Exploring Gene-Environment Relationships in Cardiovascular Disease

Reverse expression pattern of sirtuin-1 and histone deacetylase-9 in coronary artery disease

BACKGROUND

SIRT1 and HDAC 9 genes are related to inflammation and may contribute to the pathogenesis of coronary artery disease (CAD). We aimed to evaluate the expression level, methylation profile and polymorphisms of these genes in CAD patients.

METHODS

In this study, 50 CAD patients and 50 healthy individuals were recruited. The expression level change was evaluated using the TaqMan Real-Time PCR method. The methylation of genes promoter and genotyping of polymorphisms were evaluated by the HRM.

RESULTS

The expression level of SIRT1 was reduced while the HDAC9 expression level showed a significant elevation (p < .001). The SIRT1 gene promoter was hypomethylated and the HDAC9 gene promoter was hypermethylated in CAD patients. Also, CG + GG genotype in SIRT1 and both genotypes in the HDAC9 gene were associated with expression change.

CONCLUSIONS

SIRT1 and HDAC9 genes, expression changes can be suggested as a potential biomarker for CAD detection.

Trans-interaction of risk loci 6p24.1 and 10q11.21 is associated with endothelial damage in coronary artery disease

BACKGROUND AND AIMS

Single nucleotide polymorphism rs6903956 has been identified as one of the genetic risk factors for coronary artery disease (CAD). However, rs6903956 lies in a non-coding locus on chromosome 6p24.1. We aim to interrogate the molecular basis of 6p24.1 containing rs6903956 risk alleles in endothelial disease biology.

METHODS AND RESULTS

We generated induced pluripotent stem cells (iPSCs) from CAD patients (AA risk genotype at rs6903956) and non-CAD subjects (GG non-risk genotype at rs6903956). CRISPR-Cas9-based deletions (Δ63-89bp) on 6p24.1, including both rs6903956 and a short tandem repeat variant rs140361069 in linkage disequilibrium, were performed to generate isogenic iPSC-derived endothelial cells. Edited CAD endothelial cells, with removal of 'A' risk alleles, exhibited a global transcriptional downregulation of pathways relating to abnormal vascular physiology and activated endothelial processes. A CXC chemokine ligand on chromosome 10q11.21, CXCL12, was uncovered as a potential effector gene in CAD endothelial cells. Underlying this effect was the preferential inter-chromosomal interaction of 6p24.1 risk locus to a weak promoter of CXCL12, confirmed by chromatin conformation capture assays on our iPSC-derived endothelial cells. Functionally, risk genotypes AA/AG at rs6903956 were associated significantly with elevated levels of circulating damaged endothelial cells in CAD patients. Circulating endothelial cells isolated from patients with risk genotypes AA/AG were also found to have 10 folds higher CXCL12 transcript copies/cell than those with non-risk genotype GG.

CONCLUSIONS

Our study reveals the trans-acting impact of 6p24.1 with another CAD locus on 10q11.21 and is associated with intensified endothelial injury.

Identification of an Epigenetic Signature for Coronary Heart Disease in Postmenopausal Women’s PBMC DNA

Menopause is accompanied with an increased risk of cardiovascular disease. DNA methylation may have a significant impact on postmenopausal women's development of coronary heart disease. DNA methylation alterations in peripheral blood mononuclear cells (PBMCs) from women with coronary heart disease and healthy controls were detected using the Illumina Infinium MethylationEPIC BeadChip platform in this work. We employed Sangerbox technology and the GO and KEGG databases to further study the pathogenesis of coronary heart disease in postmenopausal women. After that, we used functional epigenetic module analysis and Cytoscape to remove the hub genes from the protein–protein interaction networks. Five genes (FOXA2, PTRD, CREB1, CTNAP2, and FBN2) were the hub genes. Lipid accumulation, endothelial cell failure, inflammatory responses, monocyte recruitment and aggregation, and other critical biological processes were all influenced by these genes. Finally, we employed methylation-specific PCR to demonstrate that FOXA2 was methylated at a high level in postmenopausal women with coronary heart disease. To better understand coronary heart disease in postmenopausal women's molecular mechanisms, our study examine the major factors contributing to the state of DNA methylation modification, which will help discover novel diagnostic tools and treatment options.

Identification of genetic loci simultaneously associated with multiple cardiometabolic traits

BACKGROUND AND AIMS

Cardiometabolic disorders (CMD) arise from a constellation of features such as increased adiposity, hyperlipidemia, hypertension and compromised glucose control. Many genetic loci have shown associations with individual CMD-related traits, but no investigations have focused on simultaneously identifying loci showing associations across all domains. We therefore sought to identify loci associated with risk across seven continuous CMD-related traits.

METHODS AND RESULTS

We conducted separate genome-wide association studies (GWAS) for systolic and diastolic blood pressure (SBP/DBP), hemoglobin A1c (HbA1c), low- and high- density lipoprotein cholesterol (LDL-C/HDL-C), waist-to-hip-ratio (WHR), and triglycerides (TGs) in the UK Biobank (N = 356,574-456,823). Multiple loci reached genome-wide levels of significance (N = 145-333) for each trait, but only four loci (in/near VEGFA, GRB14-COBLL1, KLF14, and RGS19-OPRL1) were associated with risk across all seven traits (P < 5 × 10^-8). We sought replication of these four loci in an independent set of seven trait-specific GWAS meta-analyses. GRB14-COBLL1 showed the most consistent replication, revealing nominally significant associations (P < 0.05) with all traits except DBP.

CONCLUSIONS

Our analyses suggest that very few loci are associated in the same direction of risk with traits representing the full spectrum of CMD features. We identified four such loci, and an understanding of the pathways between these loci and CMD risk may eventually identify factors that can be used to identify pathologic disturbances that represent broadly beneficial therapeutic targets.

ATP2B1 genotypes rs2070759 and rs2681472 polymorphisms and risk of hypertension in Saudi population

This study examined an association of ATP2B1 gene polymorphism and hypertension in the Saudi population. The 246 hypertensive cases and 300 healthy human controls were genotyped. The results showed that genotypes rs.207075 (CA + AA) [p = 0.05; OR: 95% CI, 1.5:(1.0 to 2.4) and p = 0.001, OR: 95% CI, 2.4: (1.5 to 4.0) and rs2681472 (CT + TT) [p = 0.05; OR: 95% CI, 1.5 (1.0 to 2.4) and p = 0.006 OR: 95% CI, 2.0 (1.2 to 3.1) respectively] associated with the risk of hypertension. Cases carrying the recessive models: [(CA + AA)/(CT + TT)] and [(AA)/(TT)] genotypes confer a strong susceptibility risk of hypertension [p = 0.002; OR: (95%CI) 1.8 (1.2 to 2.6) and p = 0.001; OR: (95%CI) 2.6 (1.5 to 4.7) respectively]. However, cases with body-mass-index (BMI)<25, carrying homozygous mutant genotypes [AA, rs2070759, p = 0.007; OR: (95%CI) 2.75(1.37 to 5.5) and (TT, rs2681472, p = 0.05; OR: (95%CI) 1.96 (1.03 to 3.72)] as well as A allele of rs2070759 [p = 0.006; OR: (95%CI) 1.62 (1.16 to 2.25)] and T allele of rs2681472, p = 0.04, 1.43(1.03 to 1.98)] showed a significant association with high risk of hypertension. In short, a significant association between ATP2B1 gene polymorphism and risk of hypertension was noticed. In addition, individuals carrying recessive genotypes have greater risk in developing hypertension than those carrying dominant genotypes. Moreover, cases with high-risk BMI associated with ATP2B1 variants may play a critical role in developing hypertension.Supplemental data for this article is available online at https://doi.org/10.1080/15257770.2021.1973034 .

Physical Activity, Obesity, and Hypertension among Adults in a Rapidly Urbanised City

Background

Few studies have explored the relationship between the level of physical activity and the occurrence or prevalence of obesity and hypertension among people residing in urbanised areas.

Method

A cross-sectional study involving a sample of 1,001 adults was conducted. Descriptive statistics were used to describe sociodemographic variables, physical activity levels, body mass index (BMI), and prevalence of hypertension. Logistic regression models were adopted to investigate the relationship between these factors.

Results

A total of 939 respondents who provided valid responses were included. Among them, 56.5% of the participants reported engaging in high levels of physical activity. However, 40.4% of the respondents were classified as overweight or obese, and 31.9% had diagnosed hypertension. After adjusting for sociodemographic factors, logistic regression analysis revealed that physical activity levels were negatively correlated with the prevalence of BMI (OR = 0.564, 95% CI: 0.352-0.905; OR = 0.583, 95% CI: 0.375-0.907) and hypertension (OR = 0.556, 95% CI: 0.348-0.888).

Conclusions

Our study confirms recent evidence regarding the amount of physical activity that is associated with lower prevalence of obesity and hypertension in Pingshan District. Furthermore, different physical activities of various intensity levels had different effects on hypertension. Residents should be encouraged to engage in physical activities and maintain a healthy weight to improve their quality of life.

Genome-wide analysis of DNA methylation and risk of cardiovascular disease in a Chinese population

Background

Systemic studies of association of genome-wide DNA methylated sites with cardiovascular disease (CVD) in prospective cohorts are lacking. Our aim was to identify DNA methylation sites associated with the risk of CVD and further investigate their potential predictive value in CVD development for high-risk subjects.

Methods

We performed an epigenome-wide association study (EWAS) to identify CpGs related to CVD development in a Chinese population.We adopted a nested case–control design based on data from China PEACE Million Persons Project. A total of 83 cases who developed CVD events during follow-up and 83 controls who were matched with cases by age, sex, BMI, ethnicity, medications treatment and behavior risk factors were included in the discovery stage. Genome-wide DNA methylation from whole blood was detected using Infinium Human Methylation EPIC Beadchip (850 K). For significant CpGs [FDR(false discovery rate) < 0.005], we further validated in an independent cohort including 38 cases and 38 controls.

Results

In discovery set, we identified 8 significant CpGs (FDR < 0.005) associated with the risk of CVD after adjustment for cell components, demographic and cardiac risk factors and the first 5 principal components. Two of these identified CpGs (cg06901278 and cg09306458 in UACA) were replicated in another independent set (p < 0.05). Enrichment analysis in 787 individual genes from 1036 CpGs in discovery set revealed a significant enrichment for anatomical structure homeostasis as well as regulation of vesicle-mediated transport. Receiver operating characteristic (ROC) analysis showed that the model combined 8 CVD-related CpGs with baseline characteristics showed much better predictive effect for CVD occurrence compared with the model with baseline characteristics only [AUC (area under the curve) = 0.967, 95% CI (0.942 − 0.991); AUC = 0.621, 95% CI (0.536 − 0.706); p = 9.716E-15].

Conclusions

Our study identified the novel CpGs associated with CVD development and revealed their additional predictive power in the risk of CVD for high-risk subjects.

Supplementary information

The online version contains supplementary material available at 10.1186/s12872-021-02001-w.

Reverse gene-environment interaction approach to identify variants influencing body-mass index in humans

Identifying gene-environment interactions (GxEs) contributing to human cardiometabolic disorders is challenging. Here we apply a reverse GxE candidate search by deriving candidate variants from promoter-enhancer interactions that respond to dietary fatty acid challenge through altered chromatin accessibility in human primary adipocytes. We then test all variants residing in the lipid-responsive open chromatin sites within adipocyte promoter-enhancer contacts for interaction effects between the genotype and dietary saturated fat intake on body mass index (BMI) in the UK Biobank. We discover 14 novel GxE variants in 12 lipid-responsive promoters, including well-known lipid genes (LIPE, CARM1, and PLIN2) and novel genes, such as LDB3, for which we provide further functional and integrative genomics evidence. We further identify 24 GxE variants in enhancers, totaling 38 new GxE variants for BMI in the UK Biobank, demonstrating that molecular genomics data produced in physiologically relevant contexts can discover new functional GxE mechanisms in humans.

The influence of maternal and infant nutrition on cardiometabolic traits: novel findings and future research directions from four Canadian birth cohort studies

A mother's nutritional choices while pregnant may have a great influence on her baby's development in the womb and during infancy. There is evidence that what a mother eats during pregnancy interacts with her genes to affect her child's susceptibility to poor health outcomes including childhood obesity, pre-diabetes, allergy and asthma. Furthermore, after what an infant eats can change his or her intestinal bacteria, which can further influence the development of these poor outcomes. In the present paper, we review the importance of birth cohorts, the formation and early findings from a multi-ethnic birth cohort alliance in Canada and summarise our future research directions for this birth cohort alliance. We summarise a method for harmonising collection and analysis of self-reported dietary data across multiple cohorts and provide examples of how this birth cohort alliance has contributed to our understanding of gestational diabetes risk; ethnic and diet-influences differences in the healthy infant microbiome; and the interplay between diet, ethnicity and birth weight. Ongoing work in this birth cohort alliance will focus on the use of metabolomic profiling to measure dietary intake, discovery of unique diet-gene and diet-epigenome interactions, and qualitative interviews with families of children at risk of metabolic syndrome. Our findings to-date and future areas of research will advance the evidence base that informs dietary guidelines in pregnancy, infancy and childhood, and will be relevant to diverse and high-risk populations of Canada and other high-income countries.

Influence of Body Mass Index on Outcomes of Patients Undergoing Surgery for Acute Aortic Dissection: A Propensity-Matched Analysis

To determine whether body mass index ≥30 kg/m² affects morbidity and mortality rates in patients undergoing surgery for type A acute aortic dissection, we conducted a retrospective study of 201 patients with type A dissection. Patients were divided into 2 groups according to body mass index (BMI): nonobese (BMI, <30 kg/m²; 158 patients) and obese (BMI, ≥30 kg/m²; 43 patients). Propensity score matching was used to reduce selection bias. The overall mortality rate was 19% (38/201 patients). The perioperative mortality rate was higher in the obese group, both in the overall cohort (33% vs 15%; P=0.01) and in the propensity-matched cohort (32% vs 12%; P=0.039). In the propensity-matched cohort, patients with obesity had higher rates of low cardiac output syndrome (26% vs 6%; P=0.045) and pulmonary complications (32% vs 9%; P=0.033) than those without obesity. The overall 5-year survival rates were 52.5% ± 7.8% in the obese group and 70.3% ± 4.4% in the nonobese group (P=0.036). In the propensity-matched cohort, the 5-year survival rates were 54.3% ± 8.9% in the obese group and 81.6% ± 6.8% in the nonobese group (P=0.018). Patients with obesity (BMI, ≥30 kg/m²) who underwent surgery for type A acute aortic dissection had higher operative mortality rates and an increased risk of low cardiac output syndrome, pulmonary complications, and other postoperative morbidities than did patients without obesity. Additional extensive studies are needed to confirm our findings.

Unexpected role of the human cytomegalovirus contribute to essential hypertension in the Kazakh Chinese population of Xinjiang

Human cytomegalovirus (HCMV) infection, chronic inflammation and oxidative stress, the renin-angiotensin system (RAS), endothelial function, and DNA methylation play roles in the pathogenesis of essential hypertension (EH); however, the mechanism by which HCMV predisposes patients to hypertension remain unclear. Our group previously demonstrated an association between EH and HCMV infection in Kazakh Chinese. Here, we investigated the relationship between HCMV infection and other clinicopathological features in 720 Kazakh individuals with or without hypertension (n=360 each; age: 18-80). Multiple linear and logistic regression analyses were used to determine the associations between HCMV infection, clinical characteristics, and EH. Notably, patients with EH, particularly those with HCMV infection, exhibited a marked increase in tumor necrosis factor-α (TNF-α) and 8-hydroxy-2-deoxyguanosine (8-OHDG) levels, but a decrease in endothelial nitric oxide synthase (eNOS) and renin levels. Similarly, elevated TNF-α and 8-OHDG levels were independent predictors of increased HCMV antibody titers, whereas eNOS and renin were negatively correlated with the latter. Moreover, serum angiotensin-converting enzyme (sACE, ACE) methylation was increased, whereas 11-β hydroxysteroid dehydrogenase 2 (HSD11β2; HSD3B2) methylation was decreased in patients with EH who were also infected with HCMV. A positive correlation between HSD3B2 methylation and HCMV IgG titer and blood pressure was additionally observed, whereas angiotensin-converting enzyme (ACE) methylation was inversely correlated with blood pressure. Collectively, these data indicate that HCMV may contribute to EH development in the Kazakh Chinese by increasing TNF-α and 8-OHDG levels, suppressing eNOS and renin, and manipulating HSD3B2 and ACE methylation.

Environmental perturbations lead to extensive directional shifts in RNA processing

Environmental perturbations have large effects on both organismal and cellular traits, including gene expression, but the extent to which the environment affects RNA processing remains largely uncharacterized. Recent studies have identified a large number of genetic variants associated with variation in RNA processing that also have an important role in complex traits; yet we do not know in which contexts the different underlying isoforms are used. Here, we comprehensively characterized changes in RNA processing events across 89 environments in five human cell types and identified 15,300 event shifts (FDR = 15%) comprised of eight event types in over 4,000 genes. Many of these changes occur consistently in the same direction across conditions, indicative of global regulation by trans factors. Accordingly, we demonstrate that environmental modulation of splicing factor binding predicts shifts in intron retention, and that binding of transcription factors predicts shifts in alternative first exon (AFE) usage in response to specific treatments. We validated the mechanism hypothesized for AFE in two independent datasets. Using ATAC-seq, we found altered binding of 64 factors in response to selenium at sites of AFE shift, including ELF2 and other factors in the ETS family. We also performed AFE QTL mapping in 373 individuals and found an enrichment for SNPs predicted to disrupt binding of the ELF2 factor. Together, these results demonstrate that RNA processing is dramatically changed in response to environmental perturbations through specific mechanisms regulated by trans factors.

Synergistic Association of Genetic Variants with Environmental Risk Factors in Susceptibility to Essential Hypertension

AIMS

Essential hypertension (EH) is a disease in which both environment and genes have an important role. This study was designed to identify the interaction model between genetic variants and environmental risk factors that most highly potentiates EH development.

METHODS

We performed a case-control study with 1641 participants (mean age 50.6 ± 8.1 years), specifically 848 patients with EH and 793 controls, adjusted for gender and age. Traditional risk factors, biochemical and genetic parameters, including the genotypic discrimination of 14 genetic variants previously associated with EH, were investigated. Multifactorial dimensionality reduction (MDR) software was used to analyze gene-environment interactions. Validation was performed using logistic regression analysis with environmental risk factors, significant genetic variants, and the best MDR model.

RESULTS

The best model indicates that the interactions among the ADD1 rs4961 640T allele, diabetes, and obesity (body mass index ≥30) increase approximately four-fold the risk of EH (odds ratio = 3.725; 95% confidence interval: 2.945-4.711; p < 0.0001).

CONCLUSION

This work showed that the interaction between the ADD1 rs4961 variant, obesity, and the presence of diabetes increased the susceptibility to EH four-fold. In these circumstances, lifestyle adjustment and diabetes control should be intensified in patients who carry the ADD1 variant.

Association of the Glu504Lys polymorphism in the aldehyde dehydrogenase 2 gene with endothelium-dependent dilation disorder in Chinese Han patients with essential hypertension

BACKGROUND

In essential hypertension (EH), 30-50% of the variability in blood pressure is determined by genetic factors. The aldehyde dehydrogenase 2 (ALDH2) gene Glu504Lys polymorphism is associated with 'alcohol flush' and might be associated with EH.

AIMS

The aim of the present study was to investigate the association of the Glu504Lys polymorphism in the ALDH2 gene with endothelium-dependent dilation (EDD) disorder in Chinese Han patients with EH.

METHODS

This case-control study enrolled 1210 patients with EH. The control group consisted of 1089 healthy subjects with normal blood pressure. Patients with EH were divided into normal brachial arterial flow-mediated dilation (FMD) (EH1 group, n = 354) versus endothelial dysfunction (EH2 group, n = 856). ALDH2 gene Glu504Lys polymorphism was detected using a DNA microarray.

RESULTS

The ALDH2 AA/AG genotypes and the A allele frequencies were significantly higher in the EH group compared with healthy controls (both P < 0.05) and significantly higher in the EH2 group compared with the EH1 group (79.8 vs 51.4%; 45.0 vs 29.1%, respectively; both P < 0.05). Multivariate logistic regression analyses showed that the ALDH2 gene Glu504Lys polymorphism was independently associated with EH (dominant: odds ratio (OR) = 1.38; 95% confidence interval (95% CI) = 1.14-2.82; P = 0.01; additive: OR = 1.32; 95% CI = 1.12-2.44; P = 0.02) as well as with EDD in patients with EH (dominant: OR = 1.49, 95% CI = 1.16-3.01, P = 0.02; additive: OR = 1.43, 95% CI = 1.10-2.87, P = 0.03).

CONCLUSION

The ALDH2 Glu504Lys polymorphism was associated with EDD disorders in Chinese Han patients with EH, providing further evidence that this mutation and 'alcohol flush' are not harmless in this Asian population.

Proteomics and metabolomics in ageing research: from biomarkers to systems biology

Age is the single greatest risk factor for a wide range of diseases, and as the mean age of human populations grows steadily older, the impact of this risk factor grows as well. Laboratory studies on the basic biology of ageing have shed light on numerous genetic pathways that have strong effects on lifespan. However, we still do not know the degree to which the pathways that affect ageing in the lab also influence variation in rates of ageing and age-related disease in human populations. Similarly, despite considerable effort, we have yet to identify reliable and reproducible 'biomarkers', which are predictors of one's biological as opposed to chronological age. One challenge lies in the enormous mechanistic distance between genotype and downstream ageing phenotypes. Here, we consider the power of studying 'endophenotypes' in the context of ageing. Endophenotypes are the various molecular domains that exist at intermediate levels of organization between the genotype and phenotype. We focus our attention specifically on proteins and metabolites. Proteomic and metabolomic profiling has the potential to help identify the underlying causal mechanisms that link genotype to phenotype. We present a brief review of proteomics and metabolomics in ageing research with a focus on the potential of a systems biology and network-centric perspective in geroscience. While network analyses to study ageing utilizing proteomics and metabolomics are in their infancy, they may be the powerful model needed to discover underlying biological processes that influence natural variation in ageing, age-related disease, and longevity.

The importance of gene-environment interactions in human obesity

The worldwide obesity epidemic has been mainly attributed to lifestyle changes. However, who becomes obese in an obesity-prone environment is largely determined by genetic factors. In the last 20 years, important progress has been made in the elucidation of the genetic architecture of obesity. In parallel with successful gene identifications, the number of gene-environment interaction (GEI) studies has grown rapidly. This paper reviews the growing body of evidence supporting gene-environment interactions in the field of obesity. Heritability, monogenic and polygenic obesity studies provide converging evidence that obesity-predisposing genes interact with a variety of environmental, lifestyle and treatment exposures. However, some skepticism remains regarding the validity of these studies based on several issues, which include statistical modelling, confounding, low replication rate, underpowered analyses, biological assumptions and measurement precision. What follows in this review includes (1) an introduction to the study of GEI, (2) the evidence of GEI in the field of obesity, (3) an outline of the biological mechanisms that may explain these interaction effects, (4) methodological challenges associated with GEI studies and potential solutions, and (5) future directions of GEI research. Thus far, this growing body of evidence has provided a deeper understanding of GEI influencing obesity and may have tremendous applications in the emerging field of personalized medicine and individualized lifestyle recommendations.

Leptin Receptor Gene Polymorphism and the Risk of Cardiovascular Disease: A Systemic Review and Meta-Analysis

OBJECTIVE

Few studies have assessed the association between leptin receptor (LEPR) gene polymorphism and the risk of cardiovascular disease (CVD). Of the few epidemiological studies on this topic, the results are still controversial.

METHODS

PubMed and Embase were screened for studies from their inception to 9 October 2016. The pooled odds ratio (OR) with the corresponding confidence intervals (CI) were used to measure the effect size for studies that reported the association under allelic, homozygous, and dominant models. Pre-specified characteristics were conducted in the subgroup analysis. Heterogeneity between subgroups was evaluated by meta-regression analysis.

RESULTS

Seven eligible studies involving 44,133 participants were included in our meta-analysis. Borderline significant association was observed between the LEPR gene polymorphism (rs1137101, rs1137100, rs6700896, and rs8179183) and the increased risk of CVD with considerable heterogeneity under the allelic model, and the overall pooled OR (95% CI) was 1.10 (0.99, 1.22). The LEPR gene variant rs6700896, 109G allele, and 109GG genotype were significantly associated with the increased risk of CVD. Furthermore, stratified group analysis revealed that the association was more pronounced for stroke. Race-differences might also cause the considerable heterogeneity and non-significant association.

CONCLUSIONS

This is the first systematic review and meta-analysis to investigate the association between LEPR gene variants and CVD risk. Some LEPR gene variants were significantly associated with the increased risk of CVD. However, the present study is limited in its small number of included studies, considerable heterogeneity, and observational study design. Further research is still warranted to confirm the magnitude of the association.

Association between Carotid Intima-media Thickness and Aldehyde Dehydrogenase 2 Glu504Lys Polymorphism in Chinese Han with Essential Hypertension

BACKGROUND

Aldehyde dehydrogenase 2 (ALDH2) is involved in the pathophysiological processes of cardiovascular diseases. Recent studies showed that mutant ALDH2 could increase oxidative stress and is a susceptible factor for hypertension. In addition, wild-type ALDH2 could improve the endothelial functions, therefore reducing the risk of developing atherosclerosis. The aim of the present study was to explore the frequency of the Glu504Lys polymorphism of the ALDH2 gene and its relation to carotid intima-media thickness (CIMT) in a group of patients with essential hypertension (EH) and to investigate the association between the Glu504Lys polymorphism and CIMT in Chinese Han patients with EH.

METHODS

In this study, 410 Chinese Han patients with EH who received physical examinations at the People's Hospital of Sichuan Province (China) were selected. DNA microarray chip was used for the genotyping of the Glu504Lys polymorphism of the ALDH2 gene. The differences in CIMT among patients with different Glu504Lys ALDH2 genotypes were analyzed.

RESULTS

The mean CIMT of the patients carrying AA/AG and GG genotypes was 1.02 ± 0.31 mm and 0.78 ± 0.28 mm, respectively. One-way ANOVA showed that the CIMT of the patients carrying the AA/AG genotype was significantly higher than in the ones carrying the GG genotype (P < 0.001). Multivariate logistic regression showed that the Glu504Lys AA/AG genotype of the ALDH2 gene was one of the major factors influencing the CIMT in patients with EH (odds ratio = 3.731, 95% confidence interval = 1.589-8.124, P = 0.001).

CONCLUSIONS

The Glu504Lys polymorphism of the ALDH2 gene is associated with the CIMT of Chinese Han patients with EH in Sichuan, China.

The heritable basis of gene-environment interactions in cardiometabolic traits

AIMS/HYPOTHESIS

Little is known about the heritable basis of gene-environment interactions in humans. We therefore screened multiple cardiometabolic traits to assess the probability that they are influenced by genotype-environment interactions.

METHODS

Fourteen established environmental risk exposures and 11 cardiometabolic traits were analysed in the VIKING study, a cohort of 16,430 Swedish adults from 1682 extended pedigrees with available detailed genealogical, phenotypic and demographic information, using a maximum likelihood variance decomposition method in Sequential Oligogenic Linkage Analysis Routines software.

RESULTS

All cardiometabolic traits had statistically significant heritability estimates, with narrow-sense heritabilities (h ²) ranging from 24% to 47%. Genotype-environment interactions were detected for age and sex (for the majority of traits), physical activity (for triacylglycerols, 2 h glucose and diastolic BP), smoking (for weight), alcohol intake (for weight, BMI and 2 h glucose) and diet pattern (for weight, BMI, glycaemic traits and systolic BP). Genotype-age interactions for weight and systolic BP, genotype-sex interactions for BMI and triacylglycerols and genotype-alcohol intake interactions for weight remained significant after multiple test correction.

CONCLUSIONS/INTERPRETATION

Age, sex and alcohol intake are likely to be major modifiers of genetic effects for a range of cardiometabolic traits. This information may prove valuable for studies that seek to identify specific loci that modify the effects of lifestyle in cardiometabolic disease.

Association between global leukocyte DNA methylation and cardiovascular risk in postmenopausal women

Background

Genetic studies to date have not provided satisfactory evidence regarding risk polymorphisms for cardiovascular disease (CVD). Conversely, epigenetic mechanisms, including DNA methylation, seem to influence the risk of CVD and related conditions. Because postmenopausal women experience an increase in CVD, we set out to determine whether global DNA methylation was associated with cardiovascular risk in this population.

Methods

In this cross sectional study carried out in a university hospital, 90 postmenopausal women without prior CVD diagnosis (55.5 ± 4.9 years, 5.8 [3.0–10.0] years since menopause) were enrolled. DNA was extracted from peripheral leukocytes and global DNA methylation levels were obtained with an ELISA kit. Cardiovascular risk was estimated by the Framingham General Cardiovascular Risk Score (10-year risk) (FRS). Clinical and laboratory variables were assessed. Patients were stratified into two CVD risk groups: low (FRS: <10 %, n = 69) and intermediate/high risk (FRS ≥10 %, n = 21).

Results

Age, time since menopause, blood pressure, total cholesterol, and LDL-c levels were higher in FRS ≥10 % group vs. FRS <10 % group. BMI, triglycerides, HDL-c, HOMA-IR, glucose and hsC-reactive protein levels were similar in the two groups. Global DNA methylation (% 5mC) in the overall sample was 26.5 % (23.6–36.9). The FRS ≥10 % group presented lower global methylation levels compared with the FRS <10 % group: 23.9 % (20.6–29.1) vs. 28.8 % (24.3–39.6), p = 0.02. This analysis remained significant even after adjustment for time since menopause (p = 0.02).

Conclusions

Our results indicate that lower global DNA methylation is associated with higher cardiovascular risk in postmenopausal women.

Coexisting anxiety disorders alter associations with physical disorders in the elderly: A Taiwan cross-sectional nationwide study

AIM

We used population-based analyses to explore whether anxiety disorders are associated with certain physical illnesses, as previous studies have suggested, and whether a greater number of comorbid anxiety disorders would influence physical illnesses in the elderly.

METHODS

Using the National Health Insurance Research Database, we included subjects aged over 60 years. The study included 954 subjects with anxiety disorders (as defined by the ICD-9-CM) and 4770 control subjects without anxiety disorders. Odds ratios (OR) were calculated for the risks of physical illnesses in both groups.

RESULTS

Subjects with anxiety disorders had higher OR for cardiovascular disease (OR = 1.33-2.80), cerebrovascular disease (OR = 2.07), peptic ulcer (OR = 3.41), and hyperlipidemia (OR = 2.99). Furthermore, a greater number of comorbid anxiety disorders may further increase the OR of the aforementioned physical illnesses, except for peripheral vascular disorder, when compared to those without anxiety disorders.

CONCLUSION

Elderly subjects with more anxiety disorders may be associated with vascular and metabolic problems. Clinicians should carefully assess the physical illnesses of elderly patients with anxiety disorders.

Interaction effect of serum 25-hydroxyvitamin D levels and CYP1A1, CYP1B1 polymorphisms on blood pressure in an elderly population

OBJECTIVE

Hypertension and vitamin D deficiency are prevalent worldwide, especially in the elderly. Considering the possibility of gene-environment contributions to disease development, we evaluated the influence of certain cytochrome P450 polymorphisms and vitamin D levels on blood pressure (BP).

METHODS

We measured serum 25-hydroxyvitamin D levels [25(OH)D] and BP in 535 individuals over 60 years old and identified single-nucleotide polymorphisms (SNPs) of CYP1A1 and CYP1B1 in lymphocyte DNA. Repeated measure analyses were used to determine the statistical association.

RESULTS

The relationship between 25(OH)D and SBP or DBP was inversely significant, and influence of several CYP1A1 and CYP1B1 SNPs on BP was found across different genotypes. Estimated effect of 25(OH)D levels on BP in the group with higher risky genotype scores of selected SNPs (rs4646421, rs2551188, and rs1056836) was greater (β = -2.841, P = 0.004 for SBP; β = -2.035, P = 0.001 for DBP) than the group with lower genotype score (β = -0.878, P = 0.347 for SBP; β = 0.037, P = 0.947 for DBP), and synergistic interaction between vitamin D levels and genotype variations was observed (P-interaction = 0.081 for SBP and 0.008 for DBP). When stratified by the hypertension medication status, interaction effect was found only in individuals taking medication (P-interaction = 0.004 for SBP and 0.001 for DBP).

CONCLUSION

Genetic variations in CYP1A1 and CYP1B1 and the serum levels of 25(OH)D showed synergistic effect on BP, especially in individuals currently in treatment for hypertension.

Gender-Specific Association of ATP2B1 Variants with Susceptibility to Essential Hypertension in the Han Chinese Population

Previous genome-wide association studies (GWASs) found that several ATP2B1 variants are associated with essential hypertension (EHT). But the "genome-wide significant" ATP2B1 SNPs (rs2681472, rs2681492, rs17249754, and rs1105378) are in strong linkage disequilibrium (LD) and are located in the same LD block in Chinese populations. We asked whether there are other SNPs within the ATP2B1 gene associated with susceptibility to EHT in the Han Chinese population. Therefore, we performed a case-control study to investigate the association of seven tagSNPs within the ATP2B1 gene and EHT in the Han Chinese population, and we then analyzed the interaction among different SNPs and nongenetic risk factors for EHT. A total of 902 essential hypertensive cases and 902 normotensive controls were involved in the study. All 7 tagSNPs within the ATP2B1 gene were retrieved from HapMap, and genotyping was performed using the Tm-shift genotyping method. Chi-squared test, logistic regression, and propensity score analysis showed that rs17249754 was associated with EHT, particularly in females. The MDR analysis demonstrated that the interaction of rs2070759, rs17249754, TC, TG, and BMI increased the susceptibility to hypertension. Crossover analysis and stratified analysis indicated that BMI has a major effect on the development of hypertension, while ATP2B1 variants have a minor effect.

The relation between the presence of cardiovascular disease and vascular risk factors in offspring and the occurrence of new vascular events in their parents already at high vascular risk

BACKGROUND

For parents at high risk for cardiovascular events, presence of cardiovascular disease or risk factors in their offspring may be an indicator of their genetic load or exposure to (unknown) risk factors and might be related to the development of new or recurrent vascular events.

METHODS

In 4,267 patients with vascular disease, hypertension, diabetes, or hypercholesterolemia enrolled in the SMART cohort, the presence of cardiovascular risk factors (hypertension, diabetes, hypercholesterolemia, smoking, or overweight) and cardiovascular disease (coronary artery disease, cerebrovascular disease, peripheral artery disease, or abdominal aortic aneurysm) was assessed in their 10,564 children. The relation between presence of cardiovascular disease or cardiovascular risk factors in their offspring and new or recurrent vascular events was determined by Cox proportional hazard analyses.

RESULTS

Of the patients, 506 (12%) had offspring with cardiovascular disease, hypertension, hypercholesterolemia, or diabetes. Smoking in offspring was present in 1,972 patients (46%), and overweight in 845 patients (20%). During a median follow-up of 7.0 years (interquartile range 3.7-10.4), the composite outcome of myocardial infarction (MI), stroke, or vascular mortality occurred in 251 patients. Patients with offspring with cardiovascular disease, hypertension, hypercholesterolemia, or diabetes had an increased risk of vascular mortality (hazard ratio [HR] 2.9, 95% CI 1.2-7.1), MI (HR 1.6, 95% CI 1.1-2.5), and the composite outcome (HR 1.5, 95% CI 1.1-2.2). Diabetes in offspring was related to an increased risk of the composite outcome (HR 2.7, 95% CI 1.5-5.0), MI (HR 3.3, 95% CI 1.7-6.6), and vascular mortality (HR 3.4, 95% CI 0.8-14.8). Smoking and overweight in offspring were not related to increased vascular risk in parents.

CONCLUSIONS

Presence of cardiovascular disease, hypertension, hypercholesterolemia, and diabetes in offspring, with diabetes mellitus being the most contributing cardiovascular risk factor, is related to an increased risk of developing new or subsequent vascular events in patients already at high vascular risk.

Is the association of hypertension with cardiovascular events stronger among the lean and normal weight than among the overweight and obese? The multi-ethnic study of atherosclerosis

Previous studies that suggest the association of hypertension with cardiovascular disease (CVD) events is stronger in the lean/normal weight than in the obese have either included smokers, diabetics, or cancer patients, or did not account for central obesity. This study examines the interaction of adiposity with hypertension on CVD events using body mass index (BMI)-based definitions of overweight and obesity, as well as waist circumference (WC) to assess adiposity. In the Multi-Ethnic Study of Atherosclerosis, we classified 3657 nonsmoking men and women, free of baseline clinical CVD, diabetes mellitus and cancer, into 7 BMI-WC combinations defined by ethnicity-specific BMI (normal, overweight, class 1 obese, and class 2/3 obese) and ethnicity- and sex-specific WC categories (optimal or nonoptimal). Adjusted absolute event rates per 1000 person-years and relative risks (95% confidence intervals) for CVD events for hypertension (blood pressure ≥140/90 or taking medication) versus no hypertension computed within adiposity categories were 9.3 versus 1.9 and 4.96 (2.56-9.60) for normal BMI/optimal WC, 13.2 versus 4.2 and 3.13 (0.99-9.86) for normal BMI/nonoptimal WC, 9.0 versus 4.5 and 2.00 (1.19-3.36) for overweight BMI/optimal WC, 8.4 versus 5.6 and 1.50 (0.88-2.54) for overweight BMI/nonoptimal WC,14.1 versus 2.1 and 6.75 (0.69-65.57) for class 1 obese/optimal WC, 10.1 versus 3.7 and 2.69 (1.41-5.16) for class 1 obese/nonoptimal WC, and 9.9 versus 6.9 and 1.45(0.60-3.52) for class 2/3 obese/WC pooled. This study found a large relative risk of CVD events associated with hypertension for normal BMI participants and more importantly similarly high absolute risks for both normal and obese BMI with hypertension.

Gene-environment interaction in dyslipidemia

PURPOSE OF REVIEW

Recent genome-wide association studies have identified numerous common genetic variants associated with plasma lipid traits and have provided new insights into the regulation of lipoprotein metabolism including the identification of novel biological processes. These findings add to a body of existing data on dietary and environmental factors affecting plasma lipids. Here we explore how interactions between genetic risk factors and other phenotypes may explain some of the missing heritability of plasma lipid traits.

RECENT FINDINGS

Recent studies have identified true statistical interaction between several environmental and genetic risk factors and their effects on plasma lipid fractions. These include interactions between behaviors such as smoking or exercise as well as specific dietary nutrients and the effect size of specific genetic variants on plasma lipid traits risk and modifying effects of measures of adiposity on the cumulative impact of a number of common genetic variants on each of plasma triglycerides and HDL cholesterol.

SUMMARY

Interactions between genetic risk factors and clinical phenotypes may account for some of the unexplained heritability of plasma lipid traits. Recent studies provide biological insight into specific genetic associations and may aid in the identification of dyslipidemic patients for whom specific lifestyle interventions are likely to be most effective.

Gene-gene and gene-environment interactions detected by transcriptome sequence analysis in twins

Understanding the genetic architecture of gene expression is an intermediate step in understanding the genetic architecture of complex diseases. RNA sequencing technologies have improved the quantification of gene expression and allow measurement of allele-specific expression (ASE). ASE is hypothesized to result from the direct effect of cis regulatory variants, but a proper estimation of the causes of ASE has not been performed thus far. In this study, we take advantage of a sample of twins to measure the relative contributions of genetic and environmental effects to ASE, and we find substantial effects from gene × gene (G×G) and gene × environment (G×E) interactions. We propose a model where ASE requires genetic variability in cis, a difference in the sequence of both alleles, but where the magnitude of the ASE effect depends on trans genetic and environmental factors that interact with the cis genetic variants.

Omega-3 fatty acids and the genetic risk of early onset acute coronary syndrome

BACKGROUND AND AIMS

Recent gene-environment interaction studies suggest that diet may influence an individual's genetic predisposition to cardiovascular risk. We evaluated whether omega-3 fatty acid intake may influence the risk for acute coronary syndrome (ACS) conferred by genetic polymorphisms among patients with early onset ACS.

METHODS AND RESULTS

Our population consisted of 705 patients of white European descent enrolled in GENESIS-PRAXY, a multicenter cohort study of patients aged 18-55 years and hospitalized with ACS. We used a case-only design to investigate interactions between the omega-3 index (a validated biomarker of omega-3 fatty acid intake) and 30 single nucleotide polymorphisms (SNPs) robustly associated with ACS. We used logistic regression to assess the interaction between each SNP and the omega-3 index. Interaction was also assessed between the omega-3 index and a genetic risk score generated from the 30 SNPs. All models were adjusted for age and sex. An interaction for increased ACS risk was found between carriers of the chromosome 9p21 variant rs4977574 and low omega-3 index (OR 1.57, 95% CI 1.07-2.32, p = 0.02), but this was not significant after correction for multiple testing. Similar results were obtained in the adjusted model (OR 1.55, 95% CI 1.05-2.29, p = 0.03). We did not observe any interaction between the genetic risk score or any of the other SNPs and the omega-3 index.

CONCLUSION

Our results suggest that omega-3 fatty acid intake may modify the genetic risk conferred by chromosome 9p21 variation in the development of early onset ACS and requires independent replication.

Exploring unknowns in cardiology

To mark the 10th anniversary of Nature Reviews Cardiology in November 2014, five of our Advisory Board members were invited to consider a topic within cardiology about which we know too little. A diverse range of subjects are highlighted in this Perspectives article, including preoperative assessment of right ventricular function, the burden of cardiomyopathies in Africa, the measurement of fractional flow reserve to guide coronary intervention, the interaction between genes and environment in cardiovascular disease, and the difficulty of predicting atherosclerotic plaque rupture. The five key opinion leaders from around the globe also suggest ways in which future research could be targeted to address the deficits in our understanding, with the aim of preventing cardiovascular disease, improving patient care, and reducing morbidity and mortality.

Effects of living at higher altitudes on mortality: a narrative review

Beside genetic and life-style characteristics environmental factors may profoundly influence mortality and life expectancy. The high altitude climate comprises a set of conditions bearing the potential of modifying morbidity and mortality of approximately 400 million people who are permanently residing at elevations above 1500 meters. However, epidemiological data on the effects of high altitude living on mortality from major diseases are inconsistent probably due to differences in ethnicity, behavioral factors and the complex interactions with environmental conditions. The available data indicate that residency at higher altitudes are associated with lower mortality from cardiovascular diseases, stroke and certain types of cancer. In contrast mortality from COPD and probably also from lower respiratory tract infections is rather elevated. It may be argued that moderate altitudes are more protective than high or even very high altitudes. Whereas living at higher elevations may frequently protect from development of diseases, it could adversely affect mortality when diseases progress. Corroborating and expanding these findings would be helpful for optimization of medical care and disease management in the aging residents of higher altitudes.

Body mass index, cardiac surgery and clinical outcome. A single-center experience with 9125 patients

BACKGROUND AND AIM

There is evidence for a J-shaped association between Body Mass Index (BMI) and all-cause mortality in general populations. In cardiac surgical patients, the effect of BMI on mortality and major adverse cardiac and cerebrovascular events (MACCE) is not completely clear.

METHODS AND RESULTS

We investigated the effect of BMI on MACCE (primary endpoint), as well as intensive care unit (ICU)-related outcomes and mid-term mortality in 9125 consecutive patients who were operated on at our institution between July 2009 and July 2012. Of the study cohort, 3.0% were underweight (BMI < 20 kg/m(2)), 28.0% had a normal BMI (20-24.99 kg/m(2)), 43.1% were overweight (BMI 25-29.99 kg/m(2)), 19.3% were obese (BMI 30-34.99 kg/m(2)), and 6.6% were severely obese (BMI ≥ 35 kg/m(2)). Compared with overweight patients (lowest incidence of MACCE), the multivariable-adjusted odds ratio of MACCE in severely obese patients was 1.39 (95% CI: 1.03-1.87). Underweight and severely obese patients had the longest risk-adjusted duration of mechanical ventilator support and ICU stay (P-values 0.004-0.001). The red blood cell concentrates requirement was highest in underweight patients (P < 0.001). Compared with normal and overweight patients, the multivariable-adjusted hazard ratio of 2-year mortality was higher in underweight patients (1.72 [95% CI: 1.26-2.36] and =2.07 [95% CI: 1.51-2.83], respectively), but did not differ significantly in severely obese patients.

CONCLUSION

Data demonstrate that both severe obesity and underweight are independent risk factors for operative complications in cardiac surgical patients. With respect to mid-term survival, special attention should be paid to underweight patients scheduled for cardiac surgery.

Joint effects of mitochondrial DNA 5178 C/A polymorphism and coffee consumption or alcohol consumption on clustering of cardiovascular risk factors in middle-aged Japanese men: a cross-sectional study

Background

Longevity-associated mitochondrial DNA 5178 (Mt5178) C/A reportedly modulates the effects of coffee consumption on the risk of hypertension, dyslipidemia and abnormal glucose tolerance, and those of alcohol consumption on the risk of hypertension, dyslipidemia and hyperuricemia in middle-aged Japanese men. However, there has been no research examining whether Mt5178 C/A polymorphism influences the effects of coffee consumption or alcohol consumption on the clustering of cardiovascular risk factors (CRFs).

Methods

A total of 332 male subjects (mean age ± SD, 52.8 ± 7.8 years) were selected from among individuals visiting the hospital for regular medical check-ups. After Mt5178 C/A genotyping, a cross-sectional study assessing the joint effects of Mt5178 C/A polymorphism and coffee consumption or alcohol consumption on the clustering of CRFs, namely hypertension, abnormal glucose tolerance, hyper-low-density lipoprotein cholesterolemia, hypo-high density lipoprotein cholesterolemia, hypertriglyceridemia and hyperuricemia, was then conducted.

Results

After adjustment for confounding factors, significant and negative associations were observed between coffee consumption and clustering of ≥2 CRFs in subjects with Mt5178C. The adjusted odds ratio (OR) for the clustering of ≥2 or ≥3 CRFs was significantly lower in subjects who consumed 1–3 cups of coffee per day than in those who consumed <1 cup of coffee per day (OR = 0.496, 95% confidence interval (CI): 0.249–0.989, and OR = 0.369, 95% CI: 0.165–0.826, respectively). On the other hand, after adjustment, positive associations between coffee consumption and clustering of ≥2 CRFs were observed in subjects with Mt5178A. However, these associations did not reach a significant level. For Mt5178C genotypic men, the adjusted OR for the clustering of ≥2 or ≥3 CRFs was significantly higher in daily drinkers than in occasional drinkers (OR = 2.737, 95% CI: 1.361–5.502, and OR = 3.024, 95% CI: 1.269–7.210, respectively). On the other hand, the association between Mt5178A genotype and the clustering of ≥2 or ≥3 CRFs did not appear to depend on alcohol consumption.

Conclusions

The present results suggest that Mt5178 C/A polymorphism modifies the effects of coffee consumption or alcohol consumption on the clustering of CRFs in middle-aged Japanese men.

Association between polymorphisms in the renin-angiotensin-aldosterone system genes and essential hypertension in the Han Chinese population

BACKGROUND

Renin-angiotensin-aldosterone system (RAAS) is the most important endocrine blood pressure control mechanism in our body, genes encoding components of this system have been strong candidates for the investigation of the genetic basis of hypertension. However, previous studies mainly focused on limited polymorphisms, thus we carried out a case-control study in the Han Chinese population to systemically investigate the association between polymorphisms in the RAAS genes and essential hypertension.

METHODS

905 essential hypertensive cases and 905 normotensive controls were recruited based on stringent inclusion and exclusion criteria. All 41 tagSNPs within RAAS genes were retrieved from HapMap, and the genotyping was performed using the GenomeLab SNPstream Genotyping System. Logistic regression analysis, Multifactor dimensionality reduction (MDR), stratified analysis and crossover analysis were used to identify and characterize interactions among the SNPs and the non-genetic factors.

RESULTS

Serum levels of total cholesterol (TC) and triglyceride (TG), and body mass index (BMI) were significantly higher in the hypertensive group than in the control group. Of 41 SNPs genotyped, rs3789678 and rs2493132 within AGT, rs4305 within ACE, rs275645 within AGTR1, rs3802230 and rs10086846 within CYP11B2 were shown to associate with hypertension. The MDR analysis demonstrated that the interaction between BMI and rs4305 increased the susceptibility to hypertension. Crossover analysis and stratified analysis further indicated that BMI has a major effect, and rs4305 has a minor effect.

CONCLUSION

These novel findings indicated that together with non-genetic factors, these genetic variants in the RAAS may play an important role in determining an individual's susceptibility to hypertension in the Han Chinese.