Effect of the G-308A polymorphism of the tumor necrosis factor alpha gene on the risk of ischemic heart disease and ischemic stroke: a meta-analysis

Estimating the role of single-nucleotide polymorphism (rs1800629)-308 G/A of TNF-alpha gene as genetic marker associated with angina pectoris in a sample of Iraqi patients

BACKGROUND

Angina pectoris (AP) occurs when oxygen and other nutrients are insufficient to meet the metabolic needs of the heart muscle. Stable angina is the most common, while the unstable angina is less frequent. Tumor necrosis factor alpha (TNF-alpha) is a pleiotropic cytokine plays a vital function in the immune response regulation. TNF gene cluster contains many polymorphisms; the most commonly investigated polymorphism is the rs1800629 SNP. This SNP, located at - 308 position with regard to the TNF promoter region, replaces guanine (G) with adenine (A), with the allelic types - 308 G/A, and has been linked to a variety of inflammatory condition and autoimmune diseases. The - 308 G/A SNP was investigated in AP and interconnected to the TNF level to figure out the responsibilities of TNF-alpha gene polymorphism in the pathogenesis of AP.

METHOD

The current work design as a case-control study that involves 300 participant divided to 200 patients evaluated as (stable angina n = 100 and unstable angina n = 100) compared with 100 apparently healthy control subjects. The serum level of TNF-alpha was assessed via enzyme-linked immunosorbent assay (ELISA)/sandwich method. The genotype and allele frequency distribution of TNF-alpha rs1800629 gene polymorphism were investigated by TaqMan probe of allelic discrimination method.

RESULTS

The levels of TNF-alpha were significantly higher in patients with stable and unstable angina pectoris in comparison with controls. The deviation from Hardy-Weinberg equilibrium (HWE) of TNF-alpha genotypes was obvious in control and unstable angina pectoris groups. Moreover, the significant differences between patients with AP and controls under the five genetic models consider the association between TNF-alpha (rs1800629) - 308 G/A and AP with OR > 1. However, data analysis of allelic and genotypic of (rs1800629) - 308 G/A revealed higher significantly differences of GG homozygous and GA heterozygous proportions between stable angina patients and control. The A allele was more represented as etiological allele, and G allele was represented as protective allele. The serum levels of TNF-alpha were significantly higher in subjects with genetically mutated AA genotypes than in subjects with wild GG genotypes in the study groups. ROC curve analysis found the best cutoff value of TNF-alpha level was 77.25 pg/ml.

CONCLUSION

As the results, our data observed a linked of TNF-alpha (rs1800629) - 308 G/A genetic variant with angina pectoris patients, and the A allele has been linked to the production or expression of TNF-alpha serum level and represented an etiological factor of angina pectoris.

Application of Genome-Wide Association Studies in Coronary Artery Disease

Coronary artery disease (CAD) is a complex disease caused by the combination of environmental and genetic factors. It is one of the leading causes of death and disability in the world. Much research has been focussed on CAD genetic mechanism. In recent years, genome-wide association study (GWAS) has developed rapidly around the world. Medical researchers around the world have successfully discovered a series of CAD genetic susceptibility genes or susceptible loci using medical research strategies, leading CAD research toward a new stage. This paper briefly summarizes the important progress made by GWAS for CAD in the world in recent years, and then analyzes the challenges faced by GWAS at this stage and the development trend of future research, to promote the transformation of genetic research results into clinical practice and provide guidance for further exploration of the genetic mechanism of CAD.

Impact of Myocardial Revascularization Method on Smoking Cessation: Coronary Artery Bypass Grafting versus Percutaneous Coronary Intervention

Introduction

Smoking is a serious public health issue, being a precursor of heart disease and a predictor of sudden death due to myocardial ischemia. Major events in the patient's health can lead to radical changes in habits and the choice for different myocardial revascularization methods might differently impact smoking cessation and relapse.

Objective

To study the rate and perpetuation of smoking cessation after myocardial revascularization comparing coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI).

Methods

Smokers submitted to myocardial revascularization were divided into CABG and PCI groups. The research was conducted through interviews at the Hospital Santa Lucinda outpatient clinic. Patients with smoking cessation longer than 90 days before hospital admission, combined procedures, hospital readmission before 360 days after discharge, cases of death at any time, and emergency procedures were excluded from the study. The start of the smoking cessation period was determined as just after hospital discharge, with a follow-up of 12 months.

Results

The proportion of patients reporting smoking relapse was significantly lower in the CABG than in the PCI group at 30 (11.1% vs. 20.8%; P=0.039) and at 180 days (23.1% vs. 41.5%; P=0.002), but no differences were observed between the two groups at 360 days after hospital discharge (51.9% vs. 54.1%; P=0.719). High levels of nicotine dependence and passive smoking showed to be important predictors of smoking relapse in the long-term.

Conclusion

The occurrence of a major surgical procedure seems to have beneficial psychological effects, representing an interesting setting for smoking cessation counseling to have higher chances of success.

Tumor necrosis factor-alpha gene polymorphisms and susceptibility to ischemic heart disease: A systematic review and meta-analysis

BACKGROUND

A number of studies had reported the association between tumor necrosis factor-alpha (TNF-α) gene polymorphisms and ischemic heart disease (IHD) risk. However, the results remained controversial. Therefore, we performed a systematic review with multiple meta-analyses to provide the more precise estimations of the relationship.

METHODS

We systematically searched electronic databases (PubMed, the Web of Science, EMBASE, Medline, Chinese National Knowledge Infrastructure, WanFang and ChongQing VIP Database) for relevant studies published up to February 2017. The odds ratios (ORs) and 95% confidence intervals (CIs) were estimated for assessing the association. The present meta-analysis was performed using STATA 12.0 software.

RESULTS

In total, 45 articles with 17,375 cases and 15,375 controls involved were included. Pooled ORs revealed a significant association between TNF-α -308G/A gene polymorphism and IHD (A vs. G: OR = 1.22, 95% CI = 1.10-1.35; (AA + GA) vs. GG: OR = 1.18, 95% CI = 1.03-1.36; (AA vs. (GA+GG): OR = 1.37, 95% CI = 1.08-1.75)), indicating that the TNF-α -308A allele might be an important risk factor for IHD. No association between other TNF-α gene polymorphisms and susceptibility to IHD were observed. No publication bias were found. Sensitivity analyses indicated that our results were stable.

CONCLUSION

The present study indicated a possible association between the TNF-α -308G/A gene polymorphism and IHD risk. However, evidence was limited to confirm the role of TNF-α -238G/A, -857C/T, -863C/A, -1031T/C and other TNF-α gene polymorphisms in the risk of IHD.

Association between Tumor Necrosis Factor-α (-238G/A and -308G/A) Gene Polymorphisms and Risk of Ischemic Stroke: A Meta-Analysis

Tumor necrosis factor-α (TNF-α) is a proinflammatory pleiotropic cytokine which may contribute to the initiation and progression of ischemic stroke (IS). Thus far, numerous studies have been performed to examine the association between -238G/A (rs361525) and -308G/A (rs1800629) polymorphisms in the promoter regions of the TNF-α gene and susceptibility to IS, but results are still conflicting. The aim of this meta-analysis is to provide a relatively comprehensive account of the association between TNF-α -238G/A and -308G/A gene polymorphisms and susceptibility to IS. A literature search for eligible candidate gene studies published before April 20, 2015, was conducted in the PubMed, Medline, EMBASE and Google Scholar databases. The following combinations of main keywords were used: ('Tumor Necrosis Factor-Alpha' or 'TNF-α') and ('ischemic stroke' or 'cerebral infarction' or 'IS') and ('genetic polymorphism' or 'single nucleotide polymorphisms' or 'SNP'). Fixed- or random-effect models were used to estimate the pooled odds ratio (OR) and 95% confidence interval (CI). Meta-analysis was carried out by using RevMan 5.3 software. For TNF-α -238G/A gene polymorphism, 7 case-control studies with a total of 1,846 IS patients and 1,905 controls showed a significant association with susceptibility to IS under a dominant model (AA + GA vs. GG; OR, 1.40; 95% CI, 1.11-1.76; p value 0.004). For TNF-α -308G/A gene polymorphism, 16 case-control studies with a total of 5,651 IS patients and 5,792 controls showed a significant protective association with susceptibility to IS under a dominant model (AA + GA vs. GG; OR, 0.78, 95% CI, 0.63-0.97; p value 0.03). Our meta-analysis shows that TNF-α -238G/A gene polymorphism is more likely to be associated with the risk of IS in Caucasian populations as compared to Asian populations. However, TNF-α -308G/A gene polymorphism is more likely to be protective against IS in Asian populations as compared to Caucasian populations. Further large, well-designed prospective epidemiological studies are needed to confirm these findings.

Tumor necrosis factor-alpha (- 308G/A, + 488G/A, - 857C/T and -1031 T/C) gene polymorphisms and risk of ischemic stroke in north Indian population: A hospital based case-control study

Background

Genetic factors may play a role in the susceptibility of Ischemic stroke (IS). Previous studies have shown that Tumour necrosis factor-α (TNF-α) gene polymorphisms were associated with the risk of IS in multiple ethnicities. The present case–control study tested the hypothesis that genetic polymorphisms of the TNF-α gene may affect the risk of IS in North Indian population. We investigated the association of four single nucleotide polymorphisms (− 308G/A, + 488G/A, − 857C/T and -1031 T/C) within TNF-α gene promoter and their haplotypes with the risk of IS.

Methods

IS was classified using the Trial of Org 10,172 in Acute Stroke Treatment (TOAST) classification. Genotyping was performed for 250 IS patients and 250 age- and sex-matched IS free controls by using SNaPshot technique. Multivariate logistic regression was used to control the confounding effects of demographic and risk factor variables. Haplotype analyses were done by using PHASE software and Linkage disequilibrium (LD) analyses were done by using Haploview version 4.2 software.

Results

An independent association between TNF-α + 488G/A (OR = 2.59; 95%CI 1.46 to 4.60; p = 0.001) and -857C/T (OR = 1.77; 95%CI 1.01 to 3.11; p < 0.04) and risk of IS was observed under dominant model. However, no significant association between -308G/A and -1031 T/C gene polymorphisms and risk of IS was observed. Haplotype analysis showed that A308-G488-C857-T1031 haplotypes were significantly associated with the increased risk of IS [OR = 1.66; 95%CI 1.02 to 2.71; p = 0.003]. Strong linkage disequilibrium (LD) was observed for + 488G/A and -857C/T (D’ = 0.41, r² = 0.004).

Conclusions

Two SNPs (+ 488G/A and -857C/T) of TNF-α gene and their haplotypes are significantly associated with the risk of IS in the population enrolled from North India. Our findings indicate that polymorphisms and haplotypes of TNF-α gene may be used as a genetic marker for identifying individuals at increased risk for developing IS.

Tumor necrosis factor-alpha G-238A polymorphism and coronary artery disease risk: a meta-analysis of 4,222 patients and 4,832 controls

BACKGROUND

The aim of the present study was to investigate the association between tumor necrosis factor-alpha (TNF-α) gene G-238A polymorphism and risk of coronary artery disease (CAD) using a meta-analytical approach.

METHODS

The PubMed and Embase databases were searched for relevant publications up to January 13, 2015. Four authors (XPH, XDZ, XTZ, and ZJZ) independently selected the studies, extracted, and analyzed the data using the Comprehensive Meta-Analysis software. The sensitivity and subgroups analyses were also performed. Either a fixed effects or a random effects model was used to estimate pooled odds ratios (ORs) and their 95% confidence intervals (CIs).

RESULTS

Finally, ten articles including eleven case-control studies involving 4,222 patients and 4,832 controls were yielded. The results indicated no significant association between G-238A polymorphism and CAD risk (A vs G: OR =1.08, 95% CI =0.89-1.30; AA vs GG: OR =1.15, 95% CI =0.59-2.25; GA vs GG: OR =1.14, 95% CI =0.88-1.48; AA vs [GG + GA]: OR =1.09, 95% CI =0.56-2.14; (GA + AA) vs GG: OR =1.11, 95% CI =0.90-1.38). In the subgroup analyses, similar results were obtained with overall populations. The sensitivity analyses showed that the overall results were robust. No publication bias was detected.

CONCLUSION

Based on current evidence, we can conclude that TNF-α G-238A polymorphism might not be associated with CAD risk.

Systematic Review by Multivariate Meta-analyses on the Possible Role of Tumor Necrosis Factor-α Gene Polymorphisms in Association with Ischemic Stroke

A number of studies have investigated the association between tumor necrosis factor (TNF)-α gene polymorphisms and ischemic stroke susceptibility. However, results of different individual studies are often inconsistent. To provide a more robust evaluation of the association between polymorphisms of the TNF-α gene and ischemic stroke risk, we performed a systematic review with multivariate meta-analyses. PubMed, Embase, CNKI, and WanFang databases were searched up to December 20, 2014. Two reviewers independently extracted information and assessed quality of included studies after all the eligible studies were identified. Afterward, multivariate meta-analyses were performed using Stata 13. The estimation of polymorphisms and disease risk was presented by odds ratios (ORs) and corresponding 95 % confidence intervals (CIs). Forty-nine eligible case-control studies from 25 articles that explored the association between 10 TNF-α polymorphisms and ischemic stroke were indentified from aforementioned databases. The results of multivariate meta-analysis showed a significant association between -238G/A polymorphism (4760 patients and 4389 controls) and ischemic stroke risk in heterozygotes compared with wild genotype (AG vs. GG: OR 1.44, 95 % CI 1.11-1.87; AA vs. GG: OR 1.98, 95 % CI 0.73-5.40). No significant association of -308G/A, -857C/T, and -1031T/C polymorphisms was observed. The results of stratification analyses of -238G/A polymorphism showed that the AG genotype only increased the risk of ischemic stroke in Asians compared to GG genotype. No additional significant association was observed in this study. In conclusion, the present systematic review and meta-analysis support a prominent role of the TNF-α -238G/A polymorphism in the risk of ischemic stroke in Asian adults only, but do not support the role of -308G/A, -857C/T, -1031T/C, -244G/A, -367G/A, -646G/A, -806C/T, -863C/A, and +448G/A in the risk of ischemic stroke. The current evidence warrants further studies with high quality and large sample size to confirm.

Predictive Potential of Twenty-Two Biochemical Biomarkers for Coronary Artery Disease in Type 2 Diabetes Mellitus

We investigated the potential of a panel of 22 biomarkers to predict the presence of coronary artery disease (CAD) in type 2 diabetes mellitus (DM2) patients. The study enrolled 96 DM2 patients with (n = 75) and without (n = 21) evidence of CAD. We assessed a biochemical profile that included 22 biomarkers: total cholesterol, LDL, HDL, LDL/HDL, triglycerides, glucose, glycated hemoglobin, fructosamine, homocysteine, cysteine, methionine, reduced glutathione, oxidized glutathione, reduced glutathione/oxidized glutathione, L-arginine, asymmetric dimethyl-L-arginine, symmetric dimethyl-L-arginine, asymmetric dimethyl-L-arginine/L-arginine, nitrate plus nitrite, S-nitrosothiols, nitrotyrosine, and n-acetyl-β-glucosaminidase. Prediction models were built using logistic regression models. We found that eight biomarkers (methionine, nitratate plus nitrite, n-acetyl-β-glucosaminidase, BMI, LDL, HDL, reduced glutathione, and L-arginine/asymmetric dimethyl-L-arginine) along with gender and BMI were significantly associated with the odds of CAD in DM2. These preliminary findings support the notion that emerging biochemical markers might be used for CAD prediction in patients with DM2. Our findings warrant further investigation with large, well-designed studies.

Efficacy comparison between minimally invasive and conventional surgery for lumbar disc herniation in Chinese Han population: a meta-analysis

STUDY DESIGN

The pooled data were analyzed using RevMan 5.2 software.

OBJECTIVES

The aim was to compare the efficacy of minimally invasive and conventional surgery for lumbar disc herniation (LDH) in Chinese Han population.

SETTING

China.

METHODS

An electronic search up to November 2013 was performed to retrieve all relevant articles. The overall standardized mean difference (SMD) for continuous outcomes and odds ratio (OR) for dichotomous variables as well as their 95% confidence intervals (CIs) were calculated to compare the efficacy of minimally invasive and conventional surgery.

RESULTS

A total of 23 studies involving 1913 patients treated by minimally invasive surgery and 2295 patients treated by conversational surgery were included in this meta-analysis. The overall estimate indicated that minimally invasive surgery could significantly decrease the hospitalization time (SMD = -2.03, 95% CI, -2.49 to 1.56, P < 0.0001), blood loss (SMD = -2.65, 95% CI -3.33 to 1.97, P < 0.0001), incision length (SMD = -3.57, 95% CI, -4.39 to 2.75, P < 0.0001), recurrence rate (odds ratio (OR) = 0.22, 95 CI: 0.08-0.60, P = 0.003) and complications (OR = 0.47, 95% CI: 0.25-0.92, P = 0.03) and increase the postoperative excellent rate (OR = 1.82, 95% CI, 1.44-2.31, P < 0.0001) compared with conventional surgery. In addition, the pooled data showed that there was no statistically significant difference in the operative time (SMD = -0.58, 95% CI, -1.32 to 0.15, P = 0.12) between LDH patients treated by minimally invasive and conventional surgery.

CONCLUSION

In conclusion, minimally invasive surgery was a more safe and effective treatment for treating LDH in Chinese Han population when compared with conventional surgery.

Epigenetic patterns of two gene promoters (TNF-α and PON) in stroke considering obesity condition and dietary intake

Some causal bases of stroke remain unclear, but the nutritional effects on the epigenetic regulation of different genes may be involved. The aim was to assess the impact of epigenetic processes of human tumor necrosis factor (TNF-α) and paraoxonase (PON) promoters in the susceptibility to stroke when considering body composition and dietary intake. Twenty-four patients (12 non-stroke/12 stroke) were matched by sex (12 male/12 female), age (mean 70 ± 12 years old), and BMI (12 normal-weight/12 obese; mean 28.1 ± 6.7 kg/m(2)). Blood cell DNA was isolated and DNA methylation levels of TNF-α (-186 to +349 bp) and PON (-231 to +250 bp) promoters were analyzed by the Sequenom EpiTYPER approach. Histone modifications (H3K9ac and H3K4me3) were analyzed also by chromatin immunoprecipitation in a region of TNF-α (-297 to -185). Total TNF-α promoter methylation was lower in stroke patients (p < 0.001) and showed no interaction with body composition (p = 0.807). TNF-α and PON total methylation levels correlated each other (r = 0.44; p = 0.031), especially in stroke patients (r = 0.72; p = 0.008). The +309 CpG methylation site from TNF-α promoter was related to body weight (p = 0.027) and the region containing three CpGs (from -170 to -162 bp) to the percentage of lipid intake and dietary indexes (p < 0.05) in non-stroke patients. The methylation of PON +15 and +241 CpGs was related to body weight (p = 0.021), waist circumference (p = 0.020), and energy intake (p = 0.018), whereas +214 was associated to the quality of the diet (p < 0.05) in non-stroke patients. When comparing stroke vs non-stroke patients regarding the histone modifications analyzed at TNF-α promoter, no changes were found, although a significant association was identified between circulating TNF-α level and H3K9ac with H3K4me3. TNF-α and PON promoter methylation levels could be involved in the susceptibility to stroke and obesity outcome, respectively. The dietary intake and body composition may influence this epigenetic regulation in non-stroke patients.

Impact of haplotypes of TNF in the natural course of infective endocarditis

Based on previous findings for the role of single nucleotide polymorphisms (SNPs) of TNF for the predisposition for bloodstream infections, this study investigates the role of these SNPs at the promoter positions -376, -308, -238 in infective endocarditis (IE). In a case-control study, 83 patients with IE and 83 controls were enrolled. Blood genotyping for the presence of G or A alleles of the three SNPs was carried out using restriction fragment length polymorphisms. Haplotypes were calculated. Patients were mostly infected by Staphylococcus aureus (32.5%) and by species of enterococci (14.3%) and streptococci (14.3%). Carriage of the minor frequency A alleles at -238 of the promoter region of TNF was greater than in controls (8.4% versus 1.2%, p 0.003). The presence of any of the three GGA/GAA/AGA haplotypes was more frequent in patients with IE (OR 8.22, 95CI% 1.8-37.4, p 0.001). After multivariate logistic regression analysis, it was found that the only factor related to fatal outcome was carriage of the wild-type GGG haplotype (OR, 3.29, 95CI%, 1.05-10.29, p 0.04). GGA, AGA and GAA haplotypes were more frequent in patients with IE than in controls, suggesting a predisposition for IE and a potential protective role against fatal outcome, as the wild-type GGG haplotype was independently related with death.

Lack of association between a functional variant of the BRCA-1 related associated protein (BRAP) gene and ischemic stroke

Background

Atherosclerosis shares common pathogenic features with myocardial infarction (MI) and ischemic stroke. BRCA-1 associated protein (BRAP), a newly identified risk gene for MI, aggravates the inflammatory response in atherosclerosis. The aim of this study was to test the association between the BRAP gene and stroke in a Taiwanese population.

Methods

A total of 1,074 stroke patients and 1,936 controls were genotyped for the functional SNP rs11066001. In our previous studies, the rare allele of this SNP has been repeatedly shown to exert a recessive effect. Therefore, in the current study, we tested for the same recessive model. First, the genotype distributions between all the controls and all the stroke cases were compared. Then to reduce heterogeneity, we explored several population subsets by selecting young stroke subjects (using 45 years of age as the cutoff point), age- and sex-comparable controls, plaque-free controls, and stroke subtypes.

Results

We did not find any significant association for the entire data set (OR = 0.94, p = 0.74) or for the subset analyses using age- and sex-comparable controls (p = 0.70) and plaque-free controls (p = 0.91). Analyses of the four stroke subtypes also failed to show any significant associations (p = 0.42 – 0.98). For both young and old subjects, the GG genotype of rs11066001 was similar in the stroke cases and unmatched controls (8.1% vs. 9.4% in young subjects and 8.0% vs. 7.8% in old subjects). Comparing stroke cases with plaque-free controls also failed to find any significant association.

Conclusions

The BRAP polymorphism may not play an important role in ischemic stroke in the studied population.

Polymorphism of tumor necrosis factor alpha (TNF-alpha) gene promoter, circulating TNF-alpha level, and cardiovascular risk factor for ischemic stroke

Background

Tumor necrosis factor-α (TNF-α) is one of the most typical pro-inflammatory cytokines with both beneficial and destructive properties for the central nervous system. Increasing evidences have demonstrated the important role of TNF-α in the development of ischemic stroke, but studies examining the possible association with stroke or direct functional effects of polymorphisms in TNF-α have been contradictory.

Findings

In this study, a 2-kb length of the proximal promoter of the TNF-α was screened and four polymorphisms were investigated in the case–control study. Our data confirmed the association between -308G/A variant with stroke in 1,388 stroke patients and 1,027 controls and replicated in an independent population of 961 stroke patients and 821 controls (odds ratio (OR) = 1.34, 95% confidence interval (CI) =1.02 to 1.77 and OR = 1.56, 95% CI = 1.09 to 2.23, respectively). To reconcile the association between polymorphisms and stroke and to give a comprehensive picture of the genetic architecture of this important gene, we performed a meta-analysis of 15 published studies in an Asian population. Our results demonstrated an association between rs1800629 and ischemic stroke (OR = 1.43, 95% CI = 1.21 to 1.69). Another meta-analysis results of 14 studies demonstrated that ischemic stroke patients have higher serum TNF-α level than the control subjects (standardized mean difference (SMD) = 2.33, 95% CI = 1.85 to 2.81). In vitro evaluation of potential interaction between variants of the TNF-α gene (−308G/A, -857C/T, and -1031T/C) demonstrated that these three polymorphisms could interact together to determine the overall activity of the TNF-α gene.

Conclusions

These findings strongly implicate the involvement of TNF-α in the pathogenesis of stroke.

Association between the angiotensinogen gene T174M polymorphism and hypertension risk in the Chinese population: a meta-analysis

No consensus has been reached on the association between the angiotensinogen gene polymorphism T174M and hypertension risk in the Chinese population. We conducted a meta-analysis to systematically pursue their possible association. Case-control studies in the Chinese and English publications were identified by searching the MEDLINE, EMBASE, CBM, CNKI, Wanfang and VIP databases. The fixed-effects model and the random-effects model were applied for dichotomous outcomes to combine the results of the individual studies. After this, we selected 16 studies that met the inclusion criteria. In total, the selected studies contributed a study population containing 3828 hypertensive patients and 3251 normotensive controls. We found no statistical association between the T174M polymorphism and hypertension risk in all subjects, in a Han Chinese subgroup or in non-Han Chinese minorities. However, a statistically significant association was observed between the T174M polymorphism and a hypertensive group (systolic blood pressure ≥160 mm Hg and/or diastolic blood pressure ≥95 mm Hg) in the dominant genetic model (MM+MT vs. TT: P=0.03, odds ratio=1.71, 95% confidence interval 1.07-2.74, P(heterogeneity)=0.27, I(2)=24%, fixed-effects model). No evidence of publication bias was observed. More studies, especially studies stratified for different stages of hypertension, should be performed in the future to fully examine this question. Studies investigating gene-gene interactions, gene-environment interactions, as well as their mutual interactions will also be important.

Association of TNF-857C>T, TNFRSF1A36A>G, and TNFRSF1B676T>G Polymorphisms with Ischemic Stroke in a Greek Population

Background. The role of genetic factors in the predisposition to develop ischemic stroke has been assessed by previous studies. The main goal of the current study was to determine any possible role of TNF-857C>T,TNFRSF1A36A>G, and TNFRSF1B676T>G polymorphisms in risk for stroke. Materials and Methods. One hundred seventy-three patients with first ever ischemic stroke of solely atherosclerotic etiology in Northwest Greece and a control group of 179 healthy unrelated subjects were evaluated. Results. TNFα-857TT, TNFR136AA, and TNFR2676TT genotypes were significantly increased in the patient group compared to controls (P = .008, OR = 2.47 (1.26–4.84), P = .005, OR = 1.97 (1.22–3.17), and P = .003, OR = 2.2 (1.43–3.37), resp.). In addition, the TNFR136A and the TNFR2676T alleles were found significantly increased in patients compared to controls (P = .009, OR = 1.48 (1.1–2) and P = .001, OR = 1.75 (1.25–2.46), resp.). Conclusion. The high incidence of these genotypes and alleles in patient group suggests that they are potentially predisposing factors for stroke in the Greek population studied. Large-scale multicenter controlled studies are needed to verify these polymorphisms effects on stroke susceptibility.

ADRB2 and LEPR gene polymorphisms: synergistic effects on the risk of obesity in Japanese

The objective of the present study was to validate a recently reported synergistic effect between variants located in the leptin receptor (LEPR) gene and in the β-2 adrenergic receptor (ADRB2) gene on the risk of overweight/obesity. We studied a middle-aged/elderly sample of 4,193 nondiabetic Japanese subjects stratified according gender (1,911 women and 2,282 men). The LEPR Gln223Arg (rs1137101) variant as well as both ADRB2 Arg16Gly (rs1042713) and Gln27Glu (rs1042714) polymorphisms were analyzed. The primary outcome was the risk of overweight/obesity defined as BMI ≥25 kg/m(2), whereas secondary outcomes included the risk of a BMI ≥27 kg/m(2) and BMI as a continuous variable. None of the studied polymorphisms showed statistically significant individual effects, regardless of the group or phenotype studied. Haplotype analysis also did not disclose any associations of ADRB2 polymorphisms with BMI. However, dimensionality reduction-based models confirmed significant interactions among the investigated variants for BMI as a continuous variable as well as for the risk of obesity defined as BMI ≥27 kg/m(2). All disclosed interactions were found in men only. Our results provide external validation for a male specific ADRB2-LEPR interaction effect on the risk of overweight/obesity, but indicate that effect sizes associated with these interactions may be smaller in the population studied.

Multilocus analyses of seven candidate genes suggest interacting pathways for obesity-related traits in Brazilian populations

We investigated whether variants in major candidate genes for food intake and body weight regulation contribute to obesity-related traits under a multilocus perspective. We studied 375 Brazilian subjects from partially isolated African-derived populations (quilombos). Seven variants displaying conflicting results in previous reports and supposedly implicated in the susceptibility of obesity-related phenotypes were investigated: β2-adrenergic receptor (ADRB2) (Arg16Gly), insulin induced gene 2 (INSIG2) (rs7566605), leptin (LEP) (A19G), LEP receptor (LEPR) (Gln223Arg), perilipin (PLIN) (6209T > C), peroxisome proliferator-activated receptor-γ (PPARG) (Pro12Ala), and resistin (RETN) (-420 C > G). Regression models as well as generalized multifactor dimensionality reduction (GMDR) were employed to test the contribution of individual effects and higher-order interactions to BMI and waist-hip ratio (WHR) variation and risk of overweight/obesity. The best multilocus association signal identified in the quilombos was further examined in an independent sample of 334 Brazilian subjects of European ancestry. In quilombos, only the PPARG polymorphism displayed significant individual effects (WHR variation, P = 0.028). No association was observed either with the risk of overweight/obesity (BMI ≥ 25 kg/m2), risk of obesity alone (BMI ≥ 30 kg/m2) or BMI variation. However, GMDR analyses revealed an interaction between the LEPR and ADRB2 polymorphisms (P = 0.009) as well as a third-order effect involving the latter two variants plus INSIG2 (P = 0.034) with overweight/obesity. Assessment of the LEPR-ADRB2 interaction in the second sample indicated a marginally significant association (P = 0.0724), which was further verified to be limited to men (P = 0.0118). Together, our findings suggest evidence for a two-locus interaction between the LEPR Gln223Arg and ADRB2 Arg16Gly variants in the risk of overweight/obesity, and highlight further the importance of multilocus effects in the genetic component of obesity.

Studies of gene variants related to inflammation, oxidative stress, dyslipidemia, and obesity: implications for a nutrigenetic approach

Obesity is currently considered a serious public health issue due to its strong impact on health, economy, and quality of life. It is considered a chronic low-grade inflammation state and is directly involved in the genesis of metabolic disturbances, such as insulin resistance and dyslipidemia, which are well-known risk factors for cardiovascular disease. Furthermore, there is evidence that genetic variation that predisposes to inflammation and metabolic disturbances could interact with environmental factors, such as diet, modulating individual susceptibility to developing these conditions. This paper aims to review the possible interactions between diet and single-nucleotide polymorphisms (SNPs) in genes implicated on the inflammatory response, lipoprotein metabolism, and oxidative status. Therefore, the impact of genetic variants of the peroxisome proliferator-activated receptor-(PPAR-)gamma, tumor necrosis factor-(TNF-)alpha, interleukin (IL)-1, IL-6, apolipoprotein (Apo) A1, Apo A2, Apo A5, Apo E, glutathione peroxidases 1, 2, and 4, and selenoprotein P exposed to variations on diet composition is described.

TNFA -308 (rs1800629) polymorphism is associated with a higher risk of cardiovascular disease in patients with rheumatoid arthritis

OBJECTIVE

To assess the influence of the TNFA rs1800629 (G > A) polymorphism in the risk of cardiovascular (CV) disease and subclinical atherosclerosis in patients with rheumatoid arthritis (RA).

METHODS

587 patients fulfilling the 1987 American College of Rheumatology classification criteria for RA were studied. Patients were genotyped for the TNFA rs1800629 polymorphism using predesigned TaqMan single nucleotide polymorphism genotyping assay. Also, HLA-DRB1 genotyping was performed using molecular based methods. Carotid artery intima-media thickness, flow-mediated endothelium-dependent and endothelium independent vasodilatation, used as surrogate markers of subclinical atherosclerosis, were measured in a subgroup of patients.

RESULTS

We observed a higher frequency of carriers of the minor allele A among the patients with CV disease (with 37.6% vs. without 27.9%, p = 0.06, OR 1.56 [95% confidence interval-CI 0.95-2.54]). Carriers of the minor allele A exhibited a higher risk of CV events after adjustment for demographic and traditional CV risk factors (p = 0.023, HR 1.72 [95% CI 1.076-2.74]). Also, a significant interaction between this polymorphism and the presence of the rheumatoid shared epitope (SE) was observed (p = 0.024). Due to this, the association between carriers of the minor allele A and CV disease was only present in carriers of the SE, even after adjustment (p = 0.001, HR 2.43 [95% CI 1.41-4.19]). No significant association between the TNFA variant and the surrogate markers of subclinical atherosclerosis was observed.

CONCLUSION

Our results show that TNFA rs1800629 gene polymorphism is associated with predisposition to CV complications in patients with RA. This predisposition is restricted to individuals carrying the rheumatoid SE.

Tumor necrosis factor-alpha G-308A gene polymorphism and coronary heart disease susceptibility: an updated meta-analysis

PURPOSE

Several studies have reported apparently conflicting findings for the effects of tumor necrosis factor-alpha (TNF-α) G-308A polymorphism on coronary heart disease (CHD) susceptibility. We undertook a systematic review and meta-analysis to investigate the association between this gene variant and CHD predisposition.

METHODS

We systematically searched electronic databases (Medline, EMbase, Chinese BioMedical, BIOSIS, Global Health, PsycINFO, Allied and Complementary Medicine Database, Cochrane Library, HuGE Navigator, and British Nursing) for relevant studies published between 1947 and October, 2010. Summarized estimation of odds ratio (OR) and 95% confidence interval (CI) were calculated. Publication bias and heterogeneity among studies were explored.

RESULTS

We identified 24 studies providing data for 9 921 cases and 7 944 controls. Pooled analysis based on ORs adjusted by CHD risk factors showed that carrying the TNF-α gene A variant conferred a 1.5-fold increased risk of developing CHD (AG+AA vs. GG, OR = 1.50, 95% CI: 1.23-1.77) in Caucasian population. No significant association between the gene polymorphism and CHD risk could be found in other ethnic groups.

CONCLUSIONS

It is probable that carrying the A variant is associated with CHD risk in Caucasians but not in Asians, Indians, or Africans. Further studies are merited to assess the association in greater details, especially in Asians, Indians and Africans.

Impact of cytokine genotype on cardiovascular surrogate markers in hemodialysis patients

BACKGROUND/AIMS

Cytokine gene polymorphisms have been implicated as potential genetic risk factors for cardiovascular diseases (CVDs). Atherosclerosis and left ventricular hypertrophy (LVH) are surrogate markers for CVDs in uremic patients. The aim of this study was to assess the role of cytokine gene polymorphisms in carotid intima-media thickness (CIMT) and left ventricular mass index (LVMI) progression in nondiabetic hemodialysis (HD) patients.

METHODS

About 102 nondiabetic patients on maintenance HD were included in this study. Patients were followed up for 2 years. Genetic polymorphisms of TNF-alpha (-308 G/A, -238A/G) and IL-10 (-1082 A/G, -819 C/T, -592 A/C) were determined by polymerase chain reaction. Biochemical parameters and inflammatory markers and ambulatory blood pressure (BP) measurements were determined during the study period. CIMT and LVMI were also determined at baseline and after the first and second year.

RESULTS

Cardiovascular risk factors did not differ between TNF-alpha -308 high-/low-producer genotype groups. However, CIMT and LVMI progression were detected at higher levels in patients with high-producer genotypes (AA+AG) than in patients with the low-producer genotype (GG) during the study period. The TNF-alpha -308 G/A polymorphism was closely associated with C-reactive protein (CRP), a marker of systemic inflammation in the study population. Analysis also showed that the combination of high production of TNF-alpha and low production of IL-10 was associated with higher average IMT and LVMI progression and elevated average CRP levels compared with a combination of low production of TNF-alpha and high production of IL-10.

CONCLUSION

Polymorphisms in inflammatory genes may represent an additional factor affecting inflammation and CVD progression in nondiabetic HD patients.

Genetics of stroke

Stroke is the second most common cause of death and the most common cause of disability in developed countries. Stroke is a multi-factorial disease caused by a combination of environmental and genetic factors. Numerous epidemiologic studies have documented a significant genetic component in the occurrence of strokes. Genes encoding products involved in lipid metabolism, thrombosis, and inflammation are believed to be potential genetic factors for stroke. Although a large group of candidate genes have been studied, most of the epidemiological results are conflicting. Studies of stroke as a monogenic disease have made huge progress, and animal models serve as an indispensable tool to dissect the complex genetics of stroke. In the present review, we provide insight into the role of in vivo stroke models for the study of stroke genetics.

Implications of genetic polymorphisms in inflammation-induced atherosclerosis

Inflammation is the mainstay of atherosclerosis and is an important governing factor at all stages of the disease process from lesion formation to plaque build-up and final end-stage rupture and thrombosis. An overview of the numerous clinico-epidemiological studies on the association between inflammatory gene polymorphisms and Cardiovascular disease (CVD) and its co-morbidities have shown that the risk associated with any single genotype is modest while the haplotypes, especially those defined on the basis of tag-SNP approach, have better coverage of the gene and show moderately higher impact on disease risk. Nevertheless, even these associations have been inconsistent with low cross-race repeatability. This has been attributed to many plausible causes such as clinical heterogeneity, sample selection criteria, variable genetic landscapes across different ethnic groups, confounding effect of co-morbidities etc. On the other hand, unbiased studies such as the family-based linkage and case-control based associations that have taken into account, thousands of genotypic markers spanning the whole genome, have had the ability to identify novel genetic loci for coronary artery disease. These studies have shown that many inflammatory genes are involved in the regulation of specific biomarkers of inflammation that collectively contribute to the disease-associated risk. In addition, there appears to be considerable cross talk between the different biochemical and metabolic processes. Therefore, consideration of all these factors can build towards an 'atherosclerotic bionetwork' that can refine our quest for developing a robust risk stratification tool for cardiovascular disease.

The genetics of ischaemic stroke

In this review, we discuss the genetic factors in both the aetiology and treatment of ischaemic stroke. We discuss candidate gene association studies, family linkage studies and the more recent whole genome association studies and whole genome expression studies. We also briefly discuss genetic testing for stroke risk and genetic analysis of treatment complications.

Candidate gene polymorphisms for ischemic stroke

BACKGROUND AND PURPOSE

Ischemic stroke (IS) is a multifactorial disorder with strong evidence from twin, family, and animal model studies suggesting a genetic influence on risk and prognosis. Several candidate genes for IS have been proposed, but few have been replicated. We investigated the contribution of 67 candidate genes (369 single nucleotide polymorphisms [SNPs]) on the risk of IS in a North American population of European descent.

METHODS

Two independent studies were performed. In the first, 342 SNPs from 52 candidate genes were genotyped in 307 IS cases and 324 control subjects. The SNPs significantly associated with IS were tested for replication in another cohort of 583 IS cases and 270 control subjects. In the second study, 212 SNPs from 62 candidate genes were analyzed in 710 IS cases with subtyping available and 3751 control subjects.

RESULTS

None of the candidate genes (SNPs) were significantly associated with IS risk independent of known stroke risk factors after correction for multiple hypotheses testing.

CONCLUSIONS

These results are consistent with previous meta-analyses that demonstrate an absence of genetic association of variants in plausible candidate genes with IS risk. Our study suggests that the effect of the investigated SNPs may be weak or restricted to specific populations or IS subtypes.

An assessment of a TNF polymorphic marker for the risk of HCV infection: meta-analysis and a new clinical study design

A number of studies have investigated the association between TNF-alpha -308G/A polymorphism and the risk of HCV infection; the results of these studies are conflict, however. To provide a more definitive conclusion, a meta-analysis combining and summarizing 12 studies was performed. The Mantel-Haenszel and DerSimonian-Laird methods were employed in traditional fixed effects and random effects meta-analysis, respectively. The capability of a Bayesian approach was highlighted in the estimation of a pooled odds ratio and 95% confidence interval, as well as in the calculation of a sample size for the new study design. Heterogeneity and publication bias across the studies were also explored. The results of the meta-analysis (OR=1.179, CI=0.833-1.649) suggest no significant association between TNF-alpha -308G/A polymorphism and susceptibility to HCV infection in the combined populations. However, there was evidence indicating a possible impact of ethnicity (Asian vs. non-Asian populations) on the association evaluated here (beta(ethnicity)=0.293+/-0.271). While the power of existing Asian studies was insufficient to make a statistical statement, the sample size of a new clinical study was estimated (500 subjects with 80% statistical power) for further assessment of an association between TNF-alpha -308G/A polymorphism and risk of HCV infection in Asians.

Association of tumour necrosis factor alpha (TNF-alpha) polymorphisms with Graves' disease: A meta-analysis

OBJECTIVE

To quantitatively summarize the association between tumour necrosis factor alpha (TNF-alpha) gene polymorphisms and Graves' disease.

DESIGN AND METHODS

Relevant studies were identified from the following electronic databases: Cochrane Library, MEDLINE, EMBASE and Chinese Bio-medicine Database. A meta-analysis of relevant studies was performed.

RESULTS

This meta-analysis included 10 case-control studies, which included 2271 Graves' disease cases and 2633 controls. The combined results based on all studies showed that there was significant difference in genotype distribution (-308A/G; -308G/G; -863C/C; -863C/A; -1031C/T) between Graves' disease and controls. When stratifying for race, statistically significant results were observed in three genotype distribution (-863C/C; -863C/A; -1031C/T) between Graves' disease and controls among Asians. Statistically significant results were observed in only two genotype distribution (-308A/G; -308G/G) between Graves' disease and controls among Caucasians.

CONCLUSIONS

This meta-analysis suggests that TNF-alpha gene polymorphisms at positions -308 (G-308A), -863 (C-863A), and -1031 (T-1031C) were associated with Graves' disease.

Meta-analysis of the association of 4 angiotensinogen polymorphisms with essential hypertension: a role beyond M235T?

Angiotensinogen (AGT) gene polymorphisms have been linked to increased risk of hypertension, but the data remain controversial. In this study we review the most commonly investigated polymorphisms at the AGT locus (other than M235T) and provide summary estimates regarding their association with essential hypertension, while addressing heterogeneity, as well as publication biases. Data on 26 818 subjects from 46 studies for the 4 most-studied AGT variants (T174M in exon 2 and 3 promoter variants: A-6G, A-20C, and G-217A) were meta-analyzed. Statistically significant associations with hypertension were identified for the T174M (odds ratio [OR]: 1.19; 95% CI: 1.07 to 1.33; P=0.002) and G-217A (OR: 1.37; 95% CI: 1.17 to 1.59; P=0.00006) polymorphisms. A dual but consistent effect was observed for the -20C allele, which was associated with a decreased risk of hypertension in populations of mixed and European ancestries (OR: 0.64; 95% CI: 0.44 to 0.92; P=0.02 and OR: 0.77; 95% CI: 0.65 to 0.91; P=0.003, respectively), but with a 24% increase in the odds of hypertension in Asian subjects (OR: 1.24; 95% CI: 1.04 to 1.48; P=0.02). No association of the A-6G variant with hypertension was detected. Current studies support the notion that single variants at the AGT might modulate the risk of hypertension but indicate caution in interpreting these results because of the putative presence of publication bias and gene-environment interactions.

Advances in the Genetic Basis of Ischemic Stroke

As one of the leading causes of death within both the developed and developing world, stroke is a world-wide problem. About 80% of strokes are ischemic. It is caused by multiple genetic factors, environmental factors, and interactions among these factors. There is a long list of candidate genes that have been studied for a possible association with ischemic stroke. Among the most widely investigated genes are those involved in haemostasis, inflammation, nitric oxide production, homocysteine and lipid metabolism, renin-angiotensin-aldosterone system. Combined link-age/association studies have demonstrated that genes encoding PDE4D and ALOX5AP confer risk for stroke. We review the studies of these genes which may have potential application on the early diagnosis, prevention and treatment ischemic stroke patients.