No association between Glu/Asp polymorphism of NOS3 gene and ischemic stroke

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.

Protective role of 27bp repeat polymorphism in intron 4 of eNOS gene in lacunar infarction

Association of the three potential endothelial nitric oxide synthase gene (eNOS) polymorphisms (T-786C in promoter region, G894T in exon 7 and tandem 27-bp repeats in intron 4) with an increased risk of lacunar infarction (LI) were investigated. Genotypes of 70 patients and 81 healthy controls were determined through PCR with or without RFLP. Flow-mediated dilatation (FMD) was performed to assess endothelial-dependent vasodilatation, whereas the endothelial-independent vasodilatation was assessed with nitroglycerin (NTG). Genotype distribution was significantly different between LI patients and controls for intron 4aa (alleles for four repeats), genotype frequency being 1.4% and 16.0%, respectively (odds ratio for additive effect, 0.47; 95% CI, 0.28-0.81; p=0.006). Haplotypes with the intron 4aa polymorphism were significantly higher in controls when compared with the LI group (p=0.001). Diminished FMD but normal NTG response confirmed that patients with LI have generalized endothelial dysfunction. Intron 4aa genotype of eNOS gene seems to be protective for isolated LI and the effect was potentiated by the absence of 786C polymorphism in any allele of the promoter region.

Genetic polymorphisms for the study of multifactorial stroke

Single-gene disorders explain only a minority of stroke cases. Stroke represents a complex trait, which is usually assumed to be polygenic. On this topic, the role of a wide number of candidate genes has been investigated in stroke through association studies, with controversial results. Therefore, it is difficult for the clinician to establish the validity and the level of clinical applicability of the previously reported associations between genetic factors and stroke. This review is an update and an extensive analysis of the more recent association studies conducted in stroke. We evaluated a number of studies on several candidate genes (including F5, F2, FGA/FGB/FGG, F7, F13A1, vWF, F12, SERPINE1, ITGB3/PLA1/PLA2/ITGA2B, ITGA2, GP1BA, ACE, AGT, NOS3, APOE, LPL, PON1, PDE4D, ALOX5AP, MTHFR, MTR, and CBS), providing a final panel of genes and molecular variants. We categorized this panel in relation to the degree of association with stroke, supported by the results of meta-analyses and case-control studies. Our findings could represent a useful tool to address further molecular investigations and to realize more detailed meta-analyses.

Endothelial Nitric Oxide Synthase Glu298Asp Gene Polymorphism in Periodontal Diseases

BACKGROUND

Endothelial nitric oxide synthase (eNOS) is involved in key steps of immune response. The aim of the present study was to evaluate genotype distribution and genotype-phenotype association in periodontal disease regarding Glu298Asp polymorphism of the eNOS gene.

METHODS

A total of 272 subjects were included into the study. Genomic DNA was obtained from the peripheral blood of 51 chronic periodontitis (CP) patients, 48 generalized aggressive periodontitis (GAgP), and 173 reference controls. Polymerase chain reaction (PCR) amplification and subsequent BanII restriction fragment length polymorphism (RFLP) analysis were used to detect eNOS Glu298Asp polymorphism. Probing depth, clinical attachment loss, plaque accumulation, and bleeding on probing (BOP) were recorded. The data were analyzed by the chi2 test, logistic regression, and Mann-Whitney U test.

RESULTS

The distributions of eNOS Glu298Asp genotypes and alleles were similar among study groups. Subjects with the Asp allele (Asp+) were statistically higher in the CP group compared to the control group (odds ratio [OR] = 1.957; 95% confidence interval [95% CI] = 1.038 to 3.689). In the GAgP group, BOP (%) was significantly higher in patients with the 298Asp allele (Asp+) compared to patients without the Asp allele (Asp-) (P = 0.015).

CONCLUSIONS

The present study showed that eNOS Glu298Asp polymorphism is associated with BOP in GAgP patients. Moreover, the 298Asp allele of the eNOS gene might be related to CP in the Turkish population.

Is there a genetic basis for pediatric stroke?

PURPOSE OF REVIEW Childhood: stroke is more common than brain tumor, but because there is a wide spectrum in terms of etiology and most centers see only a few cases every year, there have been few large studies of genetic and environmental risk factors until recently. This review focuses on the clinical and radiologic methodology required to distinguish phenotypes in patients, and it focuses on the available data on genetic predisposition.

RECENT FINDINGS

A number of conditions with Mendelian inheritance (eg, sickle cell disease) predispose to childhood stroke, but the search for epistatic polymorphisms that explain why some but not all of these patients are affected has been hampered by our poor understanding of the pathophysiology. Emergency vascular imaging, including arteriography and venography, will almost certainly assist with the description of stroke subtypes with different genetic predisposition in these patients and in the important group of children who were completely healthy before their stroke. Environmental exposure (eg, to infection, hypoxemia, and vitamins) may play a crucial role in modifying genetic expression and must be described carefully in prospective studies.

SUMMARY

Now that much of the work on classifying stroke subtypes in children has been undertaken, international collaboration is likely to lead to identification of the genetic and environmental risk factors, and thus to primary and secondary prevention.

Therapeutic implications of human endothelial nitric oxide synthase gene polymorphism

Vascular endothelial dysfunction is now recognized as a common phenomenon in an array of cardiovascular disorders. Production of nitric oxide via the endothelial isoform of nitric oxide synthase [eNOS (previously termed NOS3 or ecNOS)] is vital for a healthy endothelium; several polymorphic variations of the gene encoding eNOS (NOS3) are now known and have been investigated with respect to disease risk. Surprisingly, only approximately half of these studies have demonstrated significant associations between NOS3 polymorphisms and cardiovascular disease, and many reports are contradictory. Central issues include adequate statistical power, appropriateness of control cohorts, multigene interactions and plausible biological consequences. So far, the inconsistencies are not unique to the NOS3 polymorphisms, but probably represent the broad challenges in defining genetic aspects of complex disease processes.