Association of acute ischemic stroke with the MTHFR C677T polymorphism but not with NOS3 gene polymorphisms in a Singapore population

Associations of MTHFR gene polymorphism with lipid metabolism and risk of cerebral infarction in the Northwest Han Chinese population

Objective

Genetic variation in the methylenetetrahydrofolate reductase (MTHFR) gene may contribute to the development of cerebral infarction (CI); however, results have been inconsistent across studies with different populations, including studies of the Chinese population. The aim of this study was to analyze the effect of MTHFR gene polymorphism on serum lipid and homocysteine levels among patients with CI in the Northwest Chinese Han population.

Patients and methods

A total of 521 CI patients and 524 non-CI controls were enrolled in the study. Polymerase chain reaction and hybridization were utilized to identify MTHFR gene polymorphisms. Multivariate logistic regression analysis was used to assess the associations of MTHFR gene polymorphism with risk of CI.

Results

Frequencies of the TT genotype and the T allele were markedly higher among CI patients than among controls. After stratifying our data by sex and age, we determined that these differences in frequency of the TT genotype and the T allele were statistically significant among participants of two different age brackets and among men, but not among women (i.e., there were no statistically significant differences between female patients and female controls). CI patients and control participants with the CT or TT genotype had significantly higher homocysteine (Hcy) levels than those with the CC genotype. Among CI patients, CT/TT carriers showed significantly lower high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (ApoA-I) levels as compared with CC carriers, but there was no significant difference for control participants. Multivariable logistic regression analysis showed that drinking; smoking; diabetes mellitus; levels of Hcy, direct bilirubin (DB), indirect bilirubin (IB), ApoA-I, and total protein (TP); and TT genotype were significant independent risk factors for CI.

Conclusions

The results suggested that the TT genotype of the MTHFR C677T gene polymorphism, which is associated with hyperhomocysteinemia (HHcy), might be of great clinical significance in the identification of new biomarkers for CI and in the development of individualized preventive and therapeutic strategies.

Association of methylenetetrahydrofolate reductase (MTHFR) rs1801133 (677C>T) gene polymorphism with ischemic stroke risk in different populations: An updated meta-analysis

Background: Recently, increasing evidence has implicated methylenetetrahydrofolate reductase (MTHFR) gene mutation as a risk factor for ischemic stroke (IS) in the general population. However, studies have been inconclusive and lack evidence on specific populations. We aim to determine whether the rs1801133 (NC_000001.11 (MTHFR):g. 677C>T (p.Ala222Val) variant, we termed as MTHFR rs1801133 (677 C>T), is linked to an increased risk of IS in different age groups and ancestry groups. Methods: The literature relevant to our study was found by searching the PubMed, Cochrane Library, Web of Science, EMBASE, and CNKI databases. A random effect model analysis was used to calculate the pooled odds ratio (OR) and 95% confidence interval (CI) to evaluate any possible association. We conducted a subgroup analysis based on the age and ancestry groups of the included populations. Results: As of March 2022, 1,925 citations had been identified in electronic databases, of which 96 studies involving 34,814 subjects met our eligibility criteria. A strong link was found between IS and the MTHFR gene rs1801133 (677C>T) polymorphism in all genetic models [dominant genetic model (OR = 1.47; 95%CI = 1.33-1.61; p < 0.001), recessive genetic model (OR = 1.52; 95%CI = 1.36-1.71; p < 0.001), heterozygous model (OR = 1.36; 95%CI = 1.24-1.48; p < 0.001), homozygous model (OR = 1.82; 95%CI = 1.58-2.11; p < 0.001), and T allelic genetic model (OR = 1.37; 95%CI = 1.27-1.48; p < 0.001)]. Further subgroup analyses indicated that the MTHFR rs1801133 (677C>T) variant may increase the risk of IS in Asian, Hispanic, or Latin population, middle-aged, and elderly populations (p < 0.001). Conclusion: Our results implied that mutation of the T allele of MTHFR rs1801133 (677C>T) could be a risk factor for IS. A significant association was found among Asian, Hispanic, or Latin population, middle-aged, and elderly people.

Large-Scale Targeted Sequencing Study of Ischemic Stroke in the Han Chinese Population

Background Ischemic stroke is likely caused by interactions of multiple genes and environmental determinants. However, large-scale sequencing studies to discern functional genetic variants and their interactions with clinical and lifestyle risk factors on ischemic stroke are limited. Methods and Results We sequenced functional regions of 740 previously identified genes associated with atherosclerotic disease among 999 ischemic stroke cases and 1001 controls of Chinese ancestry. Multiple logistic regression models were used to examine the associations between variants and ischemic stroke and test interactions between variants and clinical and lifestyle risk factors. Functional variants achieving suggestive significance were replicated in an independent sample of 4724 ischemic stroke cases and 5029 controls. Driven by variant main effects, each minor allele of the correlated rs174535, rs174545, and rs3834458 variants at MYRF-FADS1-FADS2 conferred an average 0.83-fold (95% CI, 0.78-0.88) decreased odds of stroke. Significant main effects of MTHFR rs1801133 missense variant were also observed, with each copy of the A allele associated with a 1.20-fold (95% CI, 1.13-1.27) higher odds of ischemic stroke. The functional ALDH2 rs671 variant was identified in interaction analyses with alcohol drinking (Meta-P=3.39×10-17). Each minor allele conferred a 0.54-fold (95% CI, 0.45-0.64) decreased odds of stroke among drinkers and a 0.89-fold (95% CI, 0.83-0.97) decreased odds among nondrinkers. Conclusions Significant associations at MYRF-FADS1-FADS2 indicate that genetically elevated polyunsaturated fatty acids may decrease ischemic stroke risk in East Asians. Significant associations at MTHFR and ALDH2 robustly confirm deleterious effects of genetically elevated homocysteine and alcohol intake, respectively, on ischemic stroke.

Relationship of Methylenetetrahydrofolate Reductase (MTHFR) C677T Variation With Susceptibility of Patients With Ischemic Stroke: A Meta-Analysis

Discovery and validation of genetic factors for multifactorial and polygenic disorders like stroke are needed to make progress in precision medicine. Although some traditional risk factors for stroke have been identified, they do not fully explain the pathophysiological mechanism of ischemic stroke. The research of genetic risk factors is becoming increasingly relevant in the understanding of stroke mechanisms and the finding of population-specific therapeutic targets. The methylenetetrahydrofolate reductase (MTHFR) gene is involved in homocysteine metabolism, and a high homocysteine level is a risk factor for stroke. Using a meta-analysis technique, we investigated the link between the MTHFR C677T gene polymorphism and the risk of ischemic stroke.

We used the electronic databases PubMed, Medline, Embase, and Google Scholar to find articles in the Journal of Stroke. If heterogeneity was more than 50%, pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random-effects model; otherwise, a fixed-effects model was used.

A total of 67 case-control studies with 17,704 cases and 21,981 controls met our inclusion criteria. The Asian population was represented by 41 studies, whereas the Caucasian population was represented by 26. Under the recessive model, a gene polymorphism at the 677 location of the MTHFR gene is related to an elevated risk of ischemic stroke (OR: 1.29, 95% CI: 1.22-1.37, P < 0.001).

People who have the MTHFR C677T gene polymorphism have a greater risk of stroke than people who do not.

Hyperhomocysteinemia and Ischemic Stroke: A Potential Dose-Response Association-A Systematic Review and Meta-analysis

Background and Purpose  Previous studies suggest an association between increased homocysteine (Hcy) and risk of ischemic stroke. Yet, it remains unknown whether a dose-response association exists between Hcy levels and risk of ischemic stroke. Methods  Systematic literature searches were performed in PubMed, Embase, Scopus, and Web of Science. Inclusion criteria were studies investigating ischemic stroke risk in an adult population with measured Hcy levels. We computed odds ratios (ORs) for a 5 µmol/L increase in Hcy levels using a random effects meta-analysis. Results  In total, 108 studies met the inclusion criteria of which 22 were rated as high-quality studies, and 20 studies included a dose-response analysis. Hcy levels were analyzed either as a continuous or categorical variable. The majority of the studies found an increased risk of ischemic stroke when comparing the highest-to-lowest Hcy strata. A graded association was observed over the Hcy strata, indicating a dose-response association, with the most apparent effect when Hcy levels exceeded approximately 15 µmol/L. No studies explored a potential nonlinear association between Hcy levels and ischemic stroke. Six studies were included in a meta-analysis, showing an OR of 1.43 (95% confidence interval [CI]: 1.28-1.61) per 5 µmol/L increase in Hcy levels. Conclusion  This review and meta-analysis indicate a dose-response association between Hcy levels and ischemic stroke. An evident increase in effect measures was observed when Hcy levels exceeded 15 µmol/L, indicating a nonlinear association between ischemic stroke and Hcy levels. This nonlinear association warrants further study. This study is registered with clinical trial ( https://www.crd.york.ac.uk/prospero/ ; unique identifier: CRD42019130371).

Gene polymorphisms in calcium-calmodulin pathway: Focus on cardiovascular disease

Cardiovascular disease is the leading cause of death in industrialized countries and affects an increasing number of people. Several risk factors play an important role in the etiology of this disease, such as an unhealthy lifestyle. It is increasingly clear that genetic factors influencing the molecular basis of excitation-contraction mechanisms in the heart could contribute to modify the individual's risk. Thanks to the progress that has been made in understanding calcium signaling in the heart, it is assumed that calmodulin can play a crucial role in the excitation-contraction coupling. In fact, calmodulin (CaM) binds calcium and consequently regulates calcium channels. Several works show how some polymorphic variants can be considered predisposing factors to complex pathologies. Therefore, we hypothesize that the identification of polymorphic variants of proteins involved in the CaM pathway could be important for understanding how genetic traits can influence predisposition to myocardial infarction. This review considers each pathway of the three different isoforms of calmodulin (CaM1; CaM2; CaM3) and focuses on some common proteins involved in the three pathways, with the aim of analyzing the polymorphisms studied in the literature and understanding if they are associated with cardiovascular disease.

A prospective cohort study of MTHFR C677T gene polymorphism and its influence on the therapeutic effect of homocysteine in stroke patients with hyperhomocysteinemia

BACKGROUND

Hyperhomocysteinemia (HHCY) is a risk factor for cardiovascular and cerebrovascular diseases. The C677T 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism increases homocysteine (HCY) levels. This study analyzed the relationship between C677T MTHFR polymorphism and the therapeutic effect of lowering HCY in stroke patients with HHCY.

METHODS

Baseline data were collected from stroke patients with HHCY for this prospective cohort study. The C677T MTHFR genotype was detected by polymerase chain reaction-restriction fragment length polymorphism and the therapeutic effect to reduce HCY was compared.

RESULTS

Of 200 stroke patients 162 (81.0%) completed follow-up and were evaluated. Most of them responded well to treatment (103 cases, 63.5%), but 59 (36.4%) patients were in the poor efficacy group. There was a significant difference in terms of age (P < 0.001), hypertension (P = 0.041), hyperuricemia (P = 0.042), HCY after treatment (P < 0.001), and MTHFR genotype (P < 0.001) between the poor efficacy and effective groups, with increased frequency of the TT genotype in the poor efficacy group. Logistic regression showed that the T allele was associated with poor efficacy (OR = 0.733, 95%CI: 0.693, 0.862, P < 0.001). In the codominant model the TT genotype was associated with poor outcome (OR = 0.862, 95%CI: 0.767, 0.970, P = 0.017) and this was also the case in the recessive model (OR = 0.585, 95%CI: 0.462, 0.741, P < 0.001) but there was no association between CT and TT in the dominant model.

CONCLUSIONS

The T allele and TT genotype of the MTHFR C677T polymorphism was associated with poor HCY reduction treatment efficacy in stroke patients with HHCY.

TRIAL REGISTRATION

The registration number of the clinical trial is ChiCTR1800020048. Registration date: December 12, 2018.

Shared genetic risk factors for depression and stroke

BACKGROUND

The comorbidity of major depressive disorder (MDD) and stroke are common in clinic. There is a growing body of evidence suggesting a bi-directional relationship between stroke and depression. However, the mechanisms underlying the relationship between MDD and stroke are poorly investigated. Considering that both MDD and stroke can be heritable and are influenced by multiple risk genes, shared genetic risk factors between MDD and stroke may exist.

OBJECTIVE

The objective is to review the existing evidence for common genetic risk factors for both MDD and stroke and to outline the possible pathophysiological mechanisms mediating this association.

METHODS

A systematic review and meta-analysis was performed. Gene association studies regarding stroke and depression were searched in the database PubMed, CNKI, and Chinese Biomedical Literature Database before December 2018. Statistical analysis was performed using the software Revman 5.3.

RESULTS

Genetic polymorphisms of 4 genes, methylenetetrahydrofolate reductase (MTHFR) and apolipoprotein E (ApoE) have been demonstrated to associate with the increased risk for both MDD and stroke, while the association between identified polymorphisms in angiotensin converting enzyme (ACE) and serum paraoxonase (PON1) with depression is still under debate, for the existing studies are insufficient in sample size. These results suggest the possible pathophysiological mechanisms that are common to these two disorders, including immune-inflammatory imbalance, increased oxidative and nitrative stress, dysregulation of lipoprotein and lipid metabolism, and changes of cerebrovascular morphology and function. Other associated genes with few or conflicting results have also been included, and a few studies have investigated the effects of the described polymorphisms on MDD and stroke comorbidity, such as post stroke depression.

CONCLUSION

These findings suggest that shared genetic pathways may contribute to the comorbidity of MDD and stroke. Studies to evaluate the shared genetic variations between MDD and stroke may provide insights into the molecular mechanisms that trigger disease progression.

Genetic polymorphisms of methylenetetrahydrofolate reductase C677T and risk of ischemic stroke in a southern Chinese Hakka population

Previous studies have shown that methylenetetrahydrofolate reductase (MTHFR) gene to be a genetic risk factor for the susceptibility to ischemic stroke. The aim of this case-control study was to investigate whether the polymorphisms of MTHFR C677T were associated with the susceptibility to ischemic stroke in a southern Chinese Hakka population. In this study, a total of 1967 ischemic stroke patients and 2565 controls of Chinese Hakka ethnicity were recruited. The MTHFR C677T polymorphisms were genotyped by polymerase chain reaction (PCR) amplification and microarray method. The risk of ischemic stroke was estimated by logistic regression analysis. The frequencies of CC, CT, and TT genotypes were 52.67% versus 55.63%, 40.31% versus 38.52%, and 7.02% versus 5.85% in patients with ischemic stroke versus controls, respectively. The frequency of T allele was significantly higher in ischemic stroke patients (27.17%) than in controls (25.11%) (P = .026, odds ratio [OR] 1.113, 95% confidence interval [CI] 1.013-1.223). The homozygous TT genotype in the ischemic stroke patients was associated with increased risk (P = .049, OR 1.132, 95% CI 1.001-1.281) when compared with the controls after adjustment for age and sex. The positive association was only found in dominant model without adjustment for age and sex (P = .047, OR 1.127, 95% CI 1.002-1.268). Also, the carrier status of the MTHFR T allele was identified as an independent risk factor for the development ischemic stroke even after the adjustment for conventional risk factors (P = 0.047, OR 1.109, 95% CI 0.964-1.225). Our results provide evidence that variants of MTHFR C677T gene may influence the risk of developing ischemic stroke in a southern Chinese Hakka population. Further studies are needed to confirm this association, which will promote the development of strategies for prevention and treatment of ischemic stroke in our study population.

Methylenetetrahydrofolate reductase C677T variant and hyperhomocysteinemia in subarachnoid hemorrhage patients from India

Methylenetetrahydrofolate reductase (MTHFR) polymorphism (C677T, A1298C) has been implicated in increased plasma homocysteine (Hcy) levels. The present study was designed to investigate the association between MTHFR polymorphism and increased Hcy levels in subarachnoid haemorrhage (SAH) patients. A total of 150 subjects from North India were included in the study, comprising of 100 SAH patients and 50 healthy controls. Plasma Hcy levels was determined and MTHFR polymorphism (C677T, A1298C) was screened by High resolution melting (HRM) analysis. Plasma Hcy levels were found to be significantly higher (p < 0.001) in SAH patients than in healthy controls. No significant difference in the genotype and allele frequency of MTHFR A1298C was observed. However, frequency of MTHFR C677T genotype, CT (53% vs. 20%; p < 0.001) and TT (15% vs. 2%; p < 0.05) was significantly higher in SAH group as compared to healthy controls. The frequency of T allele (41.5% vs. 12%; p < 0.001) was also found to be higher in SAH patients in comparison to healthy controls. Furthermore, Hcy levels were higher in SAH patients with TT genotype than in patients having CT genotype, whereas CC genotype had lower Hcy levels. The study suggests that higher frequency of MTHFR C677T allele may contribute to etiopathology of SAH through increase in Hcy levels.

The MTHFR C677T Polymorphism and Risk of Intracerebral Hemorrhage in a Chinese Han Population

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism has been speculated to be and extensively investigated as a risk factor for various vascular diseases, including intracerebral hemorrhage (ICH). However, results from published studies regarding the role of C677T polymorphism in ICH risk in Chinese populations were contradictory rather than conclusive.

MATERIAL/METHODS

In this study, a total of 180 ICH patients and 180 matched controls of Chinese Han ethnicity were enrolled. The MTHFR C677T polymorphism was genotyped by polymerase chain reaction-ligation detection reaction (PCR-LDR). A meta-analysis was conducted by combining our data with previous relevant studies in Chinese populations.

RESULTS

In our case-control study, similar allele frequency (p=0.492) and genotype distribution (p=0.748) of MTHFR C677T polymorphism were detected between ICH patients and controls. Further analysis based on hematoma location did not show a significant association. When combined with previous studies, however, C677T polymorphism was found to be significantly associated with an increased risk for ICH in Chinese populations (recessive model: OR=1.57, 95%CI=1.29-1.91). When focusing on the Han ethnicity, carriers of the TT genotype had an increased risk of ICH (recessive model: OR=1.36, 95%CI=1.05-1.75).

CONCLUSIONS

In this case-control study we did not observe that the MTHFR C677T polymorphism was associated with ICH risk in people of Chinese Han ethnicity. However, when combined with previous published studies, a significant association of C677T polymorphism with an increased risk of ICH was detected in Chinese populations, and also in the subgroup analysis focusing on Han ethnicity.

Association between 5,10-Methylenetetrahydrofolate Reductase C677T Gene Polymorphism and Risk of Ischemic Stroke: A Meta-analysis

BACKGROUND

Hyperhomocysteinemia, a condition that is strongly determined by dietary intake of B vitamins, has been suggested to be an independent risk factor for ischemic stroke (IS). To test this hypothesis, we performed a meta-analysis to investigate the associations between 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism, which plays a critical role in modulating plasma homocysteine concentrations, and IS risk.

MATERIALS AND METHODS

We searched case-control studies on the association between MTHFR C677T genetic polymorphism and susceptibility to IS through PubMed, Embase, and Medline databases from January 2000 up to October 2014. The random-effects model was employed because moderate heterogeneity across studies was observed, as assessed by I(2) statistic. Publication bias was estimated using funnel plot and Egger's regression test.

RESULTS

A total of 22 case-control studies were included in the current meta-analysis. Significant associations between MTHFR C677T genetic polymorphism and IS were found under the dominant model (pooled odds ratio [OR] = 1.40, 95% confidence interval [CI]: 1.24-1.57), the recessive model (pooled OR = 1.37, 95% CI: 1.16-1.61), and the allele model (pooled OR = 1.29, 95% CI: 1.18-1.42).

CONCLUSIONS

The meta-analysis suggests that MTHFR C677T genetic polymorphism is significantly associated with susceptibility to IS, which provides evidence supporting hyperhomocysteinemia as a risk factor for stroke.

Quantitative assessment of association between rs1801133 polymorphism and susceptibility to stroke

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism, which is essential for DNA synthesis and methylation. Genetic variations in the MTHFR gene seem to contribute to a decreased activity of MTHFR, ultimately confer increased susceptibility to stroke. To assess the association between this polymorphism and stroke risk, we conducted a comprehensive meta-analysis based on 73 eligible studies. A total of 73 studies, including 10,225 cases and 13,800 controls identified between 1999 and 2012, were selected through researching the PubMed, MEDLINE, EMBASE, Cochrane Library, Web of Science, and Chinese Biomedical Chinese National Knowledge Infrastructure and Literature database databases. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to assess the association. Overall, a significant elevated risk of stroke risk was associated with the rs1801133 polymorphism in all genetic models (homozygote model: OR 1.296, 95% CI 1.109-1.514; dominant model: OR 1.179, 95% CI 1.058-1.315; recessive model: OR 1.209, 95% CI 1.063-1.375; allele comparison model: OR 1.154, 95% CI 1.061-1.256). In the stratified analyses, significantly increased stroke risks were indicated among Asians in all genetic models (homozygote model: OR 1.726, 95% CI 1.314-2.267; dominant model: OR 1.535, 95% CI 1.282-1.838; recessive model: OR 1.452, 95% CI 1.160-1.818; allele comparison model: OR 1.403, 95% CI 1.211-1.626).The present meta-analysis suggests that rs1801133 polymorphism contributes to the risk of stroke, of note, in Asian populations.

[Analysis of the effect of N5, N10-methylenetetrahydrofolate reductase gene C(677)-->T polymorphism on the ischemic stroke development in persons with various risk factors]

The results ofMTHFR gene C(677)-->T (rs1801133) polymorphism determined in 170 patients with ischemic atherothrombotic stroke (IATS) and 124 healthy subjects (control group) are presented in the paper. It has been shown that in patients with IATS, the frequencies of main homozygotes (CC), heterozygotes (CT) and minor homozygotes (TT) are 52.4, 35.9, 11.8% (in control--46.0, 48.4, 5.6%, P = 0.044 by chi2-test). TT homozygotes have a greater chance of developing IATS than carriers of main C-allele (CT + CC) (OR = 2.3, CI = 0.911-5.449, P = 0.049). In the representatives of the Ukrainian population there is a relationship between the frequency of MTHFR gene C(677)-->T polymorphism genotypes and the risk of IATS. This connection is manifested in male patients, in persons with normal blood pressure, and in people who do not have the habit of smoking. The sex of the patients, body mass index, blood pressure and smoking affect the level of the studied polymorphism association with stroke.

Relationship between endothelial nitric oxide synthase gene polymorphisms and ischemic stroke: a meta-analysis

OBJECTIVES

Previous studies examining whether polymorphisms (G894T, 4b/a, and T786C) in the endothelial nitric oxide synthase (eNOS) gene are associated with ischemic stroke have yielded conflicting results. We performed a meta-analysis to investigate the potential association between these three eNOS gene polymorphisms and ischemic stroke risk.

MATERIALS AND METHODS

We searched databases until April 30, 2012 and used fixed or random effects models to estimate the pooled odds ratios (ORs).

RESULTS

We analyzed 34 case-control data sets from 33 publications involving 5261/5823 cases/controls for G894T, 4295/4682 for 4b/a, and 2698/3254 for T786C polymorphisms. For Asian populations, all models showed significantly increased risk of ischemic stroke for the G894T (dominant model: OR = 1.58; 95% CI, 1.30-1.91; P = 0.000) and 4b/a polymorphisms (dominant model: OR = 1.46; 95% CI, 1.25-1.71; P = 0.000), even after Bonferroni correction (because 0.000 < 0.017). In white populations, the aa genotype seemed to be protective for ischemic stroke, as indicated by the recessive model (OR = 0.44; 95% CI, 0.22-0.87; P = 0.019). In Asian populations, the T786C polymorphism was significantly associated with ischemic stroke, as found using the dominant (OR = 1.17; 95% CI, 1.02-1.34; P = 0.025) and additive models (OR = 1.18; 95% CI, 1.05-1.33; P = 0.006).

CONCLUSIONS

Our comprehensive meta-analysis ascertains that the G894T, 4b/a, and T786C polymorphisms are associated with ischemic stroke risk in Asians. A possible contrasting role of the 4b/a polymorphism in ischemic stroke was indicated in white populations.

An updated meta-analysis of endothelial nitric oxide synthase gene: three well-characterized polymorphisms with ischemic stroke

Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene may influence the risk of ischemic stroke (IS), but the results are still debatable. A meta-analysis was performed to investigate the association between the eNOS gene polymorphisms in IS risk. Case-control studies on the association between the G894T, T-786C, and 4b/a polymorphisms and IS were searched up to July 2012, and the genotype frequencies in the control group were found to be consistent with the Hardy-Weinberg equilibrium (HWE). The effect summary odds ratio (OR) and 95% confidence intervals (CIs) were obtained. Meta-regression was used to explore the potential sources of heterogeneity. Funnel plots and Egger's test was used to estimate small study biases, and heterogeneity was assessed by chi-square-based Q-test and I(2) test. There were total 6537/6475 cases/controls for G894T, 3459/3951 cases/controls for 4b/a, and 2125/2673 cases/controls for T-786C polymorphism. For G894T and 4b/a, a significant association of 894T allele and 4a allele with increased risk of IS was found in Asians (TT+GT vs. GG: p<0.00001, OR=1.60, 95% CI=1.38-1.79, Pheterogeneity=0.11; aa+ba vs. bb: P<0.00001, OR=1.60, 95% CI=1.30-1.97, Pheterogeneity=0.02), but not in Caucasians (TT+GT vs. GG: P=0.60, OR=0.94, 95% CI=0.75-1.19, Pheterogeneity=0.002; aa+ba vs. bb: P=0.13, OR=0.81, 95% CI=0.62-1.06, Pheterogeneity=0.63). For T-786C polymorphism, there were no significant differences in genotype distribution between IS and control in Asians (CC+TC vs. TT: P=0.15, OR=1.14, 95% CI=0.95-1.37, Pheterogeneity=0.94) and in Caucasians (CC+TC vs. TT: P=0.72, OR=0.96, 95% CI=0.75-1.22, Pheterogeneity=0.53). This analysis provides strong evidence that the eNOS T-786C gene polymorphism is not associated with IS, the G894T and 4b/a polymorphisms might be associated with IS, at least in Asians.

Endothelial NO synthase gene polymorphisms and risk of ischemic stroke in Asian population: a meta-analysis

Background

The association between polymorphism 4b/a, T-786C and G894T in endothelial NO synthase gene (eNOS) and ischemic stroke (IS) remains controversial in Asian. A meta-analysis was performed to better clarify the association between eNOS gene and IS risk.

Methods

Based on the search of PubMed, Web of Science (ISI), CNKI (National Knowledge Infrastructure), Wan Fang Med Online and CBM (Chinese Biology Medical Literature Database) databases, all eligible case-control or cohort studies were identified. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) from fixed and random effect models were calculated. Heterogeneity among studies was evaluated using the I². Meta-regression was used to explore the potential sources of between-study heterogeneity. Begg's test was used to estimate publication bias.

Results

Our study included 27 articles, contained 28 independent case–control studies, involved a total of 3,742 cases and 3,691 controls about 4b/a, 1,800 cases and 1,751 controls about T-786C and 2,747 cases and 2,872 controls about G894T. A significant association of 4a allele with increased risk of IS was found in dominant (FEM: OR = 1.498, 95% CI = 1.329–1.689), recessive (FEM: OR = 2.132, 95% CI = 1.383–3.286) and codominant (REM: OR = 1.456, 95% CI = 1.235–1.716) models. For T-786C and G894T, there were significant associations with dominant and codominant genetic models, but not with recessive genetic model.

Conclusions

The meta-analysis indicated that eNOS gene 4b/a, T-786C, G894T polymorphism might be associated with IS.

A tailed primers protocol to identify the association of eNOS gene variable number of tandem repeats polymorphism with ischemic stroke in Chinese Han population by capillary electrophoresis

Endothelial nitric oxide synthase (eNOS) plays an important role in mediating endothelium-dependent vasodilatation and antithrombotic action and is thus involved in the development of ischemic stroke (IS). Controversial results regarding the association of eNOS gene variable number of tandem repeats (VNTR) polymorphism with IS have been reported by conventional PCR-polyacrylamide gel electrophoresis methods. We aimed to identify any common association of eNOS gene VNTR polymorphism with IS in Chinese Han population by capillary electrophoresis (CE). The VNTR polymorphism of 27 bp within the eNOS intron-4 was determined by CE with specially designed tailed primers in Chinese Han patients with IS (n=457) and matched elderly controls without IS (n=457). Significant differences in BMI, WHR, hypertension, diabetes, smoking, TG, HDL, LDL, LDL, and FBG were observed between cases and controls. The distributions of eNOS VNTR polymorphism were not significantly associated with IS after adjustment for cardiovascular risk factors (OR=1.18, 95% CI: 0.82-1.69). This finding was consistent with the further meta-analysis in Asians. The meta-analysis in Americans demonstrated that 4a/4b+4a/4a genotype was significantly associated with IS risk with an OR of 1.54 (95% CI, 1.09-2.17) compared with the 4b/4b genotype. Our data suggests that BMI, WHR, hypertension, diabetes, smoking, TG, LDL, and FBG may increase the risk of IS. However, eNOS VNTR polymorphism may be not an independent major contributor for IS in Chinese Han population. The VNTR polymorphism might be associated with IS in Americans based on meta-analysis.

Association of G894T polymorphism in endothelial nitric oxide synthase gene with the risk of ischemic stroke: A meta-analysis

Findings of a previous meta-analysis demonstrated no association between G894T polymorphism in endothelial nitric oxide synthase (eNOS) gene and ischemic stroke. Results of other studies have also been inconsistent. Updated meta-analysis was performed to assess the association between the eNOS gene G894T (rs1799983) polymorphism and the risk of ischemic stroke. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) from fixed and random effects models were calculated. Heterogeneity in the studies was evaluated using the I². Meta-regression and the 'leave-one-out' sensitive analysis were used to examine the potential sources of between-study heterogeneity. Publication bias was estimated using the Egger's test. Data were available for 6,607 cases and 6,947 controls from 22 studies. Studies deviating from the Hardy-Weinberg equilibrium (HWE) in the controls and the key contributors to between-study heterogeneity were excluded. Significant associations between eNOS gene G894T polymorphism and the risk of ischemic stroke were observed in the dominant (OR 1.249; 95% CI, 1.145-1.361), the recessive (OR 1.255; 95% CI, 1.082-1.456) and the codominant models (OR 1.195; 95% CI, 1.115-1.281). Moreover, in the subgroup analysis based on the region (Asia and Europe), significant associations were observed between the dominant and codominant genetic models but not in the recessive model. The results of our meta-analysis suggested that eNOS gene G894T polymorphism was associated with the increased risk of ischemic stroke, and that the T allele may be an important risk factor for ischemic stroke. However, further studies are required to confirm this result.

A novel multiplex PCR-RFLP method for simultaneous detection of the MTHFR 677 C > T, eNOS +894 G > T and - eNOS -786 T > C variants among Malaysian Malays

BACKGROUND

Hyperhomocysteinemia as a consequence of the MTHFR 677 C > T variant is associated with cardiovascular disease and stroke. Another factor that can potentially contribute to these disorders is a depleted nitric oxide level, which can be due to the presence of eNOS +894 G > T and eNOS -786 T > C variants that make an individual more susceptible to endothelial dysfunction. A number of genotyping methods have been developed to investigate these variants. However, simultaneous detection methods using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis are still lacking. In this study, a novel multiplex PCR-RFLP method for the simultaneous detection of MTHFR 677 C > T and eNOS +894 G > T and eNOS -786 T > C variants was developed. A total of 114 healthy Malay subjects were recruited. The MTHFR 677 C > T and eNOS +894 G > T and eNOS -786 T > C variants were genotyped using the novel multiplex PCR-RFLP and confirmed by DNA sequencing as well as snpBLAST. Allele frequencies of MTHFR 677 C > T and eNOS +894 G > T and eNOS -786 T > C were calculated using the Hardy Weinberg equation.

METHODS

The 114 healthy volunteers were recruited for this study, and their DNA was extracted. Primer pair was designed using Primer 3 Software version 0.4.0 and validated against the BLAST database. The primer specificity, functionality and annealing temperature were tested using uniplex PCR methods that were later combined into a single multiplex PCR. Restriction Fragment Length Polymorphism (RFLP) was performed in three separate tubes followed by agarose gel electrophoresis. PCR product residual was purified and sent for DNA sequencing.

RESULTS

The allele frequencies for MTHFR 677 C > T were 0.89 (C allele) and 0.11 (T allele); for eNOS +894 G > T, the allele frequencies were 0.58 (G allele) and 0.43 (T allele); and for eNOS -786 T > C, the allele frequencies were 0.87 (T allele) and 0.13 (C allele).

CONCLUSIONS

Our PCR-RFLP method is a simple, cost-effective and time-saving method. It can be used to successfully genotype subjects for the MTHFR 677 C > T and eNOS +894 G > T and eNOS -786 T > C variants simultaneously with 100% concordance from DNA sequencing data. This method can be routinely used for rapid investigation of the MTHFR 677 C > T and eNOS +894 G > T and eNOS -786 T > C variants.

MTHFR C677T polymorphism and its relationship to myocardial infarction in the Eastern Black Sea region of Turkey

BACKGROUND AND AIMS

An association of homozygous MTHFR 677T genotypes with elevated plasma homocysteine level has been documented, but results are still controversial. We aimed to investigate prevalence of the C677T polymorphism in patients with acute myocardial infarction (MI) in the Eastern Black Sea region of Turkey.

METHODS

We studied genomic DNA of 231 unrelated patients (aged 59 ± 13 years; 175 male, 56 female) with first anterior acute MI and 242 healthy controls (aged 54 ± 19 years; 182 male, 60 female) using real-time polymerase chain reaction kits for the MTHFR C677T mutation.

RESULTS

Prevalence of MTHFR C677T mutant genotype was 49.1% (CT: 45.8%, TT: 3.3%) in controls and 48.45% (CT: 38.5%, TT: 9.95%) in patients with acute MI. The TT mutation was more frequent in patients with acute MI than in controls (9.95 vs. 3.3%) (OR; 3.23, 95% CI; [1.34-8.05], p = 0.003).

CONCLUSIONS

The MTHFR gene homozygote TT mutation is a risk factor for patients with MI in the eastern Black Sea Turkish Population.

Variants within the nitric oxide synthase 1 gene are associated with stroke susceptibility

OBJECTIVE

Animal studies have allowed important insights into the role of the nitric oxide synthase (NOS) enzymes in atherosclerosis and hypertension, as well as in stroke. In this study we tested the hypothesis that the NOS1 and NOS3 genes, respectively encoding neuronal NOS (nNOS) and endothelial NOS (eNOS), influence stroke susceptibility and outcome after a stroke event.

METHODS

We conducted a case-control association study in 551 ischemic stroke patients and 530 controls to assess the role of NOS1 and NOS3 variants in stroke susceptibility. The same genes were tested for association with stroke outcome in a subset of 431 patients.

RESULTS

Four NOS1 single nucleotide polymorphisms (SNPs) (rs2293050, rs2139733, rs7308402 and rs1483757) and four haplotypes were significantly associated with stroke susceptibility after adjusting for demographic, clinical and life-style risk factors, and correcting for multiple testing using the false discovery rate (FDR) method (SNPs: 0.004<(uncorrected)P<0.007 and 0.036<FDR q<0.048; haplotypes: 0.001<(uncorrected)P<0.010 and 0.018<FDR q<0.032). NOS1 variants were not associated with stroke outcome. We did not find any evidence for a role of the NOS3 gene in stroke susceptibility or outcome.

CONCLUSION

Our results highlight NOS1 as a susceptibility factor for stroke, but do not corroborate previous NOS3 association findings with stroke risk. nNOS is known to play a major role in atherosclerosis development and in blood flow regulation, and it is plausible that its influence in stroke may be mediated through these two main clinical risk factors.

Evaluation of MTHFR C677T polymorphism in ischemic and hemorrhagic stroke patients. A case-control study in a Northern Indian population

OBJECTIVE

The present study was aimed to evaluate MTHFR C677T gene polymorphism in patients with ischemic stroke (IS) and intracerebral hemorrhage (ICH) and compare it with controls.

METHODS

207 patient with IS and 215 with CT/MRI proven ICH were included and compared with 188 healthy controls. The stroke risk factors, location of IS, its vascular territory and in ICH the location of hematoma were noted. MTHFR C677T polymorphism was studied by polymerase chain reaction.

RESULTS

Hypertension was present in 65.9% of ICH and 48.8% of IS. Other stroke risk factors were not significantly different. The frequency of the CC genotype in controls was 68.6%. CT in 28.7% and TT in 2.7%, whereas it was 75.3%, 20.5% and 4.2% in ICH and 66.2%, 39.4% and 2.4% respectively in IS. The frequency of these genotypes as well as allele frequency was not different in IS, ICH as compared to controls, however variant allele was more frequent in IS compared to ICH. Homocysteine level was higher in IS patients with variant genotype

INTERPRETATION

MTHFR C677T gene polymorphism was neither associated with hemorrhagic nor ischemic stroke. However raised homocysteine levels were found to be associated with MTHFRC677-TT genotype in IS patients.

TT Genotype of the Methylenetetrahydrofolate Reductase C677T Polymorphism is an Important Determinant for Homocysteine Levels in Multi-Ethnic Malaysian Ischaemic Stroke Patients

Introduction: The functional point mutation C677T in the methylenetetrahydrofolate reductase (MTHFR) gene, has been reported to contribute to hyperhomocysteinaemia which is a risk factor for atherothrombotic ischaemic strokes. This study evaluated the prevalence of the C677T polymorphism of the gene in Malaysian ischaemic stroke subjects of Malay, Chinese and Indian ethnicities, and its association with homocysteine levels (tHcy). Materials and Methods: A total of 292 subjects were recruited, comprising 150 ischaemic stroke patients and 142 control subjects who were age and sex matched. Plasma homocysteine, serum folate and vitamin B12 were measured in all subjects. Genotyping was carried out using PCR-RFLP. Results: The homocysteine levels were significantly higher (P = 0.001) in the stroke group (11.35 ± 2.75 μmol/L) compared to the control group (10.38 ± 2.79 μmol/L). The MTHFR C677T genotype distribution for the stroke group was 46%, 40% and 14%, respectively for CC, CT and TT genotypes and 59.9%, 33.8% and 6.3%, respectively for the control group. The genotype and allelic frequencies were significantly different between the 2 groups, with P = 0.02 and P = 0.004 respectively. No significant difference was seen in the genotype distribution inter-ethnically. An increasing tHcy was seen with every additional T allele, and the differences in the tHcy for the different genotypes were significant in both the control (P <0.001) and stroke groups (P <0.001). Conclusion: This study shows that TT genotype of the methylenetetrahydrofolate reductase C677T polymorphic gene is an important determinant for homocysteine levels in Malaysian ischaemic stroke patients. Key words: Homocysteine, Ischaemic stroke, Malaysia, MTHFR polymorphism

Association of the G894T polymorphism of the endothelial nitric oxide synthase gene with diabetic foot syndrome foot ulcer, diabetic complications, and comorbid vascular diseases: a Turkish case-control study

CONTEXT

There are controversial results and insufficient knowledge in the literature about the genetics of diabetes mellitus complications in the Turkish population and endothelial nitric oxide synthase (eNOS) gene polymorphisms may act as a potential modifier of diabetic vascular complications.

OBJECTIVE

The objective of this study was to determine the association between eNOS G894T polymorphisms and diabetes-related diseases.

DESIGN

A Turkish case-control study was designed.

SETTING

The study was carried out in the Ankara University Hospital.

PATIENTS OR OTHER PARTICIPANTS

Totally, 97 Turkish patients with diabetic foot ulcers and 102 controls were enrolled. Patients who had not received antimicrobial treatment in the preceding 6 months were included. Diabetic patients with hand and/or foot ulcers resulting from major trauma, such as road traffic accidents, were excluded.

MAIN OUTCOME MEASURE

The effect of eNOS gene polymorphisms on diabetic complications and comorbid diseases was measured.

RESULTS

Regarding eNOS G894T gene polymorphisms, 47.4% of the patients had GG (n = 46), 47.4% (n = 46) had GT, and 5.2% (n = 5) had TT alleles in the diabetes mellitus group, and 47.0% (n = 48), 41.2% (n = 42), and 11.8% (n = 12) had GG, GT, and TT alleles in the control group, respectively. There was no significant difference between the groups regarding the eNOS G894T gene allele ratios. Between groups with and without diabetic complications, a significant difference has only been found in the distribution of alleles in patients with comorbid atherosclerotic heart disease, whose GT-TT alleles were significantly higher than the GG alleles (p = 0.004).

CONCLUSION

G894T polymorphism of eNOS gene was not associated with foot ulcer and diabetic complications, except in the presence of atherosclerotic heart disease.

C677T polymorphism of the 5,10 MTHFR gene in young Mexican subjects with ST-elevation myocardial infarction

BACKGROUND AND AIMS

The C677T polymorphism of 5,10 methylenetetrahydrofolate reductase (MTHFR) gene has been associated with hypertension and coronary artery disease in several populations worldwide, but results are still controversial. The aim of this study was to examine the possible association of C677T polymorphism with ST-elevation myocardial infarction (STEMI) in young Mexican subjects.

METHODS

In a case-control study, 167 unrelated patients < or = 45 years of age with diagnosis of STEMI who were admitted to a cardiovascular intense care unit and 167 unrelated controls subjects matched by age and gender were recruited from January 2006 and June 2009. The C677T polymorphism was determined in all participants by a polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP).

RESULTS

There was no significant difference in the genotype distribution between groups (p = 0.69) or allele frequency (p = 0.40). There were independent factors for STEMI: smoking (OR 4.9, 95% CI 3.0-8.1, p = 0.001), hypertension (OR 1.8, 95% CI 1.0-3.3, p = 0.03), family history of atherothrombotic disease (OR 2.3, 95% CI 2.0-4.6, p = 0.02), and dyslipidemia (OR 3.2, 95% CI 1.8-5.6, p <0.001). Diabetes mellitus did not represent an independent risk factor for STEMI (OR 1.2, 95% CI 0.2-2.2, p = 0.82).

CONCLUSIONS

The TT genotype from the C677T of 5,10 MTHFR gene is not an independent risk factor for STEMI in the Mexican population. However, more studies are needed to determine the possible "protective effect" of the C677T polymorphism in our population.