in Hardy-Weinberg equilibrium in cases and controls. Pearson χ2 test revealed a significant difference in allelic frequencies between the patients and controls(χ2=3.905, OR=1.285, 95%CI(1.002-1.648); P=0.048), although there was no difference in genotypic frequencies between cases and controls( χ2=4.431, P=0.109).In the gene expression analysis, no significant difference was found in gender among the three groups(P>0.05). Significant difference was found in age by statistical analysis among the three groups(F=19.504, P=0.0000003). MannWhitney U test showed that the age in diabetic nephropathy group was significantly higher than that in type 2 diabetes group( P=0.00002) and the control(P=0.00001), although there was no difference between type 2 diabetes group and controls(P=0.232). Significant difference was found in HHEX m RNA expression level by statistical analysis among the the three groups(F=23.810, P=0.00000003; χ2=26.048, P=0.000002). Further analysis showed that HHEX m RNA expression level in diabetic nephropathy group was significantly higher than that in type 2 diabetes group(P=0.000001) and the control(P=0.00000004), however, there was no significant difference between type 2 diabetes group and controls(P=0.468). No significant difference was found in HHEX m RNA expression level between male and female. Pearson and Spearman ’s correlation analysis found no correlation between age and HHEX m RNA expression level in peripheral blood leukocytes(P > 0. 05).Conclusions:(1)Significant association was confirmed between HHEX gene(rs1111875 loci)and type 2 diabetes mellitus in northern Han Chinese Population. HHEX gene may be a susceptibility gene of type 2 diabetes mellitus in northern Han Chinese population.(2)There may be no correlations between HHEX m RNA expression level in peripheral blood leukocytes and gender, age.(3)HHEX m RNA expression level in diabetic nephropathy group was significantly higher than that in type 2 diabetes group and the control, however, there was no significant difference between type 2 diabetes group and controls.(4) HHEX gene m RNA may be served as a biomarker for diabetic nephropathy in northern Han Chinese population.