The missense Glu298Asp variant of the endothelial nitric oxide synthase gene is strongly associated with placental abruption

We recently identified a missense variant (Glu298Asp) that lies within exon 7 of the endothelial nitric oxide synthase (eNOS) gene, and that is associated with severe preeclampsia (proteinuric hypertension that develops as a consequence of pregnancy). Maternal hypertension is the most consistently identified factor predisposing to placental abruption. Our objective, therefore, was to analyze the association between the Glu298Asp eNOS gene variant and placental abruption. The study participants included 35 patients with histories of placental abruption and 170 control subjects. Screening for the Glu298Asp eNOS gene variant was carried out by analysis of polymerase chain reaction/restriction fragment length polymorphism. The analyses revealed that the frequency of the Glu298Asp variant (Glu298Asp homozygotes and heterozygotes) was significantly (P<0.001) higher in the placental abruption group (n=14; 40%) than in the control group (n=24; 14%). We conclude that the presence of the Glu298Asp eNOS gene variant could be a marker of increased risk of developing placental abruption.     

Positive association of endothelial nitric oxide synthase gene polymorphism with hypertension in northern Japan

Vascular endothelial cells produce nitric oxide (NO), which contributes to the regulation of blood pressure and regional blood flow. Although Endothelial NO synthase (eNOS) gene polymorphisms have been shown to have a positive association with coronary artery disease, the linkage between eNOS gene polymorphisms and hypertension has been controversial. In the present study, therefore, we identified genotypes for Glu298Asp and variable number tandem repeats in intron 4 (4b/a) in 183 hypertensive and 193 normotensive populations. The Glu298Asp variant had a significant association with hypertension (odds ratio, 1.8; 95% confidence interval, 1.1-3.0). The allele frequencies of 298Asp for Glu298 in hypertensive patients were significantly higher than those in normotensive subjects (0.128 vs 0.080, p<0.05). Diastolic and mean arterial blood pressures were significantly higher in hypertensive subjects with the 298Asp allele than those without the variant allele (p<0.05). However, disequilibrium of 4b/a polymorphism was absent between these two groups. These results suggest that the Glu298Asp variant may be a genetic susceptibility factor for hypertension.     

NO Level and Endothelial NO Synthase Gene Polymorphism （Glu298Asp） in the Patients with Coronary Artery Disease from the Turkish Population

A healthy endothelium plays a core role in cardiovascu-lar control [1]. In the endothelial cell, nitric oxide (NO) issynthesized by the endothelial nitric oxide synthase (eNOS)encoded by a 26-exon gene (NOS 3) located on chromo-some 7 [2]. Besides its regulatory functions on vasomotortone and blood flow, endothelial NO is known to inhibitthe platelet activation and modulate migration and growthof the vascular smooth muscle [3]. Indirect evidence sug-gests that alterations of the NO pathwa…     

Endothelial nitric oxide synthase gene polymorphism in the Indian and Mestizo populations of Mexico

Endothelium-derived nitric oxide (NO) is an important factor in vasodilation synthesized by endothelial nitric oxide synthase (eNOS). A polymorphism (894 G to T) in exon 7 of the eNOS gene causes the conversion of Glu to Asp in position 298. The Glu298Asp polymorphism has been extensively associated with cardiovascular disease. We determined the Glu298Asp polymorphism frequency in healthy Mexican Mestizo, Huastec, Mayo, and Mayan populations by the endonuclease restriction method. The four populations analyzed were in Hardy-Weinberg equilibrium. Allele frequencies were similar among Mexican populations but different when compared with Caucasians. However, when compared with allele frequencies in Asian populations, Mestizo and Huastec allele frequencies were significantly different. Genotypically, only the Mestizos presented Asp298 homozygosity. The absence of double mutants in Indian populations resembles that in Asians. With these data, we conclude that the low frequency of the eNOS Glu298Asp polymorphism in Indian and Mestizo populations of Mexico is related to the Asian origin of Amerindian groups.     

Oxidative stress and eNOS (Glu298Asp) gene polymorphism in preeclampsia in Indian population

Oxidative stress causing widespread endothelial dysfunction has been proposed as a key factor involved in the development of preeclampsia (PE). With this background our objective was to study oxidative stress biomarkers like nitric oxide and malondialdehyde (MDA) and to correlate these markers with endothelial nitric oxide synthase (eNOS) (Glu298Asp) gene polymorphism. This cross-sectional study included 300 pregnant women diagnosed with PE and 200 women with normal pregnancy. Plasma NO and MDA levels were analyzed using student's t test and eNOS gene polymorphism was studied by performing polymerase chain reaction amplification and restriction length polymorphism and frequencies were distributed by using χ(2) analysis. The mean plasma levels of NO were significantly lower in study group while MDA levels were significantly higher in study group (P < 0.001). Genotypic and allelic frequency of eNOS gene in both groups was found to be significant (P < 0.05). The intergenotypic variation of NO and MDA levels was found to be significant (P < 0.001). We concluded that the plasma levels of NO are decreased while MDA levels are increased in subjects with PE and that might contribute to the pathophysiology of PE. As observed in this study Glu298Asp eNOS gene polymorphism showed significant association with PE.     

Association of endothelial nitric oxide synthase gene polymorphisms with classical risk factors in development of premature coronary artery disease

Genetic polymorphism of the endothelial nitric oxide synthase (eNOS) affects the pathogenesis of atherosclerosis and associated with premature coronary artery disease (PCAD). We aimed to explore the association between Glu298Asp polymorphism of the eNOS gene and premature CAD in Egyptians, and the possible interaction between this polymorphism and other risk factors. The study population consisted of 116 patients with PCAD, and 119 controls. Glu298Asp polymorphism (rs1799983) of the eNOS gene was analyzed by polymerase chain reaction (PCR). We found that the TT genotype of the eNOS gene increased the risk of PCAD by 2.6. Hypertension, diabetes, smoking, total cholesterol, triglycerides, LDLc, HDLc and TT genotype of the eNOS gene were independent risk factors for the development of PCAD. We conclude that, the TT genotype of Glu298Asp polymorphism of eNOS gene is an independent risk factor of PCAD in Egyptians. The association of smoking, obesity, dyslipidemia and/or metabolic syndrome with the TT genotype increased the risk of the development of PCAD.     

Association of the Glu298Asp polymorphism in the endothelial nitric oxide synthase gene with essential hypertension resistant to conventional therapy

Endothelial nitric oxide synthase (eNOS) produces nitric oxide (NO) which, after diffusing into vascular smooth muscle cells, activates guanylate cyclase leading to vasodilatation. A polymorphism (894G to T) in exon 7 of the eNOS gene causes the conversion of Glu to Asp in position 298. The recently described crystal structure of the heme domain of eNOS protein shows that Glu298 is fully solvent accessible and distant from regions integral to enzyme function. Searching for phenotypic expression of eNOS gene variants, we genotyped a group of patients with essential hypertension (H, n = 119) for the Glu298Asp polymorphism and compared them with age- and sex-matched healthy normals (N, n = 85). To specify phenotypic expression further, the hypertensive patients were subdivided into one group that responded well to regular antihypertensive therapy (CH, n = 45) and one group that was resistant to the therapy (RH, n = 74). Patients with BP higher than 140/90 mmHg when on adequate lifestyle modification and triple-combination therapy (including diuretics) were considered resistant. In RH and H groups, a significantly higher frequency of T alleles (P = 0.022 and P = 0.046, respectively) was found compared to normotonics (N). In well-controlled hypertonics, the same tendency was found, but did not reach statistical significance. The Glu298Asp polymorphism may contribute to the complex pathogenesis of essential hypertension and may be a factor in the resistance of these patients to conventional antihypertensive therapy. The presence of this allele may thus be predictive of the patients' therapeutic response.     

Analysis of endothelial nitric oxide synthase gene polymorphisms with cardiovascular diseases in eastern Taiwan

A few studies have been carried out to address the correlation between the endothelial nitric oxide synthase (eNOS) gene polymorphisms and cardiovascular diseases (CVD) within the Taiwanese population. However, no report has documented the situations in eastern Taiwan, which has different ethnic groups from those in western Taiwan. In this study, we explored the relationship between polymorphic eNOS alleles and CVD in eastern Taiwan. DNA extraction and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis were employed for the detection polymorphism in exon 7 of the eNOS gene. A total of 198 subjects was included. The subjects were 120 patients with CVD such as hypertension, coronary artery disease (CAD), and stroke. Normal subjects (78) served as control. Analysis of the gene polymorphism revealed that the frequency of the eNOS gene variant containing a 27-bp repeat in intron 4 is similar between control subjects (aa:ab:bb = 0%:21.8%:78.2%), and patients with CVD (aa:ab:bb = 3.3%:21.7%:75.0%). The frequency of the Glu298Asp (894G --> T) polymorphism in exon 7 of the eNOS gene was significantly different between control subjects (TT:GT:-GG = 7.7%:29.5%:62.8%) and patients with CVD (TT:GT:GG = 5.0%:74.2%:20.8%). These results suggest that the Glu298Asp polymorphism in exon 7 of the eNOS gene is likely to be a risk factor for CVD in the eastern Taiwanese population.     

Glu298Asp polymorphism of the endothelial nitric oxide synthase gene in Turkish patients with ischemic stroke

The low plasma nitric oxide concentrations and reduced vascular reactivity are considered major proatherogenic mechanisms in cardiovascular diseases. The present study aimed to assess the allelic frequency and the genotypic distribution of the Glu298Asp gene polymorphism at exon 7 of endothelial nitric oxide synthase (eNOS) gene in Turkish ischemic stroke patients compared to appropriate healthy controls, and to correlate the genetic findings with stroke subtypes. The study population included 146 (75 males, 71 females) patients with ischemic stroke which were categorized according to the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) and 133 (34 males, 99 females) healthy subjects. The eNOS polymorphism was identified with a PCR followed by RFLP with the restriction enzyme BanII. Genotypes were defined as GG, GT, and TT according to the presence of the G and T alleles. In this case-control study, we did not find any significant difference in either the genotypic distribution or allelic frequency of Glu298Asp gene polymorphism between the patients and the controls. In addition, there was also no significant difference for the genotype distribution and the allelic frequency among the stroke subtypes. The results suggested the lack of the association between the Glu298Asp gene polymorphism and ischemic stroke or subtypes of ischemic stroke in the Turkish population.     

Genetic association studies of endothelial nitric oxide synthase gene polymorphisms in women with unexplained recurrent pregnancy loss: a systematic and meta-analysis

Recurrent pregnancy loss (RPL) is a multifactorial disorder, both genetic and environmental factors contribute to the development of RPL. Recently, the association between endothelial nitric oxide synthase (eNOS) gene polymorphisms and unexplained recurrent pregnancy loss (URPL) has been reported, and the results were inconsistent. Hence, we performed the meta-analysis to drive a more precise estimation of association between eNOS polymorphisms and URPL. Odds ratio (OR) and its 95 % confidence interval were calculated under co-dominant (AA vs. BB, TT vs. GG) and additive (A vs. B, T vs. G) genetic models. Studies of eNOS intron 4 VNTR and Glu298Asp were separated by ethnicities. 13 studies included 1,769 URPL cases and 1,376 healthy controls on eNOS intron 4 VNTR polymorphism, and 11 studies were involved in Glu298Asp polymorphism with 1,498 URPL cases and 1,123 healthy controls. The integrated results showed that eNOS Glu298Asp polymorphism was associated with URPL [ORs were 1.91 (1.42–2.56), P < 0.001; 1.67 (1.36–2.04), P < 0.001, respectively]. When analyses were separated by ethnic subgroups, the association between eNOS Glu298Asp polymorphism and URPL was only observed in East Asians [OR = 1.88 (1.52–2.33), P < 0.001 under additive model], and there was no association between eNOS intron 4 VNTR polymorphism and URPL in Caucasians and East Asians. The results indicated a significant association between eNOS Glu298Asp polymorphism and URPL in East Asians. No association was observed between eNOS intron 4 VNTR polymorphism and URPL in Caucasians and East Asians.     

Impact of angiotensin-converting enzyme, angiotensinogen, endothelial NO synthase, and bradykinin receptor B2 gene polymorphisms on myocardium in patients with hypertension and in athletes

We investigated the role of gene polymorphisms in angiotensin-converting enzyme (ACE), angiotensinogen, endothelial NO (eNO) synthase, and bradykinin receptor B2 in determining the cardiovascular system structure and function in hypertension and "athletic heart" syndrome. Using a PCR-based method, 114 hypertensive patients and 94 athletes were genotyped for I/D polymorphism of ACE, M235T angiotensinogen (ANG), Glu298 Asp endothelial synthase (eNOS), and type 2 receptor for bradykinin (BDKR2). Echocardiography and a 24 hour blood pressure monitoring being performed. The (+)-allel of BDKR2 gene was associated with the left ventricular hypertrophy and greater wall thickness in athletes and hypertensive subjects. The hypertensive patients, that were homozygous for Glu298 allele of eNOS, demonstrated a lower level of diastolic blood pressure than did those with Glu298 Asp and Asp298 Asp genotypes. At the same time, the ACE and AND gene polymorphisms displayed no association with the cardiac structure and function.     

High-Speed Detection of the G894T Polymorphism in Exon 7 of the eNOS Gene by Real-Time Fluorescence PCR with the Light-Cycler

In endothelial cells nitric oxide (NO) is synthesized by endothelial-nitric oxide synthase (e-NOS), constitutively expressed and encoded by a 26-exon gene, located on chromosome 7q35-36. The prevalence of the T rare variant of the G894T polymorphism in exon 7 of the e-NOS gene (Glu-->Asp amino acid substitution) has been reported to be significantly higher in patients with coronary spasm and coronary artery disease. To date G894T polymorphism detection is performed by PCR-RFLP assay. In order to establish a high-speed genotyping method, we have taken advantage of the Light Cycler instrument, a thermal cycler that combines rapid-cycle DNA amplification with a real-time fluorescence monitoring. This technology is based on hybridization of the adjacent fluorescently labeled probes with PCR products. This methodology is considered more accurate and less time-consuming than conventional PCR-RFLP assay. To validate this technique we genotyped 270 healthy subjects. The results were consistent with those obtained from PCR-RFLP assay.     

Consistent interethnic differences in the distribution of clinically relevant endothelial nitric oxide synthase genetic polymorphisms.

A maldistribution of endothelial nitric oxide synthase (eNOS) genetic variants may explain differences in NO-mediated effects and response to drugs among black and white subjects. While interethnic differences in the distribution of eNOS genetic variants exist in the American population, it is not known whether such interethnic differences exist in other populations. To test this possibility, we examined the distribution of genetic variants of three clinically relevant eNOS polymorphisms (T(-786)C in the promoter, the VNTR in intron 4, and the Glu298Asp variant in exon 7) in 136 black and 154 white subjects from a Brazilian population, which is very heterogeneous. We also estimated the haplotype frequency and evaluated associations between these variants. The Asp298 variant was more common in whites (32.8%) than in blacks (15.1%) (P < 0.004). Similarly, the C(-786) variant was more common in whites (41.9%) than in blacks (19.5%) (P < 0.0004). However, the 4a variant was more common in blacks (32.0%) than in whites (17.9%) (P < 0.003). The most common predicted haplotype in both ethnic groups combined only wild-type variants. While the second most common haplotype in blacks includes the variant 4a and the wild-type variants for the remaining polymorphisms, the second most common haplotype in whites includes the variants Asp298 and C(-786) and the wild-type variant for polymorphism in intron 4. The marked interethnic differences that we found in Brazilians are very similar to those previously reported in Americans. These findings strongly suggest a consistent difference in the distribution of eNOS genetic variants in blacks compared with whites and indicate that the interethnic differences do not vary with geographic origin.     

The effects of NOS3 Glu298Asp variant on colorectal cancer risk and progression in Turkish population

Endothelial nitric oxide synthase (eNOS), coded by the gene NOS3, may play an important role in uncontrollable cellular growth in several cancer types. Our study was performed to test the association between Glu298Asp polymorphisms in the NOS3 gene and colorectal cancer risk and progression. In this study, NOS3 Glu298Asp polymorphism was genotyped in 84 patients with colorectal cancer and 99 healthy subjects using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) analysis. There were significant differences in the distribution of NOS3 genotypes and frequencies of the alleles between colorectal cancer patients and controls (P = 0.016, P = 0.006, respectively). The increased frequency of NOS3 Glu298Asp homozygotes genotypes in patients who had advanced tumour stage was statistically significant (P = 0.042). Our findings have suggested that NOS3 Glu298Asp polymorphism might be associated with the risk and progression of colorectal cancer in Turkish population.     

Lack of association between Glu298Asp polymorphism and coronary artery disease in North Indians

Nitric Oxide (NO) is an important molecule carrying number of different functions in humans. Published studies suggest that it may inhibit several key steps involved in the pathogenesis of atherosclerosis. Inhibition or reduction of NO due to Glu298Asp polymorphism may accelerate atherosclerosis. The aim of this study was to determine whether Glu298Asp polymorphism is implicated in the pathogenesis of coronary artery disease (CAD) among North Indian population from the state of Uttar Pradesh, India. We selected 253 CAD patients and 174 healthy, normotensive, non-diabetic controls, which were matched for gender and ethnicity. The Glu298Asp (rs1799983) variant was detected by genotyping subjects, using a polymerase chain reaction followed by restriction fragment length polymorphism. There was no significant difference found in the genotypic and allelic frequencies between patients and controls. Our study indicated that Glu298Asp polymorphism does not play any critical role in the pathogenesis of CAD, at least in North Indian population.     

Modulation of nitric oxide formation by endothelial nitric oxide synthase gene haplotypes

Nitric oxide (NO) is a major regulator of the cardiovascular system. However, the effects of endothelial nitric oxide synthase (eNOS) gene polymorphisms or haplotypes on the circulating concentrations of nitrite (a sensitive marker of NO formation) and cGMP are unknown. Here we examined the effects of eNOS polymorphisms in the promoter region (T-786C), in exon 7 (Glu298Asp), and in intron 4 (4b/4a) and eNOS haplotypes on the plasma levels of nitrite and cGMP. We hypothesized that eNOS haplotypes could have a major impact on NO formation. We genotyped 142 healthy subjects by PCR-RFLP. To assess NO formation, the plasma concentrations of nitrite and cGMP were determined using an ozone-based chemiluminescence assay and an enzyme immunoassay. Haplotypes were inferred using the PHASE 2.1 program. No significant differences were found in age, body mass index, systolic and diastolic arterial blood pressure, heart rate, total cholesterol, triglycerides, cGMP, or nitrite among the genotype groups for the three polymorphisms studied here (all p>0.05). Interestingly, the C-4b-Glu haplotype was associated with lower plasma nitrite concentrations than those found in the other haplotype groups (p<0.05), but not with different cGMP levels (p>0.05). These findings suggest that eNOS gene variants combined within a specific haplotype modulate NO formation, although individual eNOS polymorphisms probably do not have major effects.     

Association of polymorphisms of endothelial nitric oxide synthase (eNOS) gene with the risk of primary open angle glaucoma in a Brazilian population

The present study aimed to investigate the association of endothelial nitric oxide synthase (eNOS) gene polymorphisms with primary open angle glaucoma (POAG). We conducted a case-control study that included 90 patients with POAG and 127 healthy controls whose blood samples were genotyped for the functional polymorphisms T-786C and Glu298Asp of the eNOS gene by Taqman fluorescent allelic discrimination assay. The T-786C polymorphism was significantly associated as a risk factor for POAG among women (OR: 2.28; 95% CI: 1.11 to 4.70, p=0.024) and marginally associated to the risk of POAG in the patients ≥52 years of age at diagnosis (OR: 2.11; 95% CI: 0.98 to 4.55, p=0,055). However, these results was not confirmed after adjustments for gender, age, self-declared skin color, tobacco smoking and eNOS genotypes by multivariate logistic regression model (OR: 2.08; 95% CI: 0.87 to 5.01, p=0.101 and OR: 2.20; 95% CI: 0.95 to 5.12, p=0.067, respectively). The haplotype CG of T-786C and Glu298Asp showed a borderline association with risk of POAG in the overall analysis (OR: 1.76; 95% CI: 0.98 to 3.14, p=0.055) and among women (OR: 2.02; 95% CI: 0.98 to 4.16, p=0.052). Furthermore, the CG haplotype was significantly associated with the development of POAG for the age at diagnosis group ≥52 years (OR: 3.48; 95% CI: 1.54 to 7.84, p=0.002).We suggested that haplotypes of the polymorphisms T-786C and Glu298Asp of eNOS may interact with gender and age in modulating the risk of POAG.     

Endothelial nitric oxide synthase haplotypes associated with aura in patients with migraine

There is strong evidence implicating nitric oxide (NO) in the pathophysiology of migraine and aura. Therefore, genetic polymorphisms in the endothelial NO synthase (eNOS) gene have been studied as candidate markers for migraine susceptibility. We compared for the first time the distribution of eNOS haplotypes including the three clinically relevant eNOS polymorphisms (T(-786)C in the promoter, rs2070744; Glu298Asp in exon 7, rs1799983; and a 27?bp variable number of tandem repeats in intron 4) and two additional tagging single-nucleotide polymorphisms (rs3918226 and rs743506) in 178 women with migraine (134 without aura and 44 with aura) and 117 healthy controls (control group). Genotypes were determined by TaqMan allele discrimination assay, real-time polymerase chain reaction, and polymerase chain reaction followed by fragment separation by electrophoresis. The GA (rs743506) genotype was more common in the control group than in women with migraine (odds ratio?=?0.47, 95% confidence interval [CI]?=?0.29-0.78, p?相似文献   

Acidic hydrolysis as a mechanism for the cleavage of the Glu(298)-->Asp variant of human endothelial nitric-oxide synthase

The 894G-->T polymorphism within exon 7 of the human endothelial nitric-oxide synthase (eNOS) gene codes for glutamate or aspartate, respectively, at residue 298 and has been associated with several diseases of cardiovascular origin. A recent report indicates that Asp(298)-eNOS (E298D) is cleaved intracellularly to 100- and 35-kDa fragments, suggesting a mechanism for reduced endothelial function. Here we have documented the precise cleavage site of the E298D variant as a unique aspartyl-prolyl (Asp(298)--Pro(299)) bond not seen in wild-type eNOS (Glu(298)). We show that E298D-eNOS, as isolated from cells and in vitro, is susceptible to acidic hydrolysis, and the 100-kDa fragment can be generated ex vivo by increasing temperature at low pH. Importantly, cleavage of E298D was eliminated using a sample buffer system designed to limit acidic hydrolysis of Asp--Pro bonds. These results argue against intracellular processing of E298D-eNOS and suggest that previously described fragmentation of E298D could be a product of sample preparation. We also found that eNOS turnover, NO production, and the susceptibility to cellular stress were not different in cells expressing WT versus E298D-eNOS. Finally, enzyme activities were identical for the respective recombinant enzymes. Thus, intracellular cleavage mechanisms are unlikely to account for associations between the exon 7 polymorphism and cardiovascular diseases.