Endothelial nitric oxide synthase exon 7 polymorphism, ischemic cerebrovascular disease, and carotid atheroma

Epithelial nitric oxide synthases (eNOS) 894 G < T polymorphism and diabetic nephropathy susceptibility: A meta-analysis

Objective

To investigate the epithelial nitric oxide synthases (eNOS) 894 G < T polymorphism and diabetic nephropathy (DN) susceptibility by pooling the open published data.

Methods

Studies relevant to eNOS 894 G < T polymorphism and DN susceptibility published in PubMed, EMBASE, Medline, CNKI, and Wanfang databases were systematically screened by using the text words of endothelial nitric oxide synthase, eNOS, NOS-3, G894T, rs179983, polymorphism, diabetic nephropathy, and DN. The correlation between eNOS 894 G < T polymorphism and DN susceptibility was demonstrated by odds ratio (OR) and corresponding 95% confidence interval (95% CI). The data were combined through fixed or random effect model according to statistical heterogeneity. The publication bias was assessed by Begg’s funnel plot and Egger’s line regression test.

Results

Twenty-six case-control studies relevant to eNOS 894 G < T polymorphism and DN susceptibility were identified by electronic searching of the related databases. Type 2 diabetes mellitus (T2MD) patients with T allele had increased susceptibility to DN compared with G allele under homologous gene model (TT vs GG) (OR = 1.40, 95% CI: 1.16–1.69, p = 0.001), dominant gene model (TT + GT) vs GG (OR = 1.61, 95% CI: 1.30–2.00, p = 0.000) and recessive gene model TT vs (GT + GG) (OR = 1.39, 95% CI: 1.16–1.66, p = 0.000). Publication bias was not statistically significant for homologous and recessive gene model.

Conclusion

Based on the present evidence, DN risk was increased in T2MD cases with T allele compared to G allele.

Endothelial Nitric Oxide Synthase (Glu298Asp) Polymorphism is Associated Significantly with Ischemic Stroke Presenting with Seizures and Altered Sensorium

Background

Endothelial nitric oxide synthase (eNOS) is an enzymatic marker whose genetic polymorphism might predispose to acute ischemic stroke (AIS) via vascular endothelial dysfunction. It has a potential role in atherosclerosis, making it a plausible risk factor for stroke. Prior studies have failed to prove a conclusive relationship between eNOS polymorphism and AIS.

Objective

The aim of this study is to find an association between the presence of eNOS polymorphism (Glu298Asp) and the risk of developing AIS.

Materials and Methods

We recruited 307 subjects including 153 AIS cases and 154 healthy controls. The eNOS (Glu298Asp) polymorphism was identified in EDTA blood by PCR amplification of the target region followed by restriction enzyme digestion, and genotyping on Agarose gel. GG, GT and TT genotypes were obtained. Statistical analysis was done using SPSS software version 20.

Results

A significant association was found between the presence of TT genotype and the risk of AIS (Odd's ratio (OR): 2.43, P-value = 0.038). There was no significant association between the TT genotype and the traditional stroke risk factors. However, the TT genotype was significantly associated with the presence of altered consciousness (OR: 5.27, 95% CI: 1.59-17.04, P-value = 0.003) and with the occurrence of seizures at presentation (OR: 7.98, 95% CI: 1.99-32.09, P-value = 0.007).

Conclusions

There is a significant association between the presence of eNOSpolymorphism (Glu298Asp) and the risk of AIS, and the TT genotype may predispose to a more severe initial presentation of ischemic stroke.

Genetic Variation and Hot Flashes: A Systematic Review

CONTEXT

Approximately 70% of women report experiencing vasomotor symptoms (VMS, hot flashes and/or night sweats). The etiology of VMS is not clearly understood but may include genetic factors.

EVIDENCE ACQUISITION

We searched PubMed and Embase in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance. We included studies on associations between genetic variation and VMS. We excluded studies focused on medication interventions or prevention or treatment of breast cancer.

EVIDENCE SYNTHESIS

Of 202 unique citations, 18 citations met the inclusion criteria. Study sample sizes ranged from 51 to 17 695. Eleven of the 18 studies had fewer than 500 participants; 2 studies had 1000 or more. Overall, statistically significant associations with VMS were found for variants in 14 of the 26 genes assessed in candidate gene studies. The cytochrome P450 family 1 subfamily A member 1 (CYP1B1) gene was the focus of the largest number (n = 7) of studies, but strength and statistical significance of associations of CYP1B1 variants with VMS were inconsistent. A genome-wide association study reported statistically significant associations between 14 single-nucleotide variants in the tachykinin receptor 3 gene and VMS. Heterogeneity across trials regarding VMS measurement methods and effect measures precluded quantitative meta-analysis; there were few studies of each specific genetic variant.

CONCLUSIONS

Genetic variants are associated with VMS. The associations are not limited to variations in sex-steroid metabolism genes. However, studies were few and future studies are needed to confirm and extend these findings.

Association of NOS3 gene polymorphisms with essential hypertension in Sudanese patients: a case control study

BACKGROUND

Essential hypertension (EH) is influenced by various environmental and genetic factors. Nitric oxide is important for the functional integrity of the vascular endothelium and is produced in endothelial cells by the enzyme endothelial nitric oxide synthase (eNOS). EH has a strong genetic component, and the NOS3 gene, which encodes eNOS, represents an interesting candidate for contribution to the phenotype. The most clinically relevant polymorphisms in the NOS3 gene are rs1799983 in exon 7 (encoding Glu298Asp), a variable number tandem repeat (VNTR) in intron 4, and rs2070744 (T-786C) in the promoter region. This study aims to investigate the association between these three polymorphisms in the NOS3 gene and EH in Sudanese patients.

METHODS

Hypertensive patients (n = 157) > 18 years of age with established hypertension from various hospitals in Khartoum, and controls (n = 85) > 18 years of age and with blood pressure measurements <140/90, were included in this case control study. Genotypes at the NOS3 variants were determined using TaqMan and polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analyses. Genotype and allele frequencies were compared between the two groups by χ² analysis, and differences were expressed as odds ratios with 95% confidence intervals (CIs). P values <0.05 were considered statistically significant.

RESULTS

The rs2070744 polymorphism in NOS3 was found to be associated with EH in the Sudanese population as the patients group had higher frequency of CC genotype compared with the controls (6.6% vs 6.1%, p = 0.02). Considering a dominant inheritance model, the frequency of TC + CC genotypes in patients was significantly higher than that in the control subjects (52.6% vs 34.1%, respectively; p < 0.01), with an odds ratio (95% CI) of 2.14 (1.23-3.74). In addition, the C allele was more frequent in the patients than the control group (29.6% vs 20%, p = 0.03, OR = 1.84 (1.15-2.93)). The c allele of intron 4 VNTR was reported in >1% of the Sudanese population under study.

CONCLUSION

The results of this study indicated that the rs2070744 polymorphism in NOS3 may be a genetic susceptibility factor for EH in the Sudanese population. The c allele of intron 4 VNTR is not rare in the Sudanese population.

Associations of the eNOS G894T gene polymorphism with target organ damage in children with newly diagnosed primary hypertension

BACKGROUND

The endothelial nitric oxide synthase (eNOS) G894T gene polymorphism is associated with the risk of primary hypertension (PH) and vascular complications in adults with PH.

METHODS

We explored the associations of the G894T polymorphism with 24-h ambulatory blood pressure, left ventricular mass (LVM), carotid intima media thickness (cIMT), urinary albumin excretion, oxidative stress and inflammatory parameters in 126 children with newly diagnosed PH and in 83 healthy children.

RESULTS

Among the 126 children with PH 92 (73%) had ambulatory hypertension and 34 (27%) had severe ambulatory hypertension. Left ventricular hypertrophy (LVH) was detected in 39 (31%) patients, cIMT of >2 standard deviation scores in 21 (16.6%) patients, albuminuria of >30 mg/24 h in 18 (14.3%) patients and metabolic syndrome (MS) in 22 (17.5%) patients. The frequency of the T allele was 52.4% in the PH group and 54.2% in the control group (not significant), and in both groups the frequency of the T allele was consistent with the Hardy-Weinberg equilibrium. Compared with G allele carriers, hypertensive T allele carriers had increased cIMT (p < 0.05) and more severe albuminuria (not significant, p = 0.1); there was no difference between the groups in hypertension severity and LVM. T and G allele distribution did not differ between patients with and without metabolic syndrome. No significant correlations between the assessed parameters and the eNOS G894T gene polymorphism were found in the controls, although T allele carriers tended to have an increased cIMT (p = 0.09).

CONCLUSION

The eNOS T allele is not more prevalent among hypertensive children than among healthy ones, but it is associated with early vascular damage in children with PH, independent of metabolic abnormalities. No associations between the eNOS G894T polymorphism and metabolic abnormalities were found.

G894T endothelial nitric oxide synthase polymorphism and ischemic stroke in Morocco

Nitric oxide plays a major role in the regulation of cerebral blood flow and loss of its function leads to alteration of the vascular relaxation given its central role in the physiology of the vascular system. G894T eNOS polymorphism could have adverse effects on the expression and activity of endothelial nitric oxide synthase, which can result in functional impairment of the endothelium and contribute to the development of ischemic stroke in the different models of transmission. In this study, genotyping with PCR-RFLP and HRM (high resolution melting) methods were conducted on 165 ischemic stroke patients as well as 182 controls. The goal here was to compare genotyping with PCR-RLFP primer sequences of eNOS gene (size < 300 bp) to HRM. Our data suggests a statistically significant association between G894T eNOS polymorphism and ischemic stroke in recessive, dominant and additive models with P < 0.05 and odds ratio of 2.68 (1.08-6.70), 1.78 (1.16-2.73), and 1.71 (1.21-2.43) respectively. In sum, although the sample size is relatively small, it suggests that G894T eNOS polymorphism could be a potentially important genetic marker of ischemic stroke in the Moroccan population. Future studies should be conducted in this direction taking into consideration the functional activity of eNOS.

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.

Methylenetetrahydrofolate reductase gene polymorphisms in patients with cerebral hemorrhage

Elevated plasma total homocysteine (HCY) level is a risk factor for coronary heart disease and ischemic stroke. We investigated relationships between polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, and plasma levels of HCY and folate in patients of Mongolian races who suffered from cerebral ischemia (CI, n = 42) or cerebral hemorrhage (CH, n = 20) and in the 24 age-matched controls. The incidences of both homozygous and heterozygous MTHFR gene mutations in CI (26 and 43%) and in CH (25 and 60%) were significantly higher than those in the controls (8 and 25%). Homozygous MTHFR gene mutation was associated with reduced plasma folate levels, but not with increased plasma HCY levels. Among the subjects with homozygous MTHFR gene mutation, plasma folate levels in CH was significantly lower than those in CI and controls. MTHFR gene mutation in CH was found to be as common as that in CI and was associated with reduced plasma folate levels in the both. In homozygous MTHFR gene mutation, the plasma folate level was profoundly reduced in CH as compared with CI and controls, suggesting that subjects with low plasma folate levels have a predisposition to intracerebral bleeding.

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.

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.

eNOS [Glu298Asp] polymorphism, erectile function and ocular pressure in type 2 diabetes

BACKGROUND

  Imbalance in nitric oxide (NO), an atheroprotective vasodilator, is associated with endothelial dysfunction, cardiovascular diseases (CVD) and diabetic complications. Various endothelial NO synthase (eNOS) polymorphisms may affect NO bioavailability, thereby promoting adverse cardiovascular milieu.

MATERIALS AND METHODS

  To analyze glucose homeostasis, cardiometabolic phenotype, and micro- and macroangiopathies associated with eNOS G894T gene polymorphism in type 2 diabetes (T2DM). 210 T2DM outpatients (mean age (1SD) 70 (12); diabetes duration 19 (9) years; males:females 64:36%; metabolic syndrome 87%) had insulin sensitivity and b-cell function modelled with HOMA, alongside routine laboratory and endothelin measurements.

RESULTS

  GG, GT and TT genotypes represented 48% (n = 100), 39% (n = 83) and 13% (n = 27). Overall microangiopathy (retinopathy, neuropathy and/or nephropathy) was present in 74%, and overall macroangiopathy (CAD, PAD and/or TIA/stroke) in 45%. The TT genotype did not translate into a more severe vascular phenotype, as TT patients carrying the proposed risk genotype did not suffer a higher rate of micro- and macrovascular complications. On the other hand, erectile dysfunction, present in 60% of males (n = 135), was much more prevalent in TT males: 57% [GG & GT] vs. 93% in TT (p 0.0088). Ocular hypertension/glaucoma frequency (18% of the whole group) was also markedly different, albeit in opposing directions, between eNOS G894T gene polymorphism subgroups: 21% [GG & GT] vs. 0% prevalence (TT; p 0.0057).

CONCLUSIONS

  eNOS G894T gene polymorphism in homozygous TT carriers translates into opposing effects on erectile function (detrimental) and ocular hypertension/glaucoma (protective) in T2DM, without affecting glucose homeostasis determinants or the presence of micro- and macrovascular complications.

Pharmacogenetic association of NOS3 variants with cardiovascular disease in patients with hypertension: the GenHAT study

Nitric oxide synthase 3 (NOS3) catalyzes production of NO in the endothelium and may play a role in cardiovascular disease (CVD). We assessed the pharmacogenetic associations of three NOS3 polymorphisms and three antihypertensive drugs with CVD outcomes. Hypertensive subjects (n = 30,280) from a multi-center, double-blind clinical trial were randomized to chlorthalidone, amlodipine, or lisinopril treatment (mean follow up, 4.9 years). Outcomes included coronary heart disease (CHD: fatal CHD and nonfatal myocardial infarction); stroke; heart failure (fatal, requiring hospitalization, or outpatient treatment); all-cause mortality; and end-stage renal disease (ESRD). Main effects of NOS3 variants on outcome and genotype-treatment interactions were tested. For NOS3 −690 C>T (rs3918226), a higher hazard ratio (HR) was found in minor allele carriers for CHD (CC = 1.00, CT+TT = 1.12 (95% confidence interval (CI) = 1.00–1.26), P = 0.048). For NOS3 −922 A>G (rs1800779), a higher HR was found in minor allele carriers for heart failure (AA = 1.00, AG+GG = 1.10 (CI = 1.00–1.21), P = 0.046). Significant pharmacogenetic findings were observed for stroke and all-cause mortality. For −690 C>T, a lower HR was observed for stroke in minor allele carriers when treated with amlodipine versus lisinopril (CC = 0.85 (CI = 0.73–0.99), CT+TT = 0.49 (CI = 0.31–0.80), P = 0.04). For glu298asp G>T (rs1799983), a lower HR was observed for all-cause mortality in minor allele carriers when treated with amlodipine versus lisinopril (GG = 1.01 (CI = 0.91–1.13), GT+TT = 0.85 (CI = 0.75–0.97), P = 0.04). We observed significant associations with NOS3 variants and CHD and heart failure and significant pharmacogenetic effects for stroke and all cause mortality. This suggests that NOS3 variants may potentially provide useful clinical information with respect to treatment decisions in the future.

Effect of exercise training on the cardiovascular and biochemical parameters in women with eNOS gene polymorphism

CONTEXT

Presence of endothelial nitric oxide synthase (eNOS) gene polymorphism has been associated with cardiovascular disease (CVD) whereas exercise training (EX) promotes beneficial effects on CVD which is related to increased nitric oxide levels (NO).

OBJECTIVE

To evaluate if women with eNOS gene polymorphism at position-G894T would be less responsive to EX than those who did not carry T allele.

METHODS

Women were trained 3 days/week, 40 minutes session during 6 months. Cardio-biochemical parameters and genetic analysis were performed in a double-blind fashion.

RESULTS

Plasma NOx- levels were similar in both groups at baseline (GG genotype: 18.44±3.28 μM) and (GT+TT genotype: 17.19±2.43 μM) and after EX (GG: 29.20±4.33 and GT+TT: 27.38±3.12 μM). A decrease in blood pressure was also observed in both groups.

DISCUSSION AND CONCLUSION

The presence of eNOS polymorphism does not affect the beneficial effects of EX in women.

Polymorphisms of genes in nitric oxide-forming pathway associated with ischemic stroke in Chinese Han population

AIM

To investigate the association of polymorphisms in four critical genes implicated in the NO-forming pathway with ischemic stroke (IS) in a Chinese Han population.

METHODS

DNA samples of 558 IS patients and 557 healthy controls from Chinese Han population were genotyped using the Taqman(TM) 7900HT Sequence Detection System. Six SNPs (rs841, rs1049255, rs2297518, rs1799983, rs2020744, rs4673) of the 4 related genes (eNOS, iNOS, GCH1, and CYBA) in the NO forming pathway were analyzed using the SPSS 13.0 software package for Windows.

RESULTS

One SNP located in the intron of GCH1 (rs841) was associated with IS independent of the traditional cardiovascular risk factors in co-dominant and dominant models (P=0.003, q=0.027; P=0.00006, q=0.0108; respectively). Moreover, the combination of rs1049255 CC+CT and rs841 GA+AA genotypes was associated with significantly higher risk for IS after adjustments (OR=1.73, 95% CI: 1.27-2.35, P<0.0001, q<0.0001).

CONCLUSION

The data suggest that genetic variants within the NO-forming pathway alter susceptibility to IS in Chinese Han population. Replication of the present results in other independent cohorts is warranted.

Effects of human endothelial gene polymorphisms on cellular responses to hyperglycaemia: role of NOS3 (Glu298Asp) and ACE (I/D) polymorphisms

The functional relevance of NOS3 and ACE genetic variations to endothelial cell function is largely unstudied. Here we tested the functional relevance of the NOS3 (Glu298Asp) polymorphism and ACE (I/D) polymorphism in endothelial cells in vitro. Our hypothesis was that these genetic polymorphisms alter endothelial cell sensitivity to glucose and 3-nitrotyrosine (3NT). Genotyped HUVECs were incubated with glucose, free 3NT or a combination of these two toxicants. Significant differences in glucose-induced cell death and free 3NT-induced cell death were observed among the NOS3 genotypes. Combined glucose/3NT caused increased toxicity among the NOS3 genotypes. No differences were observed among the ACE genotypes in their responses to glucose/3NT. These data demonstrate that the NOS3 genotype may be an important predictor of, or be mechanistically involved in, endothelial vulnerability, whereas the ACE I/D genotype is apparently less important. Thus this NOS3 genetic variation may play a role in vulnerability to endothelium-dependent diabetic vascular complications.

Association of transforming growth factor-β1 gene C-509T and T869C polymorphisms with atherosclerotic cerebral infarction in the Chinese: a case-control study

Background

Transforming growth factor-β1 (TGF-β1) is a multifunctional cytokine involved in inflammation and pathogenesis of atherosclerosis. There is scant information on the relation between variations within the TGF-β1 gene polymorphisms and risks of ischemic cerebrovascular diseases. Therefore, this case-controlled study was carried out to investigate the possible association of the TGF-β1 gene C-509T and T869C polymorphisms, and their combined genotypes with the risk of atherosclerotic cerebral infarction (CI) in the Chinese population.

Results

We recruited 164 CI patients and 167 healthy control subjects who were frequency-matched for age and gender. The frequencies of the -509TT genotype and T allele gene were significantly higher in the CI group (P = 0.007, P = 0.006). The frequencies of +869CC genotype and C allele were higher in the CI group (P = 0.002, P = 0.004). In the CI group, the individuals with -509TT genotype had a significantly higher level of plasma triglyceride (TG) (P = 0.017). +869CC genotype correlated significantly with higher level of plasma low density lipoprotein cholesterol (LDL-c) in the CI group (P = 0.015). With haplotype analysis, the frequency of the -509T/+869C combined genotype was significantly higher in the CI group than in controls (P < 0.001).

Conclusions

Our study suggests that C-509T and T869C gene polymorphisms in TGF-β1 may be a critical risk factor of genetic susceptibility to CI in the Chinese population.

VNTR polymorphism in intron 4 of the eNOS gene and the risk of ischemic stroke in a South Indian population

Ischemic stroke is a leading cause of death throughout the world. An increasing number of studies have suggested that genetic factors are important in the stroke risk. The aim of our study was to investigate whether the Variable Number of Tandem Repeats (VNTR) polymorphism in intron 4 of the endothelial nitric oxide synthase (eNOS) gene is associated with ischemic stroke in a South Indian population. 357 patients and 283 controls were enrolled in this case-control study. The ischemic stroke patients were classified according to TOAST classification. The eNOS gene polymorphism was determined by polymerase chain reaction-polyacrylamide gel electrophoresis. The genotypes were confirmed by sequencing the PCR products. There were significant differences in the genotype and allele frequencies of eNOS polymorphism between the patients with ischemic stroke and healthy controls (p=0.000). Multiple logistic regression analysis with forward stepwise selection using the potential confounders (sex, age, diabetes, hypertension, smoking and alcoholism) and eNOS gene variant revealed that the VNTR polymorphism in intron 4 of the eNOS gene is significantly [adjusted odds ratio=6.23, 95%CI (4.30-9.29), p=0.000] associated with ischemic stroke in the South Indian population from Andhra Pradesh. We did not find significant association of this polymorphism with any specific stroke subtype. Further hypertensives bearing 4a allele in high frequency are more predisposed to stroke.

Endothelial nitric oxide synthase Glu298Asp, 4b/a, and -786T>C gene polymorphisms and the risk of ischemic stroke

BACKGROUND AND PURPOSE

Endothelial nitric oxide synthase (eNOS) gene polymorphisms were associated with reduced NO production, and were evaluated as risk factors for ischemic stroke (IS). We investigated the association between eNOS gene -786T>C (promoter), 27-bp repeat 4b/4a (intron 4), and Glu298Asp (exon 7) polymorphisms with IS in 329 IS patients and 444 controls.

MATERIALS AND METHODS

Glu298Asp and -786T>C genotyping was done by PCR-RFLP, 4b/4a was assessed by PCR-ASA. The contribution of eNOS polymorphisms to IS was analyzed by haplotype and multivariate regression analysis.

RESULTS

Higher frequency of 298Asp allele was seen in IS patients (P = 1.2 x 10(-10)), which remained independently associated with IS on multivariate analysis after controlling for traditional cerebrovascular risk factors. Allele and genotype distribution of 4b/4a and -786T>C polymorphisms were comparable between patient and controls. Significantly higher prevalence of 298Asp/4b/-786T and 298Asp/4b/-786C haplotypes were seen in IS cases, thus conferring a disease susceptibility nature to these haplotypes. Multivariate regression analysis confirmed the association of 298Asp/4b/-786T and 298Asp/4b/-786C haplotypes, and in addition identified 298Asp/4a/-786T haplotype to be independently associated with IS, after controlling for traditional cerebrovascular risk factors.

CONCLUSIONS

Genetic variation at the eNOS locus represent genetic risk factor for increased susceptibility to IS.

Haplotype Analysis of the CYP8A1 Gene Associated With Myocardial Infarction

Objective: The aim of this study was to assess the association between the human CYP8A1 gene and myocardial infarction (MI) in Chinese people. Methods: 210 MI patients and 206 age-matched controls were genotyped and constructed haplotypes for 3 SNPs [3982C>T (rs5602), C1117A (rs5629), C251T (rs454-98106)] of the human CYP8A1 gene. Results: The CC genotype of rs5629 was more frequently in MI patients than in control subjects (P = .030). The frequency of the A-C-T haplotype was significantly higher in MI patients than in control subjects (P =.001). The frequency of the C-T-T haplotype was significantly lower in MI patients than in control subjects (P= .011). Conclusions: The present results indicate that MI is associated with the CC genotype of rs5629 in the human CYP8A1 gene. The A-C-T haplotype appears to be a useful genetic marker and the C-T-T haplotype might be a protective factor of MI in Chinese people.

Stroke genetics--focus on PDE4D gene

Stroke is a complex disease comprising of a heterogenous group of disorders with multiple risk factors. Genetic predisposition to stroke does occur and has been documented in both animal models and human beings. However, a precise definition of genetic factors responsible for stroke is still lacking because research into the genetic basis of stroke presents some unique challenges. More commonly it seems to be a multifactorial polygenic disorder. Mutations in some candidate genes are likely to predispose or give protection against stroke. Several mutations in various genes have been found to be associated with stroke. However, we have a long way to go before we can accurately pinpoint the genes responsible for multifactorial stroke. Recently, the deCODE group has suggested an association between the phosphodiesterase 4D (PDE4D) gene and the risk of stroke in Icelanders. PDE4D is the first putative gene associated with common polygenic stroke. Specific variants of this gene have been shown to present risk for ischemic stroke in Icelanders. Replication studies in non-Icelanders have yielded variable results. There may be obvious racial differences in the prevalence of these mutations but still many questions remain unsolved regarding the role of PDE4D in stroke development.

Platelet nitric oxide production and IR: relation with obesity and hypertriglyceridemia

BACKGROUND AND AIM

Three NOS isoforms are responsible for nitric oxide production in various tissues. Endothelial constitutive NOS is expressed in vascular endothelium and in platelets, contributing to vascular tone regulation and platelet aggregation. The aim of the present work was to examine eNOS polymorphism, to find a correlation with platelet NO production and degree of insulin resistance (IR) in non-diabetic subjects and in patients affected by type 2 diabetes.

METHODS AND RESULTS

Seventy-one non-diabetic subjects and 37 patients affected by Type 2 diabetes were recruited. The subjects were subdivided into 3 groups as cut-off for the definition of an insulin resistant state: IR non-diabetic subjects, insulin sensitive subjects, and insulin-resistant patients affected by Type 2 diabetes. Plasma glyco-metabolic parameters, platelet nitric oxide production, endothelial nitric oxide synthase (eNOS) gene polymorphism were measured in all subjects enrolled. Significant differences between groups were found in BMI, fasting glycaemia, fructosamine and HbA(1c), triglycerides and HDL cholesterol levels. Evaluating all the subjects, platelet NO production was significantly related with BMI, waist circumference, and triglycerides concentrations, thus suggesting an association between increased platelet NO production, obesity and hypertriglyceridemia, independent of the degree of insulin-resistance.

CONCLUSION

The modified platelet NO synthesis does not seem to be due to eNOS Glu298Asp polymorphism, while it can be hypothesized that it is caused by an iNOS induction, present in obesity, hypertriglyceridemia and in type 2 diabetes.

Association of a 27-bp repeat polymorphism in intron 4 of endothelial constitutive nitric oxide synthase gene with myocardial infarction in Tunisian patients

BACKGROUND

Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) mediates endothelium-dependent vasodilatation and antithrombotic action. Controversial results regarding the association of eNOS gene (NOS3) polymorphisms with myocardial infarction (MI) have been reported. In the present study, we examined a possible association between a 27-base pair (bp) repeat polymorphism in intron 4 of the NOS3 gene and MI in a subgroup of the Tunisian population.

METHODS

A total of 310 Tunisian patients with MI and 250 healthy controls were included in the study. The NOS3 gene intron 4a4b variable number of tandem repeats polymorphism was analyzed by PCR.

RESULTS

A significant difference in genotype distribution and allele frequency was observed between patients and controls. Patients with MI had a frequency of 4.8% for the 4a4a genotype, 33.9% for the 4a4b genotype and 61.3% for the 4b4b genotype. Controls had a frequency of only 1.6% for the 4a4a genotype, 24.4% for the 4a4b genotype and 74.0% for the 4b4b genotype (chi2=11.81, p=0.003). The MI patient group showed a significant higher frequency of the 4a allele compared to controls (0.218 vs. 0.139; chi2=5.81, p=0.01).

CONCLUSIONS

In the present study, a significant association between the NOS34a/4b gene polymorphism (presence of 4a allele) and MI in the Tunisian population was found.

Genes, endothelial function and cerebral small vessel disease in man

Cerebral small vessel disease results from ischaemia in the perforating arteries supplying the white matter and deep grey matter nuclei. It results in both focal lacunar infarction and more diffuse areas of chronic ischaemia (leukoaraiosis). Two subtypes may exist. One subtype (isolated lacunar infarction) is associated with single or a few larger lacunar infarcts without leukoaraiosis, and may result from microatheroma in the larger perforating arteries. The second subtype (ischaemic leukoaraiosis) results in multiple small lacunar infarcts with leukoaraiosis secondary to a diffuse arteriopathy affecting the smaller perforating arteries, usually occurring in the presence of hypertension. In this subtype, chronic hypoperfusion and impaired cerebral autoregulation have been reported. A number of lines of evidence support a pathogenic role of endothelial activation and dysfunction. Genetic predisposition has also been implicated. Associations with genes involved in endothelial function, including those regulating the renin-angiotensin system, endothelial nitric oxide and homocysteine levels, have been reported. However, not all results have been replicated and there are few robust replicable associations. Larger studies are required to determine definitively which associations represent important risk factors.

Biochemical consequences of the NOS3 Glu298Asp variation in human endothelium: altered caveolar localization and impaired response to shear

Human endothelial nitric oxide synthase (NOS3) gene polymorphism at Exon 7 (Glu298Asp) has been linked to vascular endothelial dysfunction, but the mechanisms are not defined. Shear is a key modulator of NOS3 function in vivo and association with caveolae is important for the control of NOS3 protein activity. Here we tested the hypothesis that altered enrichment of NOS3 in the caveolar membrane defines Glu298Asp genotype-specific responses and NOS3 activity. Basal caveolar membrane enrichment was carried out to quantitate the NOS3 enrichment in caveolae. Cells were subjected to shear and NOS3 protein levels, phosphorylation, enzyme function were investigated. Variant genotypes had lower NOx production pre- and post-shear, but no genotype-dependent alterations in pNOS3 were observed. Asp variants had significantly lower NOS3 enrichment in the caveolar membrane fraction. Further, immunoprecipitation studies demonstrated that Asp variants had substantially less NOS3/Cav-1 association (approximately 40%) during static conditions. Furthermore, acute shear causes impaired NOS3/Cav-1 dissociation in Asp variants. The results from immunoprecipitation studies were in complete agreement with caveolar membrane preparation findings. Collectively, these data demonstrate functional consequences of the Glu298Asp NOS3 variation and further define disruption of NOS3 caveolar localization and shear-induced mobilization as the primary mechanism responsible for these differences.

Sténoses athéroscléreuses des artères carotides internes

Atherosclerotic carotid stenosis is a risk factor for stroke and other vascular events. Preventive medical treatment is based on the elimination of risk factors and the use of antithrombotic drugs. Surgery remains the standard revascularization treatment. The benefits of carotid surgery are especially important for severe (> or = 70%) symptomatic carotid stenosis. The benefits of surgery for moderate (> or =60%) asymptomatic stenosis or for moderate (50-69%) symptomatic stenosis are slight, particularly in women. The treatment decision requires consideration of individual factors to optimize the risk/benefit ratio.

The glu298asp polymorphism in the nitric oxide synthase 3 gene is associated with the risk of ischemic stroke in two large independent case–control studies

The search for genes involved in the pathogenesis of stroke has been highlighted as a field of needs. We followed the concept, that stroke represents a complex genetic disorder, and analyzed the contribution of 106 informative single nucleotide polymorphisms (SNPs) from 63 candidate genes for cardiovascular diseases for the risk of stroke. We conducted two independent case-control studies in two different German regions and recruited a total of 1,901 hospitalized stroke cases and 1,747 regional population controls. The smaller of both studies was used as the replication study. Multiplex PCR in combination with allele-specific hybridization was used for genotype determination. Descriptive statistics, permutations and multivariable logistic regression were used in the analyses. After permutation testing 5 SNPs, located in the nitric oxide synthase 3, the alpha 2 integrin, the interleukin 13, the selectin P and the chemokine receptor 2 genes, had a significant allele difference between cases and controls in the larger study. For one of these SNPs, the glu298asp polymorphism in the nitric oxide synthase 3 gene, an association with ischemic stroke was replicated in the second study and also in a combined analysis of both studies. This association was independent of age, gender, hypertension, diabetes and hypercholesterolemia in both studies. Using large sample sizes and a replication study approach, we found evidence for a role of a polymorphism in the nitric oxide synthase 3 gene in stroke onset.

Endothelial nitric oxide synthase gene polymorphisms and cardiovascular disease: a HuGE review

This review examines the association of a subset of endothelial nitric oxide synthase gene (NOS3) polymorphisms (Glu298Asp, intron 4, and -786T>C) with cardiovascular disease. The Glu298Asp polymorphism within exon 7 is the only common nonsynonymous variant. The variants have been associated with low plasma nitric oxide concentrations and reduced vascular reactivity; difficulties in measuring those phenotypes means that their functional role remains unclear. A large meta-analysis of NOS3 polymorphisms in coronary heart disease revealed per-allele odds ratios of 1.17 (95% confidence interval: 1.07, 1.28) for Glu298Asp, 1.17 (95% confidence interval: 1.07, 1.28) for -786T>C, and 1.12 (95% confidence interval: 1.01, 1.24) for intron 4. However, there was evidence that small studies with more striking results could affect the associations of the Glu298Asp and -786T>C polymorphisms with coronary heart disease. Associations of NOS3 polymorphisms with hypertension, preeclampsia, stroke, and diabetes remain uncertain. To date, no reliable gene-gene or gene-environmental interactions have been described. Use of these variants in predictive testing is unlikely to be useful, although the population attributable fraction could be substantial if the modest associations are causal. The need for large-scale genetic association studies using tagging polymorphisms is warranted to confirm or refute a role of the NOS3 gene in coronary heart disease.

Endothelial nitric oxide gene T-786C polymorphism and subarachnoid hemorrhage in Korean population

We aimed to elucidate whether the eNOS T-786C mutant allele is implicated in subarachnoid hemorrhage (SAH) susceptibility or vasospasm after SAH, and whether the mutant allele is differentially expressed in those with small and large ruptured aneurysms in Korean population. 136 consecutive patients diagnosed with aneurismal SAH and 113 controls were recruited. Polymerase chain reaction and direct sequencing of both strands were performed to determine genotypes with respect to the eNOS T-786C mutation. No significant difference was found between cases and controls with respect to the distributions of the two eNOS T-786C single nucleotide polymorphism (SNP) genotypes. No significant differences in the distributions of the eNOS T-786C SNP genotypes were found with regard to the sizes of ruptured aneurysms or the occurrence of vasospasm after SAH. Multiple logistic regression analysis after controlling for age and sex showed the eNOS T-786C SNP T/C geno-type was independently associated with an unfavorable outcome (GOS grade 3-5) of SAH (Exp (beta)=4.27, 95% CI 1.131-16.108, p=0.032). In conclusion, the eNOS T-786C mutation was not found to be associated with either a susceptibility to SAH or vasospasm after SAH, or with aneurysm size in Korean population. The eNOS T-786C SNP T/C genotype could be used as a prognostic marker in individuals with SAH.

The role of endothelial nitric oxide synthase (eNOS) genetic variants in European patients with intracranial aneurysms

The endothelial nitric oxide synthase (eNOS) gene harbors three well-characterized genetic variants, which have been reported to be associated with various vascular diseases. Recently, conflicting results have been published relating to the role of these genetic variants in the pathogenesis of intracranial aneurysms (IA). Therefore, we analyzed these variants in a large European population of IA patients and controls. In all, 142 patients with IA and 190 controls were enrolled in our study. The -786T>C and 894G>T single-nucleotide polymorphisms (SNPs) were analyzed by direct sequencing of the corresponding sections in the genomic DNA. A variable number tandem repeat (VNTR) located in intron 4 of the gene and consisting of either four or five 27-base pair (bp) repeats was analyzed by polymerase chain reaction amplification and electrophoresis using ALF sequencertrade mark equipment. Genotype and allele frequencies were determined, and the frequencies in cases and controls were compared. In addition, haplotypes were constructed. There were no deviations from Hardy-Weinberg equilibrium. Genotype and allele frequencies did not differ significantly between cases and controls in any sample group or after stratification for multiple IA or aneurysm size. No single haplotype was significantly associated with the phenotype of an IA. The -786T>C, 894G>T, and 27-bp VNTR genetic variants of the eNOS gene are not associated with IA in the European population.

Coronary artery spasm and the polymorphisms of the endothelial nitric oxide synthase gene

BACKGROUND

Coronary artery spasm plays an important role in the pathogenesis of vasospastic angina, and contributes to the development of several acute coronary syndromes. Endothelial nitric oxide synthase (ecNOS) catalyzes the synthesis of nitric oxide, which regulates vascular tone, and may be related to coronary vasospasm. The present study investigated whether coronary spasm is related to particular polymorphisms of the ecNOS gene.

METHODS AND RESULTS

Spasm provocation by serial infusions of acetylcholine was performed on 165 patients who were clinically suspected of having angina. In both study patients and healthy controls (n=400), genomic polymorphisms of the ecNOS gene were determined by using polymerase chain reaction. Quantitative luminal diameter measurements of the 3 major coronary arteries were initially obtained before and after acetylcholine injection, and then after isosorbide dinitrate injection, by using a computer-assisted analysis system. Logistic multiple regression analysis identified the a/a or a/b genotype in intron 4 of ecNOS (NOS4a: p=0.0431, odds ratio (OR) 2.43) and diabetes mellitus (p=0.0060, OR 4.88) as significant predictors of coronary spasm. In the patients with NOS4a, both the induced and spontaneous contractions were augmented.

CONCLUSION

The present study results indicated that NOS4a could be a good marker for coronary artery spasm.

Endothelial nitric oxide synthase G894T gene polymorphism in Chilean subjects with coronary artery disease and controls

BACKGROUND

Nitric oxide (NO) from the endothelium, produced by oxidation of l-arginine to L-citruline for the action at the endothelial nitric oxide synthase (eNOS), is considered an important atheroprotective factor. The Glu298Asp (G894T) polymorphic variant of the eNOS gene has been implicated in the development of coronary artery disease (CAD). We investigated the association between occurrence of CAD documented by angiography and the G894T polymorphism of the NOS3 gene in Chilean individuals.

METHODS

A total of 112 unrelated patients with diagnosis of CAD and 72 controls were included in this study. G894T gene polymorphism was analyzed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP).

RESULTS

The frequency of TT homozygous genotype for G894T polymorphism was 7% in CAD patients and 1% in the control group. However, the genotype distribution and allele frequencies were not significantly different between CAD and control subjects (P>0.05). Moreover, the odds ratio for CAD associated with the T variant failed to reach statistical significance (OR=1.5; 95% CI: 0.87-2.59, P>0.05).

CONCLUSION

These findings suggest that the G894T polymorphism of the eNOS gene was not associated with CAD in Chilean individuals.