Association analysis of endothelial nitric oxide synthase gene polymorphism with primary hypertension in a Singapore population

Polymorphisms in the Renin-Angiotensin System and eNOS Glu298Asp Genes Are Associated with Increased Risk for Essential Hypertension in a Mexican Population

Background

Essential hypertension is the result of modifiable and genetic factors, and it is associated with increased risk for atherothrombosis. Some polymorphisms are associated with hypertensive disease. The objective was to analyze the association between eNOS Glu298Asp, MTHR C677T, AGT M235T, AGT T174M, and A1166C and ACE I/D polymorphisms with essential hypertension in the Mexican population.

Materials and Methods

In the present study, 224 patients with essential hypertension and 208 subjects without hypertension were included. The Glu298Asp, C677T, M235T, T174M, A1166C, and I/D polymorphisms were determined by the PCR-RFLP technique.

Results

We found statistical differences in age, gender, BMI, systolic and diastolic blood pressure, and total cholesterol between control and cases. However, we found no significant differences in HbA1c and triglycerides between both groups. We observed statistical significant differences in the genotype distribution of Glu298Asp (P = 0.001), I/D (P = 0.02), and M235T (P = 0.004) polymorphisms between both groups. In contrast, there were no differences related to distribution of genotypes of MTHFR C677T (P = 0.12), M174T (P = 0.46), and A1166C (P = 0.85) between cases and control groups.

Conclusions

We identified that Glu298Asp, I/D, and M234T polymorphisms represented an increased risk for essential hypertension and those genetic variants could contribute to the presence of endothelial dysfunction and vasopressor effect, hyperplasia, and hypertrophy of smooth muscle cells, which had an impact for hypertension. In contrast, we found no association between C677C, M174T, and A1166C polymorphisms and hypertensive disease. We suggested that those genetic variants could be identified in individuals with high risk to avoid hypertension and thrombotic disease.

A meta-analysis for association of eNOS VNTR 4b/a, - 786 T > C and + 894G > T polymorphisms with risk of recurrent pregnancy loss

BACKGROUND

The association of polymorphisms at nitric oxide synthases (eNOS) gene with recurrent pregnancy loss (RPL) susceptibility has been the focus of attention in several studies. However, the conclusions have been divergent and controversial. Therefore, we performed this study to precisely evaluate the association of eNOS polymorphisms with the risk of RPL.

METHODS

A universal search in PubMed, Web of Knowledge, SciELO, MedRxiv, Scopus and web of Science was performed to identify relevant studies up to January 25, 2020.

RESULTS

A total of 39 eligible studies including 15 studies with 2274 cases and 1933 controls on VNTR 4b/a, nine studies with 1640 cases and 1268 controls on -786C > T, and 15 studies with 2660 cases and 2557 controls on + 894G > T polymorphism were selected. Pooled data revealed that eNOS VNTR 4b/a (dominant model: OR = 1.174, 95% CI 1.021-1.350, p = 0.025) and + 894G > T (allele model: OR = 1.278, 95% CI 1.024-1.595, p = 0.030; homozygote model: OR = 1.442, 95% CI 1.084-1.917, p = 0.012; dominant model: OR = 1.305, 95% CI 1.006-1.693, p = 0.045; and recessive model: OR = 1.378, 95% CI 1.045-1.817, p = 0.023) polymorphisms were significantly associated with an increased risk of RPL, but not  - 786 T > C. Stratified analysis by ethnicity revealed that the eNOS + 894G > T was associated with RPL risk in Asians.

CONCLUSIONS

To sum up, our results indicated that the eNOS VNTR 4b/a and + 894G > T polymorphisms might be contributing to RPL development, but not the  - 786C > T polymorphism.

The Role of Single Nucleotide Variants of NOS1, NOS2, and NOS3 Genes in the Development of the Phenotype of Migraine and Arterial Hypertension

Migraine (M) and arterial hypertension (AH) are very common diseases. Today, there are a number of studies confirming and explaining their comorbidity. We searched PubMed, Springer, Scopus, Web of Science, Clinicalkeys, and Google Scholar databases for full-text English publications over the past 15 years using keywords and their combinations. The present review provides a synthesis of information about single nucleotide variants (SNVs) of NOS1, NOS2, and NOS3 genes involved in the development of M and essential AH. The results of 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, as well as different social and geographical environments. Despite a high prevalence of the M and AH phenotype, its genetic markers have not yet been sufficiently studied. Specifically, there are separate molecular genetic studies aimed to identify SNVs of NOS1, NOS2, and NOS3 genes responsible for the development of M and those responsible for the development of AH. However, these SNVs have not been studied in patients with the phenotype of M and AH. In this review, we identify the SNVs that would be the most interesting to study in this aspect. Understanding the role of environmental factors and genetic predictors will contribute to a better diagnostics and exploration of new approaches to pathogenetic and disease-modifying treatment of the M and AH phenotype.

The Role of Single-Nucleotide Variants of NOS1, NOS2, and NOS3 Genes in the Comorbidity of Arterial Hypertension and Tension-Type Headache

Patients with tension-type headache (TTH) have an increased risk of developing arterial hypertension (AH), while hypertensive subjects do seem to have an increased risk of TTH. We searched for full-text English publications in databases using keywords and combined word searches over the past 15 years. In addition, earlier publications of historical interest were included in the review. In our review, we summed up the single nucleotide variants (SNVs) of Nitric Oxide Synthases (NOSs) genes involved in the development of essential AH and TTH. The results of studies we discussed in this review are contradictory. This might be due to different designs of the studies, small sample sizes in some of them, as well as different social and geographical characteristics. However, the contribution of genetic and environmental factors remains understudied. This makes the issue interesting for researchers, as understanding these mechanisms can contribute to a search for new approaches to pathogenetic and disease-modifying treatment of the AH and TTH phenotype. New drugs against AH and TTH can be based on inhibition of nitric oxide (NO) production, blockade of steps in the NO-cGMP pathway, or NO scavenging. Indeed, selective neuronal NOS (n-NOS) and inducible NOS (i-NOS) inhibitors are already in early clinical development.

Endothelial Nitric Oxide Synthase Gene Polymorphisms (- 922A > G, - 786 T > C, Intron 4 b/a VNTR and 894 G > T) and Essential Hypertension: An Association Study with Haplotypes Analysis

Endothelial Nitric Oxide Synthase (eNOS) is an indispensable regulator of blood pressure through producing Nitric Oxide (NO). There is some evidence to suggest that eNOS gene polymorphisms are associated with Essential Hypertension (EHT). In this study, the potential association between eNOS 4a/4b, A922G, G894T, T786C gene polymorphisms and EHT as individual risk factors and as haplotypes are examined in the southern population of Iran (Bandar-Abbas). In this study, 200 EHT patients and 200 normotensive subjects which were matched for age and sex were included. Genotyping was performed by either utilizing Polymerase Chain Reaction (PCR) or PCR followed by Restriction Fragment length Polymorphism (RFLP) method. Our results demonstrated statistically significant associations between T786C, G894T, and 4a/4a and EHT (p < 0.05); however, A922G had no significant association with EHT (p > 0.05). Haplotype analysis also suggested that - 786C/- 922A/4a, - 786C/- 922A/4b and - 786C/- 922G/4a haplotypes were more frequent in EHT group than control group, hypothesizing a positive association with EHT. The present study has identified that the eNOS genetic variations are associated with EHT in southern population of Iran (Bandar-Abbas). These findings also suggested that a number of haplotypes of eNOS gene may be a driving factor for EHT susceptibility in respected population.

The polymorphism G894 T of endothelial nitric oxide synthase (eNOS) gene is associated with susceptibility to essential hypertension (EH) in Morocco

BACKGROUND

Hypertension is a multifactorial disease involving both environmental and genetic Factros. G894 T eNOS polymorphism has been suggested to be responsible for reduced NO synthesis, and EH development. The objective of our case-control study is to evaluate the potential association of G894 T eNOS polymorphism with Essential Hypertension (EH) susceptibility, among a sample of Moroccan patients.

METHODS

One hundred forty five hypertensive patients were recruited from the department of Cardiology, University Hospital Center Ibn Rochd, Casablanca, Morocco, and compared to 184 apparently healthy subjects. DNA samples were genotype by PCR-RFLP method using MboI restriction enzyme.

RESULTS

Our results showed a positive correlation between G894 T eNOS distribution and Alcohol and Obesity rik factors (P = 0.009 and 0.02 respectively). Patients with elevated Cardio Vascular Risk (CVR) carried out the higher frequency of homozygous mutant genotype TT (62.2%) and T mutant allele (77.8%), compared to median and low CVR groups. G894 T eNOS distribution was significantly associated to a high risk of EH occurrence under the GT and TT genotypes (OR [95% CI] = 20.2 [7.7-52.4], P <  0.0001; OR [95% CI] = 332.5 [98.2-1125.4], P <  0.0001 respectively), and the 3 genotypic transmission models (Dominant: OR [95% CI] = 43.2 [17.9-104.09], P <  0.0001; Recessive: OR [95% CI] = 47.7 [18.6-122.3]; P <  0.0001; Additive: OR [95% CI] = 14.02 [9.6-20.45], P <  0.0001).

CONCLUSION

Our study suggests a strong association of G894 T eNOS polymorphism with susceptibility to EH in Morocco. Studies trying to identify contributing genes may be very useful and allow recognizing the vulnerable individuals and classifying patients in subgroups with definite genetic and pathogenic mechanisms to achieve better prevention and therapeutics.

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.

Effect of eNOS polymorphisms on salbutamol evoked endothelium dependent vasodilation in South Indian healthy subjects

BACKGROUND

The model of pulse plethysmograph using inhalational salbutamol 400 mcg is studied well to assess endothelium dependent vasodilation. Endothelial nitric oxide synthase (eNOS) gene polymorphism may influence the response to salbutamol in healthy subjects.

AIM

To find the effect of polymorphisms 894G>T and -786T>C of eNOS gene on endothelium dependent vasodilation in healthy subjects.

MATERIALS AND METHODS

One hundred and two south Indian healthy subjects of either sex, aged between 18 to 35 years were recruited for the study. The digital volume pulse (DVP)was measured by pulse plethysmograph before and after salbutamol 400mcg inhalation. Three predose and five postdose recordings of DVP were measured. The average change in the DVP parameters namely reflection index (RI) and stiffness index (SI) were determined. The eNOS894G>T and -786T>C gene polymorphism were genotyped using polymerase chain reaction followed by restriction fragment length polymorphism. The percentage changes in RI and SI from predose baseline recordings were calculated and compared between the genotype groups.

RESULTS

The genotype and allele frequency of study subjects were in Hardy-Weinberg equilibrium. The changes in DVP parameters were not significantly different between the genotype groups.

CONCLUSION

eNOS polymorphism do not affect salbutamol evoked endothelium dependent vasodilation in the model of pulse plethysmograph in healthy subjects.

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.

Variants of endothelial nitric oxide synthase gene are associated with components of metabolic syndrome in an Arab population

Genetics plays a crucial role in the development of metabolic syndrome (MetS). Here we examined the association between endothelial nitric oxide synthase (eNOS) gene polymorphisms and MetS in a Saudi Arabian cohort to extend the understanding of the genetic basis of MetS in diverse ethnic populations. Anthropometric, clinical and biochemical parameters as well as genotyping for 894G>T, -786T>C variants of eNOS gene by PCR-RFLP and 4a/b by direct PCR were performed in 886 Saudi Arabians (477 MetS and 409 Non-MetS). The genotype distribution (TT, p=0.001; TC, p=0.001; TC+CC, p=0.001) and allele (T, p=0.007; C, p=0.007) frequency of the -786T>C SNP were significantly different between Non-MetS and MetS subjects which remained significant after Bonferroni correction. Moreover: 1) the GT and GT+TT genotypes of the 894G>T SNP were associated with elevated blood pressure (p=0.017, and p=0.022, respectively); 2) the ab variant of 4a/b polymorphism was associated with decreased HDL levels (p= 0.044); and 3) the TC+CC genotype and C allele of the -786T>C SNP were associated with increased fasting glucose levels (p=0.039, and p=0.028, respectively). Also, G-a-C was identified as the risk haplotype for MetS susceptibility (p=0.034). The results suggest a significant association of 894G>T, 4a/b and -786T>C polymorphisms with MetS and its components is present in an Arab population. A genetic predisposition to develop abnormal metabolic phenotypes, consistent with an increased prevalence of metabolic phenotypes can be detected in this ethnic group.

The 27-bp VNTR polymorphism in intron 4 of the human eNOS gene in healthy Singaporean Chinese, Indians, and Malays

Human endothelial nitric oxide synthase (eNOS) is one isoform of the nitric oxide synthases that are responsible for nitric oxide synthesis from L-arginine. The gene encoding eNOS contains a 27-bp VNTR polymorphism in intron 4. We report here for the first time the presence of a novel allele 3, which was absent in all other populations studied to date, in 1.7% each of Singaporean Indians and Malays. We also detected the presence of a novel genotype 3/5 in 3.4% each of Singaporean Indians and Malays. Allele 6, which was absent in Han Chinese from northern China and Taiwan and was also absent in Indians from the Indian subcontinent, was found in 2.1% of Singaporean Chinese and in 0.3% of Singaporean Indians.

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

Background

Numerous individually underpowered association studies have been conducted on endothelial nitric oxide synthase (eNOS) genetic variants across different ethnic populations, however, the results are often irreproducible. We therefore aimed to meta-analyze three eNOS widely-evaluated polymorphisms, G894T (rs1799983) in exon 7, 4b/a in intron 4, and T−786C (rs2070744) in promoter region, in association with hypertension from both English and Chinese publications, while addressing between-study heterogeneity and publication bias.

Methods

Data were analyzed using Stata software (version 11.0), and random-effects model was applied irrespective of between-study heterogeneity, which was evaluated by subgroup and meta-regression analyses. Publication bias was weighed using the Egger's test and funnel plot.

Results

There were total 19284/26003 cases/controls for G894T, and 6890/6858 for 4b/a, and 5346/6392 for T−786C polymorphism. Overall comparison of allele 894T with 894G in all study populations yielded a 16% increased risk for hypertension (odds ratio [OR] = 1.16; 95% confidence interval [95% CI]: 1.07–1.27; P = 0.001), and particularly a 32% increased risk (95% CI: 1.16–1.52; P<0.0005) in Asians and a 40% increased risk (95% CI: 1.19–1.65; P<0.0005) in Chinese. Further subgroup analyses suggested that published languages accounted for the heterogeneity for G894T polymorphism. The overall OR of allele 4a versus 4b was 1.29 (95% CI: 1.13–1.46; P<0.0005) in all study populations, and this estimate was potentiated in Asians (OR = 1.42; 95% CI: 1.16–1.72; P<0.0005). For T−786C, ethnicity-stratified analyses suggested a significantly increased risk for −786C allele (OR = 1.25; 95% CI: 1.06–1.47; P = 0.007) and −786CC genotype (OR = 1.69; 95% CI: 1.20–2.38; P = 0.003) in Whites. As an aside, the aforementioned risk estimates reached significance after Bonferroni correction. Finally, meta-regression analysis on other study-level covariates failed to provide any significance for all polymorphisms.

Conclusion

We, via a comprehensive meta-analysis, ascertained the role of eNOS G894T and 4b/a polymorphisms on hypertension in Asians, and T−786C polymorphism in Whites.

Association between CYP3A5 polymorphisms and blood pressure in kidney transplant recipients receiving calcineurin inhibitors

Abstract Renal cytochrome P450 3A5 (CYP3A5) has been associated with blood pressure (BP) control in humans. We investigated whether CYP3A5 polymorphisms are associated with post- transplant hypertension in a selected population of kidney recipients receiving calcineurin inhibitors. Ninety-two kidney transplant recipients receiving cyclosporine (CyA) or tacrolimus (Tac) were genotyped for CYP3A5 polymorphisms, and the association between the CYP3A5 alleles (*1,*3) and hypertension on post-operative day (POD) 6 and POD 180 was verified, with multiple regression being used to identify the putative co-variates that may predict the extent and severity of hypertension in transplant recipients at different post-transplant times. The CYP3A5*1 carriers had higher systolic (SBP) and diastolic blood pressure (DBP) in both the immediate and delayed post-transplant period when adjusted for anti-hypertensive medication (POD 6: SBP = 161 ± 23 vs. 140 ± 23 mmHg; DBP = 120 ± 15 vs. 87 ± 14 mmHg, p < 0.05. POD 180: SBP = 136 ± 16 vs. 129 ± 14 mmHg; DBP = 89 ± 15 vs. 80 ± 15 mmHg, p < 0.05). The severity of hypertension between the CYP3A5*1 carriers and noncarriers on POD 6 was documented by the significantly different distribution of hypertension classes, but this was not confirmed on POD 180. The CYP3A5 genotype was the only independent variable affecting mean arterial pressure. The results of this study show that CYP3A5 polymorphisms are associated with the severity and degree of hypertension in kidney transplant recipients receiving calcineurin inhibitors regardless of the time of recording. However, the role of concomitant medications such as steroids with strong CYP3A5 inducing activity, should be taken into account.

Genetics of salt-sensitive hypertension

The assessment of salt sensitivity of blood pressure is difficult because of the lack of universal consensus on definition. Regardless of the variability in the definition of salt sensitivity, increased salt intake, independent of the actual level of blood pressure, is also a risk factor for cardiovascular morbidity and mortality and kidney disease. A modest reduction in salt intake results in an immediate decrease in blood pressure, with long-term beneficial consequences. However, some have suggested that dietary sodium restriction may not be beneficial to everyone. Thus, there is a need to distinguish salt-sensitive from salt-resistant individuals, but it has been difficult to do so with phenotypic studies. Therefore, there is a need to determine the genes that are involved in salt sensitivity. This review focuses on genes associated with salt sensitivity, with emphasis on the variants associated with salt sensitivity in humans that are not due to monogenic causes. Special emphasis is given to gene variants associated with salt sensitivity whose protein products interfere with cell function and increase blood pressure in transgenic mice.

Understanding the genetic basis for adverse drug effects: the calcineurin inhibitors

The calcineurin inhibitors-cyclosporine and tacrolimus-are the mainstay of immunosuppressive therapy in solid organ transplantation. These drugs produce severe adverse drug effects (ADEs) such as nephrotoxicity, posttransplantation diabetes mellitus, and hypertension. Accumulated evidence suggests that the development of type 2 diabetes, hypertension, and renal failure may be associated with specific DNA genotypes. In this review, the genes involved with the development of these disease processes are compared with those implicated in calcineurin inhibitor-induced ADEs. The renin-angiotensin system genes, cytokine-encoding genes, and plasminogen activator inhibitor type 1 genes have been implicated in calcineurin inhibitor-induced nephrotoxicity, as well as in development of renal failure. A number of genes are implicated in contributing to diabetes, and these include the vitamin D receptor gene, VDR; hepatocyte nuclear factor genes, HNF; transcription factor 7-like 2 gene, TCF7L2; angiotensin-converting enzyme gene, ACE; cytokines; peroxisome proliferator-activated receptor gamma gene, PPARG; and others. Studies have suggested that the VDR, PPARG, HNF1A, and adenosine 5'-triphosphate-binding cassette ABCC8 (which encodes the sulfonylurea receptor) genes are associated with calcineurin inhibitor-induced diabetes. The genes encoding for the angiotensin-converting enzyme, endothelial constitutive nitric oxide synthase, and cytochrome P450 3A isoenzyme have been involved in the development of hypertension and in calcineurin inhibitor-induced hypertension. The genetic study of disease states can be the stepping stones for thoroughly understanding the genetic basis of ADEs. Gene polymorphisms are implicated in the development of diseases and corresponding disease-like ADEs. The disease-associated genes provide candidate genes for exploring ADEs and may provide genomic biomarkers for assessing the risk for developing severe calcineurin inhibitor-related ADEs as well as for developing preventive strategies.

Association of NOS3 Glu298Asp SNP with hypertension and possible effect modification of dietary fat intake in the ARIC study

Endothelial nitric oxide synthase breaks down nitric oxide and has a key role in blood pressure regulation. Earlier studies have shown associations between single nucleotide polymorphisms (SNPs) in the NOS3 gene and hypertension. Studies also suggest that such associations may vary by dietary fat intake. We investigated associations between the NOS3 Glu298Asp SNP (rs1799983) and hypertension, as well as the interaction between NOS3 genotypes and dietary fat intake using data from baseline examination in white and African American participants in the Atherosclerosis Risk in Community (ARIC) study. Dietary fat intake was measured by a Food Frequency Questionnaire during the baseline examination in 15 792 individuals aged 45-64 years in ARIC study participants. Race-stratified unconditional logistic regression was performed to investigate the association between prevalent hypertension and NOS3 Glu298Asp genotypes. There was no significant interaction between dietary fat intake and NOS3 Glu298Asp genotype with regards to hypertension status in either African Americans or whites (P for interaction=0.3 and 0.4, respectively). We found a significant relationship between NOS3 Glu298Asp and triglycerides in African Americans. We did not find an association between the NOS3 Glu298Asp polymorphism and hypertension, and dietary fat intake did not interact with NOS3 genotypes to influence hypertension. We recommend further exploration of the relationship between NOS3 Glu298Asp and triglycerides in African Americans.

The association of endothelial nitric oxide synthase G894T polymorphism with C-reactive protein level and metabolic syndrome in a Chinese study group

Some studies have reported a possible relationship between endothelial nitric oxide synthase (eNOS) and metabolic syndrome (MS), which is associated with an increased risk for cardiovascular disease. A recent meta-analysis study found the eNOS G894T polymorphism to be associated with ischemic heart disease. Here, we examine the association of eNOS G894T polymorphism with MS in a Chinese population (n = 397). The eNOS T+ (TT and GT) genotypes (56.92% vs 38.86%; odds ratio, 2.08; 95% confidence interval, 1.21-3.56; P = .007) and T allele (33.08% vs 23.34%; odds ratio, 1.62; 95% confidence interval, 1.08-2.44; P = .019) were significantly more frequent in subjects who had MS. Furthermore, subjects with eNOS T+ genotypes had significantly higher plasma C-reactive protein levels as compared with GG subjects (P = .004). This study shows that, in a Chinese population, eNOS G894T polymorphism is associated with an elevated C-reactive protein level and MS.

Gender specific association of endothelial nitric oxide synthase gene (Glu298Asp) polymorphism with essential hypertension in a south Indian population

BACKGROUND

Endothelial derived nitric oxide (NO) plays a major role in blood pressure regulation. The role of missense variant eNOS-Glu298Asp has been demonstrated by many studies with conflicting results. Our objective was to investigate the association of eNOS gene polymorphism with essential hypertension in a south Indian population.

METHODS

We carried out a case control study in 438 hypertensive patients and 444 healthy control subjects in a homogenous population. Genotyping was done by PCR-RFLP method. Multiple logistic regression analysis was used to detect the association between genotype and hypertension.

RESULTS

The homozygous variant genotype Asp298Asp was significantly associated with hypertension (odds ratio 2.4; 95% CI, 1.23-5.0, p<0.01). Gender specific analysis showed both the heterozygous (odds ratio, 2.0; 95% CI, 1.3-2.9, p<0.01) and homozygous variants (odds ratio, 7.9; 95% CI, 2.0-4.1, p<0.001) were positively associated with hypertension in females. The variant allele Asp was higher in female hypertensives when compared to male hypertensive cases (22% vs. 16%).

CONCLUSION

The eNOS gene polymorphism is a candidate gene for hypertension and the association to be gender specific with respect to females in a south Indian Tamilian population.

Habitual energy expenditure modifies the association between NOS3 gene polymorphisms and blood pressure

BACKGROUND

The endothelial nitric-oxide synthase (NOS3) gene encodes the enzyme (eNOS) that synthesizes the molecule nitric oxide, which facilitates endothelium-dependent vasodilation in response to physical activity. Thus, energy expenditure may modify the association between the genetic variation at NOS3 and blood pressure.

METHODS

To test this hypothesis, we genotyped 11 NOS3 polymorphisms, capturing all common variations, in 726 men and women from the Medical Research Council (MRC) Ely Study (age (mean +/- s.d.): 55 +/- 10 years, body mass index: 26.4 +/- 4.1 kg/m(2)). Habitual/non-resting energy expenditure (NREE) was assessed via individually calibrated heart rate monitoring over 4 days.

RESULTS

The intronic variant, IVS25+15 [G-->A], was significantly associated with blood pressure; GG homozygotes had significantly lower levels of diastolic blood pressure (DBP) (-2.8 mm Hg; P = 0.016) and systolic blood pressure (SBP) (-1.9 mm Hg; P = 0.018) than A-allele carriers. The interaction between NREE and IVS25+15 was also significant for both DBP (P = 0.006) and SBP (P = 0.026), in such a way that the effect of the GG-genotype on blood pressure was stronger in individuals with higher NREE (DBP: -4.9 mm Hg, P = 0.02. SBP: -3.8 mm Hg, P= 0.03 for the third tertile). Similar results were observed when the outcome was dichotomously defined as hypertension.

CONCLUSIONS

In summary, the NOS3 IVS25+15 is directly associated with blood pressure and hypertension in white Europeans. However, the associations are most evident in the individuals with the highest NREE. These results need further replication and have to be ideally tested in a trial before being informative for targeted disease prevention. Eventually, the selection of individuals for lifestyle intervention programs could be guided by knowledge of genotype.

Three endothelial nitric oxide (NOS3) gene polymorphisms in hypertensive and normotensive individuals: meta-analysis of 53 studies reveals evidence of publication bias

BACKGROUND

Studies on the relationship between endothelial nitric oxide (NOS3) gene variants and hypertension have been conflicting. To explore this hypothesis further, we performed a meta-analysis and re-evaluated the relationship between the three most widely studied NOS3 polymorphisms and hypertension status and blood pressure levels.

METHODS

Data on 40,413 subjects from 53 studies were combined in five distinct meta-analyses, and heterogeneity and publication bias were explored.

RESULTS

Heterogeneity was observed in all meta-analyses. By a random-effects model, carriers of the four 27-basepair repeat variable number of tandem repeats in intron 4 were associated with a 28% increase in the risk of hypertension compared with those homozygous for the 5 repeat: odds ratio (OR) 1.28, 95% confidence interval (CI) 1.11-1.47, P=0.001. In Asian individuals, Asp allele carriers displayed a similar association: OR 1.28, 95% CI 1.06-1.54, P=0.01, as well as a 2 mmHg increase in both systolic (P=0.04) and diastolic (P=0.009) blood pressure levels. Furthermore, meta-regression analysis indicated that the effect of the Glu298Asp genotype on the risk of hypertension might be dependent on total cholesterol status. No effect of the T-786C variant on hypertension was detected. There was evidence that such findings might be a result of selectively reporting/publishing positive reports.

CONCLUSION

Our results suggest that current data on the relationship between NOS3 variants and hypertension are subject not only to important heterogeneity but also to publication bias. Future research should preferentially focus on gene-environment interactions as well as haplotype analyses.