Association Of MiRNAs And MTHFR Gene Polymorphisms With Ischemic Stroke In The Chinese Han Population

Background and objective:Ischemic stroke is considered to be a complex disease, which consists of a group of heterogeneous disorders with multiple genetic and environmental risk factors. MicroRNAs and methylenetetrahydrofolate reductase (MTHFR) participated in various physiopathological processes. Single nucleotide polymorphisms (SNPs) in miRNAs and MTHFR have been shown to be associated with susceptibility to many human diseases. Recently,4 well-known miRNAs polymorphisms in pre-miRNAs sequences (miR-146a C>G rs2910164, miR-149 T>C rs2292832, miR-196a2 T>C rs11614913 and miR-499 A>G rs3746444)have been studied to be associated with susceptibility to many diseases. However, the studies were few about these genetic polymorphisms associated with ischemic stroke, especially in the subtypes, and the results were different.The SNPs located in the 3’-untranslated region (3’-UTR) of MTHFR was associated with susceptibility to diseases through affecting miRNAs binding. At present, the study has not been reported about rs4846049 gene polymorphism of MTHFR associated with ischemic stroke and the interactions of MTHFR and miRNAs.The aim of this study was to investigate the association of miRNAs and MTHFR gene polymorphisms with ischemic stroke in the Chinese Han population.Methods:In our study, a case-control study was conducted. The subjects were randomly selected including 396 patients with ischemic stroke and 378 healthy people as control group, who met the study criteria. According to TOAST classification standards, the selected patients were divided into two subgroups:the large artery atherosclerosis (LAA) group and the small artery occlusion (SAO) group. The methods of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing were used to detect five SNPs genotypes, which were miR-146a C?G (rs2910164)、miR-196a2 T>C (rs11614913)、miR-499 A>G (rs3746444)、miR-149 T>C (rs2292832) and MTHFR G>T (rs4846049).The χ2 goodness of fit test was adopted to test the deviation of genotypes distribution in the study population from Hardy-Weinberg equilibrium. Logistic regression model was used to analyze the association of SNPs with ischemic stroke and the interactions among SNPs and environmental factors impact on ischemic stroke.The method of multifactor dimensionality reduction (MDR) was used to analyze the gene-gene interactions on ischemic stroke. We used the generalized linear model to analyze the associations among the SNPs and blood fat associated with ischemic stroke.Results:1. Each SNP genotype distribution in all subjects was accorded with Hardy-Weinberg equilibrium (P>0.05), which showed the selected population representative to be suitable for genetic analysis.2. The GG genotype of rs2910164 within miR-146a was significantly associated with an increased risk of ischemic stroke (OR=1.86,95%CI:1.19-2.88, P=0.006). In different genetic models were significantly associated with an increased risk of ischemic stroke (dominant model: OR=1.39,95%CI:1.04-1.86, P=0.027; recessive model:OR=1.62,95%CI:1.08-2.42, P=0.020; additive model:OR= 1.34,95%CI:1.09-1.65, P=0.006; allele model:OR=1.33,95%CI:1.09-1.64, P= 0.006). In subgroup analyses, LAA was significantly associated with the miR-146a C>G polymorphism (P<0.05). After adjustment for traditional risk factors only, GG genotype can increase the risk of SAO type (P<0.05).3. The CC genotype of rs2292832 within miR-149 was significantly associated with an increased risk of ischemic stroke (OR=2.00,95%CI:1.22-3.28, P=0.006). In different genetic models were significantly associated with an increased risk of ischemic stroke (dominant model: OR=1.42,95%CI:1.07-1.88, P=0.017; recessive model:OR=1.75,95%CI:1.09-2.82, P=0.020; additive model:OR=1.37,95%CI:1.11-1.7, P=0.004; allele model:OR=1.37,95%CI:1.11-1.7, P=0.004). In subgroup analyses, LAA was significantly associated with the miR-149 T>C polymorphism (P<0.05), however, it can’t significantly increase the risk of SAO type (P> 0.05).4. The TT genotype of rs4846049 within MTHFR was significantly associated with an increased risk of ischemic stroke (OR=2.87,95%CI:1.43-5.76, P=0.003). In different genetic models were significantly associated with an increased risk of ischemic stroke (dominant model: OR=1.71,95%CI:1.28-2.28, P<0.001; recessive model:OR=2.41,95%CI:1.21-4.8, P=0.012; additive model:OR=1.63,95%CI:1.28-2.08, P<0.001; allele model:OR=1.62,95%CI:1.28-2.06, P< 0.001). In subgroup analyses, LAA was significantly associated with the MTHFR G>T polymorphism (P<0.05). It can also increase the risk of SAO type (P<0.05), but after correcting for the traditional risk factors, it can’t reach significantly statistical difference (P> 0.05).5. However, we failed to find any association among the alleles/genotypes of miR-196a2 T>C (rsl 1614913) and miR-499 A>G (rs3746444) with ischemic stroke, respectively (P>0.05) In subgroup analyses, we also not found any association in LAA and SAO types (P> 0.05).6. We failed to find the significant interactions amomg miR-146a C>G (rs2910164), miR-149 T>C (rs2292832) and MTHFR G>T (rs4846049) with smoking, drinking, hypertension and diabetes (P> 0.05).7. We found the significant gene-gene interactions among miR-196a2 T>C (rs11614913), miR-499 A>G (rs3746444) and MTHFR G>T (rs4846049) (P< 0.05).8. The total cholesterol levels were significantly correlated with miR-149 T>C (rs2292832) and MTHFR G>T (rs4846049) in the case group (P<0.05); however, we did not find the significant correlations among miR-146a C>G (rs2910164) and the blood lipid levels (P> 0.05).Conclusions:1.This study indicates that miR-146a C>G (rs2910164) and miR-149 T>C (rs2292832) might be associated with a significantly increased risk of ischemic stroke in the Chinese Han population, which might be mainly associated with an increased risk of LAA stroke.2. We found for the first time that MTHFR G>T (rs4846049) might be associated with a significantly increased risk of ischemic stroke, which might be mainly associated with an increased risk of LAA stroke in the Chinese Han population.3. miR-196a2 T>C (rs11614913) and miR-499A>G(vs3746444) might not be associated with ischemic stroke in the Chinese Han population.4. The susceptibility to ischemic stroke might not be caused by the interactions among miR-146a C>G, miR-149 T>C, MTHFR G>T with smoking, drinking, hypertension and diabetes in the Chinese Han population.5. The interactions of miR-196a2 T>C (rsl 1614913), miR-499 A>G (rs3746444) and MTHFR G>T (rs4846049) might influence the risk of ischemic stroke in the Chinese Han population.6. The SNPs of miR-149 T>C (rs2292832) and MTHFR G>T (rs4846049) might increase the risk of ischemic stroke by influencing the lipid metabolism.Background and objective:The association between the methylene-tetrahydrofolate reductase (MTHFR) gene C677T polymorphism and ischemic stroke (IS) has been extensively studied; however, the results from genetic association studies have been inconsistent even in the Chinese population. Therefore, the aim of our meta-analysis was to further evaluate the association in the Chinese population.Methods:We collected all of the relevant studies from Pubmed, OVID, Embase, Chinese Wan Fang database, CNKI, Chongqing VIP database and CBM up to August 2014. The available data was analyzed by Stata (version 12.0). We used odds ratios (ORs) and corresponding 95% confidence intervals (CIs) to present the strength of the association. Heterogeneity was evaluated by the Q-test and I2statistic. Different genetic models, subgroup analysis, publication bias and sensitivity analysis were used to improve the comprehensive understanding.Results:The results showed a significant association between the MTHFR gene C677T polymorphism and ischemic stroke in six genetic models (additive model:OR=1.34,95%CI: 1.17-1.54, P< 0.001; dominant model:OR=1.44,95%CI:1.26-1.64, P<0.001; recessive model: OR=1.45,95%CI:1.15-1.83, P=0.001; heterozygote model:OR=1.35,95%CI:1.18-1.55, P 0.001; homozygote model:OR=1.80,95%CI:1.34-2.41, P< 0.001; and allelic model:OR=1.34, 95%CI:1.17-1.53, P<0.001) based on the overall population, as well as subgroup analysis. In addition, the similar results were obtained in the sensitivity analysis based on studies with the high quality.Conclusions:This meta-analysis presented a significant association between the MTHFR gene C677T polymorphism and ischemic stroke, the T allele might be a risk factor for ischemic stroke in the Chinese population.