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

Association of Single-Nucleotide Polymorphisms Rs2779249 (chr17:26128581 C>A) and Rs rs2297518 (chr17: chr17:27769571 G>A) of the NOS2 Gene with Tension-Type Headache and Arterial Hypertension Overlap Syndrome in Eastern Siberia

Inducible nitric oxide (NO) synthase (iNOS), encoded by the NOS2 gene, promotes the generation of high levels of NO to combat harmful environmental influences in a wide range of cells. iNOS can cause adverse effects, such as falling blood pressure, if overexpressed. Thus, according to some data, this enzyme is an important precursor of arterial hypertension (AH) and tension-type headache (TTH), which are the most common multifactorial diseases in adults. The purpose of this study was to investigate the association of rs2779249 (chr17:26128581 C>A) and rs2297518 (chr17: chr17:27769571 G>A) of the NOS2 gene with TTH and AH overlap syndrome (OS) in Caucasians in Eastern Siberia. The sample size was 91 participants: the first group-30 patients with OS; the second group-30 patients AH; and the third group-31 healthy volunteers. RT-PCR was used for the determination of alleles and genotypes of the SNPs rs2779249 and rs2297518 of the NOS2 gene in all groups of participants. We showed that the frequency of allele A was significantly higher among patients with AH compared with healthy volunteers (p-value < 0.05). The frequency of the heterozygous genotype CA of rs2779249 was higher in the first group vs. the control (p-value = 0.03), and in the second group vs. the control (p-value = 0.045). The frequency of the heterozygous genotype GA of rs2297518 was higher in the first group vs. the control (p-value = 0.035), and in the second group vs. the control (p-value = 0.001). The allele A of rs2779249 was associated with OS (OR = 3.17 [95% CI: 1.31-7.67], p-value = 0.009) and AH (OR = 2.94 [95% CI: 1.21-7.15], p-value = 0.015) risks compared with the control. The minor allele A of rs2297518 was associated with OS (OR = 4.0 [95% CI: 0.96-16.61], p-value = 0.035) and AH (OR = 8.17 [95% CI: 2.03-32.79], p-value = 0.001) risks compared with the control. Therefore, our pilot study demonstrated that the SNPs rs2779249 and rs229718 of the NOS2 gene could be promising genetic biomarkers for this OS risk in Caucasians from Eastern Siberia.

Genetic Factors of Nitric Oxide's System in Psychoneurologic Disorders

According to the recent data, nitric oxide (NO) is a chemical messenger that mediates functions such as vasodilation and neurotransmission, as well as displaying antimicrobial and antitumoral activities. NO has been implicated in the neurotoxicity associated with stroke and neurodegenerative diseases; neural regulation of smooth muscle, including peristalsis; and penile erections. We searched for full-text English publications from the past 15 years in Pubmed and SNPedia databases using keywords and combined word searches (nitric oxide, single nucleotide variants, single nucleotide polymorphisms, genes). In addition, earlier publications of historical interest were included in the review. In our review, we have summarized information regarding all NOS1, NOS2, NOS3, and NOS1AP single nucleotide variants (SNVs) involved in the development of mental disorders and neurological diseases/conditions. The results of the studies we have discussed in this review are contradictory, which might be due to different designs of the studies, small sample sizes in some of them, and different social and geographical characteristics. However, the contribution of genetic and environmental factors has been understudied, which makes this issue increasingly important for researchers as the understanding of these mechanisms can support a search for new approaches to pathogenetic and disease-modifying treatment.

GCH1 (rs841) polymorphism in the nitric oxide-forming pathway has protective effects on obstructive sleep apnea

Several studies have recently investigated the contribution of genetic factors in obstructive sleep apnea (OSA). Patients with OSA suffer from a reduction in nitric oxide (NO) serum level. This study investigated rs841, A930G p22phox, and rs1799983 polymorphisms in three critical genes involved in NO formation. A total of 94 patients with OSA and 100 healthy controls were enrolled into the study. Results showed there was no association between rs841, A930G p22phox and rs1799983 polymorphism and the risk of OSA (P = 0.51, P = 0.4 and P = 0.33, respectively). Moreover, rs841 GA genotype had a reverse relationship with the severity of OSA (P = 0.005). On the other hand, rs841 GA and A930G p22phox AA genotypes had a protective effect on daytime sleepiness in OSA patients (P = 0.01and P = 0.02, respectively). Additionally, the combination of rs841 and A930G p22phox (AG/AG and AG/AA) genotypes was significantly associated with a reduction in daytime sleepiness in OSA patients (P = 0.03 and P = 0.03, respectively). According to the results of our study, GA genotype of rs841 and GA/AA genotypes of A930G p22phox polymorphisms significantly reduced the severity of the problem and daytime sleepiness in OSA patients.

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.

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.