Aging affects the association between endothelial nitric oxide synthase gene polymorphism and acute myocardial infarction in the Korean male population

The contribution of NOS3 variants to coronary artery disease: A combined genetic epidemiology and computational biochemistry perspective

Cardiovascular diseases, particularly coronary artery disease (CAD) and myocardial infarction, are the leading cause of death among people worldwide. CAD is exceedingly complex in its interplay of environment and genetics, with numerous genetic loci contributing to its heritability. Here, we aim at looking into the effects of the NOS3 c.894G>T and 27-bp VNTR polymorphisms on susceptibility to CAD in a population of Turkish Cypriots, at seeing whether these effects correlate with plasma lipid levels and at predicting the functional consequences of each polymorphism tested. A total of 50 subjects with CAD and 100 otherwise healthy subjects were included in the present case-control study. Genomic DNA was extracted from peripheral blood samples, and the two NOS3 polymorphisms were determined by restriction endonuclease analysis of PCR amplicons. Complementary methods of statistical analysis and computational modeling were employed accordingly to achieve the aims above. Our findings show that the 27-bp VNTR polymorphic locus, but not the c.894G>T polymorphic locus, is associated with CAD and that it may regulate NOS3 pre-mRNA splicing in a length-dependent manner. Overall, along with additional, yet-to-be ascertained susceptibility markers the 27-bp VNTR 4a/4b marker may be employed in risk stratification in community-level screening for CAD among Turkish Cypriots.

Genetic factors associated with endothelial dysfunction affect the early onset of coronary artery disease in Korean males

The maintenance of balance between nitric oxide (NO) and the superoxide anion is required for proper functioning of the endothelium. To investigate the relationship between genetic factors associated with endothelial function and the development of coronary artery disease (CAD), endothelial nitric oxide synthase ( ecNOS) gene a/b polymorphism and NADH/NADPH oxidase p22 phox gene C242T polymorphism were examined in 305 Korean male CAD patients and 215 healthy male control subjects. The β-fibrinogen gene H1/H2 polymorphism was also analyzed. Both ecNOS a/b and p22 phox C242T polymorphisms were found to be associated with the development of CAD in the study population ( p = 0.020 and 0.011, respectively). When the association was analyzed by age, statistical significance was retained only in those <51 years ( p = 0.021 and 0.025 for the a/b and the C242T polymorphism, respectively) and not in those >51 years of age ( p =0.155 and 0.278 respectively). However, the distribution of the β-fibrinogen H1/H2 genotypes was not found to be associated with the development of CAD in either the ≤50 ( p = 0.611) or >50 groups ( p = 0.188). The ecNOS gene a/b polymorphism and the NADH/NADPH oxidase p22 phox gene C242T polymorphism were found to be significantly associated with the development of CAD in Korean male patients less than 51 years old.

Association of endothelial nitric oxide synthase gene polymorphisms with coronary artery disease: an updated meta-analysis and systematic review

Several association studies of endothelial nitric oxide synthase (NOS3) gene polymorphisms with respect to coronary artery disease (CAD) have been published in the past two decades. However, their association with the disease, especially among different ethnic subgroups, still remains controversial. This prompted us to conduct a systematic review and an updated structured meta-analysis, which is the largest so far (89 articles, 132 separate studies, and a sample size of 69,235), examining association of three polymorphic forms of the NOS3 gene (i.e. Glu298Asp, T786-C and 27bp VNTR b/a) with CAD. In a subgroup analysis, we tested their association separately among published studies originating predominantly from European, Middle Eastern, Asian, Asian-Indian and African ancestries. The pooled analysis confirmed the association of all the three selected SNP with CAD in three different genetic models transcending all ancestries worldwide. The Glu298Asp polymorphism showed strongest association (OR range = 1.28–1.52, and P<0.00001 for all comparisons), followed by T786-C (OR range = 1.34–1.42, and P<0.00001 for all comparisons) and 4b/a, (OR range = 1.19–1.41, and P≤0.002 for all comparisons) in our pooled analysis. Subgroup analysis revealed that Glu298Asp (OR range = 1.54–1.87, and P<0.004 for all comparisons) and 4b/a (OR range = 1.71–3.02, and P<0.00001 for all comparisons) have highest degree of association amongst the Middle Easterners. On the other hand, T786-C and its minor allele seem to carry a highest risk for CAD among subjects of Asian ancestry (OR range = 1.61–1.90, and P≤0.01 for all comparisons).

Endothelial nitric oxide synthase (eNOS) 4b/a gene polymorphisms and coronary artery disease: evidence from a meta-analysis

A variety of studies have suggested that the 4b/a polymorphism in the endothelial nitric oxide synthase (eNOS) was associated with coronary artery disease (CAD) risk. However, the data remain conflicting. The aim of the present meta-analysis was to estimate the overall association between risk of CAD and eNOS 4b/a polymorphism. Case-control, cohort or cross-sectional studies evaluating the association between eNOS 4b/a polymorphism and CAD susceptibility were systematically identified in PubMed up to 31 October 2013. Pooled odds ratios (OR) and corresponding 95% confidence intervals (CIs) were calculated to assess the association in overall and subgroup analyses. A total of 10,617 cases and 8302 controls from 37 studies were included in the study. The results of overall analysis revealed significant positive associations between CAD risk and eNOS 4b/a polymorphism in homozygote comparisons (OR = 1.47, 95% CI = 1.16–1.87), heterozygote comparisons (OR = 1.14, 95% CI = 1.02–1.27) and dominant models (OR = 1.18, 95% CI = 1.06–1.33). In subgroup analyses, similar associations were identified in African individuals, as determined using population-based source subgroups and noted in small-and-moderate sample size subgroups (case sample size or control sample size <500). The current meta-analysis revealed that eNOS 4b/a polymorphisms could be a risk factor for developing CAD, particularly in African populations and population-based subgroups.

Correlation and Identification of Variable number of Tandem repeats of eNOS Gene in Coronary artery disease (CAD)

Endothelium-derived nitric oxide (NO) is synthesized from l-arginine by endothelial nitric oxide synthase (eNOS) encoded by the NOS3 gene on chromosome7. Since reduced NO synthesis has been implicated in the development of coronary atherosclerosis; polymorphisms of NOS gene might be associated with increased susceptibility to coronary artery disease (CAD). We therefore undertook this study to determine the association between the occurrence of CAD and eNOS4 b/a polymorphism in South Indian patients. We investigated the polymorphisms in the 27 base-pair tandem repeats in intron4 of the eNOS gene in 100 unrelated CAD patients with positive coronary angiograms and 100 age and sex matched control subjects without any history of symptomatic CAD. The eNOS gene intron4 b/a VNTR polymorphism was analyzed by polymerase chain reaction. The plasma lipids levels and other risk factors were also determined. The genotype frequencies for eNOS4b/b, eNOS4a/b and eNOS4a/a were 63, 26 and 11 per cent in CAD subjects, and 72, 20 and 8 per cent in control subjects, respectively. The genotype frequencies did not differ significantly between the two groups. The frequency of the a allele was 0.24 per cent in CAD subjects and 0.18 per cent in control subjects and no significant association was found between patients and control group (P = 0.57, Odds ratio = 3.62). Plasma lipids, glucose and creatinine levels were significantly increased in CAD group. The genotypic frequencies and the allele frequency did not differ significantly between the CAD patients and controls indicating that this polymorphism was not an independent risk factor for the development of CAD in South Indian patients.

Influence of endothelial nitric oxide synthase gene polymorphisms (−786T>C, 4a4b, 894G>T) in Korean patients with coronary artery disease

INTRODUCTION

Endothelium-derived nitric oxide (NO) is synthesized from l-arginine by endothelial nitric oxide synthase (eNOS) encoded by the eNOS3 gene on chromosome 7. The effects of the eNOS polymorphisms with the risk of coronary artery disease are conflicting. In this study, we investigated the association of the eNOS genotypes with coronary artery disease in Koreans.

MATERIALS AND METHODS

A case-control study was performed to evaluate the association between the eNOS -786T>C, 4a4b, or 894G>T polymorphism and coronary artery disease. 147 consecutive patients with coronary artery disease and 222 healthy controls were recruited. The genotypes of eNOS -786T>C and 894G>T polymorphisms were determined by the polymerase chain reaction-restriction fragment length polymorphism analysis. The genotypes of a 27 bp insertion/deletion in intron 4 (eNOS 4a4b) were determined by the banding pattern on gel electrophoresis.

RESULTS

The eNOS -786T>C (odds ratio [OR]; 1.61, 95% confidence interval [CI]; 0.97-2.69), 894G>T (OR; 1.12, 95% CI; 0.65-1.92) and 4a4b (OR; 1.44, 95% CI; 0.87-2.39) polymorphisms were not an independent predisposition factor to coronary artery disease. However, a subgroup analysis adjusted with various cardiovascular risk factors confirmed positive association of the -786T>C polymorphism in CAD patients with hypertension and a smoking history and also a significant association of the intron 4 genotypes with a smoking history, but no significance has been found in the eNOS polymorphisms of 894G>T upon any risk adjustment. In this study we also found that the distribution of heterozygotes (-786TC, 894GT, and 4a4b) and variant homozygotes for the -786C, 894T, and intron 4a alleles of eNOS in Koreans were significantly lower than in Caucasian populations.

CONCLUSIONS

The present study demonstrates that polymorphisms of the eNOS -786T>C and 4a4b are associated with coronary artery disease with adjustments for cardiovascular risk factors in the Koreans.

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.

Interaction between -786TC polymorphism in the endothelial nitric oxide synthase gene and smoking for myocardial infarction in Korean population

BACKGROUND

Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) mediates endothelium-dependent vasodilation and antithrombotic action. Controversial results regarding the association of eNOS gene polymorphisms with myocardial infarction (MI) have been reported.

METHODS

A total of 932 individuals living in Seoul and the suburb, Korea, were randomly selected. Genomic DNA was prepared from blood leukocytes. A GT missense mutation in exon 7 (894GT) was screened using PCR-RFLP analysis. The genotypes of 3 mutations (-786TC, -922AG, and -1468TA) in the 5'-flanking region were determined by a minisequencing protocol (SNaPshot), respectively.

RESULTS

Pair-wise linkage analysis revealed that 3 mutations of -786TC, -922AG, and -1468TA were completely linked with each other (mid R:D'mid R:=1, r(2)=0.96-1.0). Furthermore, each of these mutant alleles (-786C, -922G, or -1468A), but not 894T allele, was associated with the risk of MI. Multiple logistic regression analysis revealed that each of these mutant alleles was a predictive independent risk factor for the risk of MI (odds ratio, 1.69 for dominant effects, P<0.05) after age and sex adjustments. Smoking further increased the odds ratio by 2.04 for the risk of MI when it was combined with the mutant alleles.

CONCLUSION

Each of 3 mutations (-786TC, -922AG, or -1468TA) in the 5'-flanking region of eNOS gene may play a role in the pathogenesis of MI in Korean population, and also provides an evidence for a significant interaction between these mutations and smoking.

Single nucleotide polymorphisms: aging and diseases

Differences of more than 3 million nucleotides can bee seen comparing the genomes of two individuals as a result of single nucleotide polymorphism (SNP). More and more SNPs can be identified and it seems that these alterations are behind of several biological phenomena. Personal differences in these nucleotides result for example in elevated disease susceptibilities, that is, certain nucleotides are more frequent in patients suffering from different diseases comparing to the healthy population. SNPs may cause substantial alterations in the cells, e.g. the enzyme activity of the respective gene changes, but in other cases the effects of the SNPs are not so pronounced. Later results indicate that SNPs can be rendered to individuals living a longer life than the average. Perhaps these results will not directly lead to the lengthening of the maximal life span; however, genes that play an important role in the aging process could be identified. In this respect SNPs are important factors in determining the information level of the cells of individuals which determines the maximal life span (I. Semsei On the nature of aging. Mech. Ageing Dev . 2000; 117: 93-108), in turn SNP is one of the factors that determine the aging process. Since there are certain age-related diseases, the discovery and the description of the SNPs as a function of age and diseases may result in a better understanding of the common roots of aging and those diseases.

Endothelial Nitric Oxide Synthase Genotype and Ischemic Heart Disease

Background— Polymorphisms in the endothelial nitric oxide synthase (eNOS) gene may influence the risk of ischemic heart disease (IHD), but data from published studies with individually low statistical power are conflicting. To evaluate the role of polymorphisms in the eNOS gene in IHD, we considered all available studies in a meta-analysis.

Methods and Results— Case-control studies evaluating the association between the Glu298Asp, −786T>C, and intron-4 polymorphisms and IHD were searched in MEDLINE and EMBASE up to January 2003. The principal prior hypothesis was that homozygosity for eNOS Asp298, the −786C allele in the promoter, or the intron-4 ( a allele) would be associated with an increased risk of IHD. Data were available for 9867 cases and 13 161 controls from 26 studies. Homozygosity for the Asp298 was associated with an increased risk of IHD (OR, 1.31; 95% CI, 1.13 to 1.51). Although there was significant heterogeneity among studies of Asp298 ( P Het =0.0002), which was largely accounted for by a single study, the increase in risk was still significant after exclusion of that study from analysis. Homozygosity for the intron-4 a allele was also significantly associated with higher risk of IHD (OR, 1.34; 95% CI, 1.03 to 1.75). However, no significant association was found with the −786C allele (OR, 1.06; 95% CI, 0.89, 1.25).

Conclusions— Individuals homozygous for the Asp298 and intron-4 a alleles of eNOS are at moderately increased risk of IHD. These findings support the proposal that common genetic variations in the eNOS gene contribute to atherosclerosis susceptibility, presumably by effects on endothelial NO availability.

Association of a polymorphism of the ecNOS gene with myocardial infarction in a subgroup of Turkish MI patients

In this study we examined a possible association between a 27 base pair (bp)-repeat polymorphism in intron 4 of the ecNOS gene and myocardial infarction (MI) in a subgroup of the Turkish population. We compared MI and control groups for the frequencies of the ecNOS alleles and their genotypes. The frequency of the ecNOS 4a/a and 4a/b genotypes was found to be significantly higher in the MI group than in the control group. Interestingly, the frequency of the ecNOS 4a/b polymorphism was found to be significantly higher in the selected MI group (patients with no known secondary risk factors) than in the control and non-selected MI group. We found that the patients with MI had the frequency of the a/a genotype 4.3%, of the a/b genotype 26.6% and the b/b genotype 69.1%. The controls, however, showed only 0.6% for a/a, 18.0% for a/b and 81.4% for the b/b genotype (P < 0.001; chi2 = 13.626). In this study, we show that myocardial infarction is associated with one subtype of ecNOS gene polymorphism.

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.

Gene polymorphisms of endothelial nitric oxide synthase and angiotensin-converting enzyme in patients with asthma

BACKGROUND

Nitric oxide, including that produced by endothelial constitutive nitric oxide synthase (ecNOS), may regulate vascular and airway tone in the lungs and may influence various aspects of airway homeostasis. Angiotensin-converting enzyme (ACE) is expressed at high levels in the lungs and plays a role in the metabolism of angiotensin II, bradykinin, and substance P, all of which are potentially involved in the pathogenesis of asthma. An insertion-deletion polymorphism of the ACE gene has been shown to be associated with enzyme activity levels of ACE. To examine the possible involvement of the ecNOS and/or ACE genes as the genetic basis of bronchial asthma, we investigated whether there was any association between bronchial asthma and polymorphisms of the ecNOS and/or ACE genes.

METHODS

A total of 310 patients with bronchial asthma and 121 healthy subjects took part in this study. The ecNOS and ACE genotypes were determined in all subjects by polymerase chain reaction.

RESULTS

1) The distribution of one genotype (bb) of ecNOS was significantly higher in the asthma group than in the control population. 2) The ACE genotype distribution was not significantly different between the control and the asthma groups. 3) In asthmatic patients, the ACE and ecNOS genotype distribution did not differ significantly among groups of patients with different severities of asthma.

CONCLUSIONS

These results suggest that polymorphisms of the ecNOS gene, but not the ACE gene, may be associated with the development of asthma. However, the severity of asthma may not be influenced by polymorphisms of the ecNOS and ACE genes.

Endothelial nitric oxide synthase gene sequence variations and vascular disease

Genes contribute significantly to interpopulation differences in vascular disease. Endothelial nitric oxide synthase (eNOS)-a key regulator of vascular nitric oxide production-has been investigated extensively to determine the relevance of DNA variants in the eNOS gene and vascular diseases. Variants in the promoter region, introns, and exons have been explored in a large number of populations but findings have been inconsistent. This paper reviews the current status of functional significance for reported sequence variations in the eNOS gene and the relevance of these variants to different forms of vascular diseases.