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

Genetic Appraisal of RAAS-Associated SNPs: REN (rs16853055), AGT (rs3789678) and ACE (rs4305) in Preeclamptic Women Living with HIV Infection

PURPOSE OF REVIEW

The primary goal of this review article was to determine whether the three RAAS-associated SNPs, Renin-rs16853055, AGT-rs3789678 and ACE-rs4305 are genetically linked to the development of hypertension in preeclampsia. The secondary goal was to establish if there was a link between these SNPs and HIV infection.

RECENT FINDINGS

There is a paucity of findings related to the aforementioned SNPs and preeclampsia. There are no recent findings on the rs16853055 renin polymorphism. The rs3789678 angiotensinogen polymorphism correlated significantly with gestational hypertension. The rs4305 ACE polymorphism showed no significant association with the development of pregnancy-induced hypertension. There are conflicting findings when determining the relationship between ethnicity and the predisposition of preeclampsia and hypertension in relation to the discussed RAAS-associated SNPs. To date, the association between RAAS-associated SNPs and preeclamptic women co-morbid with HIV in South Africa has revealed that certain alleles of the AGT gene are more prominent in HIV-infected PE compared to normotensive pregnant HIV-infected women.

No Association Between AGT Gene Polymorphisms with Hypertension in a South African Population

Purpose

Hypertension is a leading cause of cardiovascular-related morbidity and mortality worldwide, with a prevalence increasing at an alarming rate in both middle- and low-income countries. Various environmental and genetic factors have been attributed to play a significant role in the increasing prevalence of hypertension. Single nucleotide polymorphisms (SNPs) in the angiotensinogen (AGT) gene are reported to have a significant association with hypertension; however, there are limited studies done on South African populations. Therefore, this case-control study aimed to investigate the association between AGT SNPs (rs2004776, rs3789678, rs5051 and rs7079) with hypertension in a study population of isiXhosa-speaking participants from the Eastern Cape Province in South Africa.

Materials and Methods

The SNPs were genotyped in 250 hypertensive cases and 237 normotensive controls, using TaqMan genotyping assays.

Results

For the SNP rs2004776, the frequency of CC genotype (18.4%) and C allele (44%) in hypertensive cases showed no significant differences (p = 0.52, χ2 = 1.32), when compared to the normotensive control group (CC: 19.8% and C allele: 43%). Similar results were obtained for the genotypic and allelic frequencies between hypertensive cases and normotensive controls for rs3789678 (p = 0.88, χ2=0.26) and rs5051 (p = 0.57, χ2=1.12), and rs7079 (p = 0.33, χ2=2.23). These findings demonstrate that there were no significant associations between the SNPs rs2004776, rs3789678, rs7079, rs5051 with hypertension in our study population.

Conclusion

These findings suggest that AGT gene polymorphisms are not associated with the development of hypertension in the studied population. The present study represents the first genetic report to investigate the AGT gene polymorphisms with hypertension in an isiXhosa-speaking South African population.

Genetic diet interactions of ACE: the increased hypertension predisposition in the Latin American population

Hypertension is one of the primary risk factors associated with cardiovascular diseases (CVDs). It is a condition that affects people worldwide, and its prevalence is increasing due to several factors, such as lack of physical activity, population aging, and unhealthy diets. Notably, this increase has primarily occurred in low and middle-income countries (LMICs). In Latin America, approximately 40% of adults have been diagnosed with hypertension. Moreover, reports have shown that the Latin American genetic composition is highly diverse, and this genetic background can influence various biological processes, including disease predisposition and treatment effectiveness. Research has shown that Western dietary patterns, which include increased consumption of red meat, refined grains, sugar, and ultra-processed food, have spread across the globe, including Latin America, due to globalization processes. Furthermore, a higher than recommended sodium consumption, which has been associated with hypertension, has been identified across different regions, including Asia, Europe, America, Oceania, and Africa. In conclusion, hypertension is a multifactorial disease involving environmental and genetic factors. In Latin America, hypertension prevalence is increasing due to various factors, including age, the adoption of a "Westernized" diet, and potential genetic predisposition factors involving the ACE gene. Furthermore, identifying the genetic and molecular mechanisms of the disease, its association with diet, and how they interact is essential for the development of personalized treatments to increase its efficacy and reduce side effects.

ADD1 Single Nucleotide Polymorphisms Are Associated With Essential Hypertension Among Han and Mongolian Population in Inner Mongolia Area

Aldosterone synthase (CYP11B2) and α-adducing (ADD1) are candidate genes that play key roles during essential hypertension (EH) incidence. However, the association between their genetic mutations and the risk of EH is unclear. The present study investigated specific single nucleotide polymorphisms (SNPs) from CYP11B2 and ADD1, and their potential role as risk factors for EH based on 423 Mongolian and 410 Han people in Inner Mongolia province. In the allelic model, people with ADD1 rs2239728-A presented a 0.74-fold risk than rs2239728-C, whereas the ADD1 rs4961-T was associated with a 1.37-fold higher risk than allele G in the Han population. The genetic model reported that the rs2239728-A carrier (AA + AC) was 0.59-fold lower than the CC carrier, whereas the rs4961-G carrier (GG + GT) was 0.59-fold lower than the TT carrier in the dominant model. After gender adjustment, people with rs2239728-A was a 0.63-fold risk than –C in EH, but the rs4961-T carrier was associated with a 1.63-times higher risk than –G in females. Haplotype analysis showed that GCCT was associated with essential hypertension in the Han population, and it was a risk factor for EH. Our identification reported novel SNPs of ADD1 with protective significance for EH among females in the Chinese Han population, together with its haplotype GCCT as a risk factor for EH.

Effects of DNA methylation on cardiometabolic risk factors: a systematic review and meta-analysis

Background

Epigenetic changes, especially DNA methylation have a main role in regulating cardiometabolic disorders and their risk factors. This study provides a review of the current evidence on the association between methylation of some genes (LINE1, ABCG1, SREBF1, PHOSPHO1, ADRB3, and LEP) and cardiometabolic risk factors.

Methods

A systematic literature search was conducted in electronic databases including Web of Science, PubMed, EMBASE, Google Scholar and Scopus up to end of 2020. All observational human studies (cross-sectional, case–control, and cohort) were included. Studies that assessed the effect of DNA methylation on cardiometabolic risk factors were selected.

Results

Among 1398 articles, eight studies and twenty-one studies were included in the meta-analysis and the systematic review, respectively. Our study showed ABCG1 and LINE1 methylation were positively associated with blood pressure (Fisher’s zr = 0.07 (0.06, 0.09), 95% CI: 0.05 to 0.08). Methylation in LINE1, ABCG1, SREBF1, PHOSPHO1 and ADRB3 had no significant association with HDL levels (Fisher’s zr = − 0.05 (− 0.13, 0.03), 95% CI:-0.12 to 0.02). Positive association was existed between LINE1, ABCG1 and LEP methylation and LDL levels (Fisher’s zr = 0.13 (0.04, 0.23), 95% CI: 0.03 to 0.23). Moreover, positive association was found between HbA1C and ABCG1 methylation (Fisher’s zr = 0.11 (0.09, 0.13), 95% CI: 0.09 to 0.12). DNA methylation of LINE1, ABCG1 and SREBF1 genes had no significant association with glucose levels (Fisher’s zr = 0.01 (− 0.12, 0.14), 95% CI:-0.12 to 0.14).

Conclusion

This meta-analysis showed that DNA methylation was associated with some cardiometabolic risk factors including LDL-C, HbA1C, and blood pressure.

Registration

Registration ID of the protocol on PROSPERO is CRD42020207677.

Association of the angiotensin I converting enzyme (ACE) gene polymorphisms with recurrent aphthous stomatitis in the Czech population: case–control study

Background

Recurrent aphthous stomatitis (RAS) is multifactorial disease with unclear etiopathogenesis. The aim of this study was to determine distribution of the angiotensin I converting enzyme (ACE) gene polymorphisms and their influence on RAS susceptibility in Czech population.

Methods

The study included 230 subjects (143 healthy controls and 87 patients with RAS) with anamnestic, clinical and laboratory data. Five ACE gene polymorphisms (rs4291/rs4305/rs4311/rs4331/rs1799752 = ACE I/D) were determined by TaqMan technique.

Results

The allele and genotype distributions of the studied ACE I/D polymorphisms were not significantly different between subjects with/without RAS (P_corr > 0.05). However, carriers of II genotype were less frequent in the RAS group (OR = 0.48, 95% CI = 0.21–1.12, P = 0.059). Stratified analysis by sex demonstrated lower frequency of II genotype in women (OR = 0.33, 95% CI = 0.09–1.17, P < 0.035, P_corr > 0.05, respectively) than in men with RAS (P > 0.05). Moreover, the frequency of AGTGD haplotype was significantly increased in RAS patients (OR = 13.74, 95% CI = 1.70–110.79, P = 0.0012, P_corr < 0.05). In subanalysis, TGD haplotype was significantly more frequent in RAS patients (P < 0.00001) and CGI haplotype was less frequent in RAS patients (P < 0.01), especially in women (P = 0.016, P_corr > 0.05).

Conclusions

Our study indicates that while the AGTGD and TGD haplotypes are associated with increased risk of RAS development, CGI haplotype might be one of protective factors against RAS susceptibility in Czech population.

Association between polymorphisms of genes involved in the Renin-Angiotensin-Aldosterone System and the adaptive morphological and functional responses to essential hypertension

Hypertensive cardiac remodeling is illustrated by increased left ventricular (LV) mass index values and/or relative wall thickness (RWT) values >0.42, and functionally by isolated alteration of LV diastole (abnormal relaxation). The aim of the present study was to establish differentiated models of anatomical and functional adaptation to essential hypertension (EHT), in relation to the genetic variants of genes involved in the Renin-Angiotensin-Aldosterone System (RAAS). The M235T-AGT, I/D-ACE, A1166C-R1AngII, A3123C-R2AngII and G83A-REN genotypes were determined using PCR-Restriction Fragment Length Polymorphism in 139 hypertensive subjects. The relationship between the studied RAAS gene polymorphisms with morphological and functional cardiac remodeling was assessed by multiple logistic regression analysis. Patients carrying the C/C, A/C genotypes (A3123C-R2AngII polymorphism) had a 2.72-fold (P=0.033) increased risk of exhibiting an RWT value <0.42; in the multivariate model the risk was 4.02-fold higher (P=0.008). Analysis of LV diastolic dysfunction (LVDD) revealed that hypertensive patients carrying the T/T, M/T genotypes (M235T-AGT polymorphism) had a 2.24-fold (P=0.037) increased risk of developing LVDD and a 2.42-fold increased risk (P=0.039) after adjustment for confounders. Similarly, carriers of the G/G, A/G genotypes (G83A-REN) had a 2.32-fold (P=0.021) increased risk of developing LVDD, and this remained an independent risk factor based on the multivariate model (P=0.033). The results of the present study showed that no particular gene was associated with increased LV mass, but the A3123C-R2AngII polymorphism was associated with a non-concentric type of cardiac response in hypertensive patients. Conversely, the M235T-AGT and G83A-REN polymorphisms were found to be statistically significantly associated with LVDD when assessing abnormal relaxation.

Relationship between AGT rs2493132 polymorphism and the risk of coronary artery disease in patients with NAFLD in the Chinese Han population

Objective

To investigate the relationship between angiotensin (AGT) rs2493132 gene polymorphism and the risk of developing non-alcoholic fatty liver disease (NAFLD) and coronary artery disease (CAD) in the Chinese Han population.

Methods

Polymerase chain reaction was performed to determine AGT genotypes. Anthropometric and clinical data were investigated and statistically analyzed in the clinical laboratory department of Qingdao Municipal Hospital.

Results

The AGT rs2493132 CT + TT genotype was an important risk factor for CAD in patients with NAFLD and NAFLD + CAD in healthy controls. The AGT rs2493132 T allele increased the risk of NAFLD + CAD in healthy controls. The AGT rs2493132 CT + TT genotype and T allele also significantly increased the risk of CAD in patients with NAFLD after adjustments for age, sex, and body mass index. In addition, AGT rs2493132 T allele carriers showed higher total cholesterol (TC) and low-density lipoprotein (LDL) levels compared with non-carriers.

Conclusions

The AGT rs2493132 CT + TT genotype and T allele significantly increased the risk of developing CAD in patients with NAFLD in the Chinese Han population. The AGT rs2493132 T allele was associated with increased serum TC and LDL levels.

The Role of the Renin-Angiotensin-Aldosterone System in Preeclampsia: a Review

PURPOSE OF REVIEW

Preeclampsia (PE) is a complex human pregnancy-specific condition and is clinically characterized by new onset hypertension and proteinuria in the second half of pregnancy. The precise etiology of PE is unknown, but much of the pathophysiology has been elucidated, and it is accepted that the disorder is multifactorial in nature. Historically, because of the presence of proteinuria, the role of the renin-angiotensin-aldosterone system (RAAS) has been considered in the etiology of PE. However, the results of studies (including maternal circulatory angiotensin II, urinary angiotensinogen, plasma renin and prorenin, AT1 receptor antibodies, and gene polymorphisms) on the role of the RAAS in the etiology of PE have proved controversial. The purpose of this narrative review was to evaluate the contemporary literature on the RAAS and its role in the pathophysiology of pregnancy.

RECENT FINDINGS

The current review shows that although the RAAS has a role in the development of normal pregnancy, it does not have a significant role in the pathophysiology of PE except for the AT1-AA components. Despite many researchers having measured increases in s[P}RR and [P]RR, this may be independent of the RAAS. Our view is in keeping with contemporary thinking that the placenta rather than the RAAS plays a central role in elaborating pro-inflammatory factors (antiangiogenic and angiogenic) into the maternal circulation resulting in widespread endothelial dysfunction in all organ systems including the renal system.

Impact on Longevity of Genetic Cardiovascular Risk and Lifestyle including Red Meat Consumption

Background

Cardiovascular risk (CVR) underlies aging process and longevity. Previous work points to genetic and environmental factors associated with this risk.

Objectives

The aim of this research is to look for any CVR gene-gene and gene-multifactorial/lifestyle interactions that may impact health and disease and underlie exceptional longevity.

Methods

A case-control study involving 521 both gender individuals, 253 centenarians (100.26 ± 1.98 years), and 268 controls (67.51 ± 3.25 years), low (LCR, n = 107) and high (HCR, n = 161) CVR. Hypertension, diabetes, obesity (BMI, kg·m⁻²), and impaired kidney function were defined according to standard criteria. CVR was calculated using Q risk®. DNA was genotyping (ACE-rs4646994, AGT-rs4762, AGR1-rs5182, GRK4-rs2960306, GRK4-rs1024323, NOS3-rs1799983, and SLC12A3-rs13306673) through iPlex-MassARRAY®, read by MALDI-TOF mass spectrometry, and analyzed by EARTDECODE®.

Results

Antilongevity factors consisted (OR 95% CI, p < 0.05) BMI 1.558 (1.445-1.680), hypertension 2.358 (1.565-3.553), smoking habits 4.528 (2.579-7.949), diabetes 5.553 (2.889-10.675), hypercholesterolemia 1.016 (1.010-1.022), and regular consumption of red meat 22.363 (13.987-35.755). Genetic aspects particularly for HCR individuals ACE II (OR: 3.96 (1.83-8.56), p < 0.0001) and NOS3 TT (OR: 3.11 (1.70-5.70), p < 0.0001) genotypes were also risk associate. Obesity, smoking, hypercholesterolemia, and frequent consumption of red meat have an additive action to hypertension in the longevity process. There was a synergistic interaction between the endothelial NOS3 genotypes and the severity of arterial hypertension. An epistatic interaction between functional genetic variants of GRK4 and angiotensinogen was also observed.

Conclusions

Cardiovascular risk-related genetic and multifactorial or predominantly lifestyle aspects and its interactions might influence the aging process and contribute to exceptional longevity in Portuguese centenarians. Besides lifestyle, the activity of nitrite oxide synthase may be one of the main physiologic regulators of cardiovascular protection in the path of longevity.

Contribution of Four Polymorphisms in Renin-Angiotensin-Aldosterone-Related Genes to Hypertension in a Thai Population

Introduction

The roles of genes in the renin-angiotensin-aldosterone system (RAAS) in hypertension, including angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II receptor type 1 (AGTR1), and aldosterone synthase (CYP11B2), have been widely studied across different ethnicities, but there has been no such investigation in Thai population.

Materials and Methods

Using 4,150 Thais recorded in the Electricity Generating Authority of Thailand (EGAT) study, we examined the association of rs1799752, rs699, rs5186, and rs1799998 located in or near ACE, AGT, AGTR1, and CYP11B2 genes in hypertension. We investigated their roles in hypertension using multivariate logistic regression and further examined their roles in blood pressure (BP) using quantile regression. Sex, age, and BMI were adjusted as potential confounders.

Results

We did not observe associations between hypertension and rs1799752 (P=0.422), rs699 (P=0.36), rs5186 (P=0.49), and rs1799998 (P=0.71). No evidence of association between these SNPs and BP was found across an entire distribution. A nonlinear relationship between age and BP was observed.

Conclusion

In Thai population, our study showed no evidence of association between RAAS-related genes and hypertension. While our study is the first and largest study to investigate the role of RAAS-related genes in hypertension in Thai population, restricted statistical power due to limited sample size is a limitation.

Unravelling the Lesser Known Facets of Angiotensin II Type 1 Receptor

PURPOSE OF REVIEW

Hypertension is an important risk factor in various pathologies. Despite enormous advancements in health sciences, the number of hypertensive individuals is increasing worldwide. The complex interplay between genetic and epigenetic factors seems to be a promising pathway to exploring the pathophysiology of hypertension.

RECENT FINDINGS

Various single gene and genome wide association studies have generated huge but non-reproducible data that highlights the role of some additional but as yet unidentified factor(s) in disease outcome. Dietary pattern and epigenetic mechanism (mainly DNA methylation) have shown a profound effect on blood pressure regulation. Angiotensin II and its receptors are known to play an important role in maintaining blood pressure; hence, a larger section of antihypertensive drugs targets the renin-angiotensin system (RAS). Angiotensin II type 1 receptor (AT1R), besides maintaining blood pressure, also has a role in cancer progression. Besides other pathways, RAS still remains the main player in blood pressure regulation. Additionally, AT1R has recently emerged as a molecule with diverse roles ranging from physiologic to cancer progression.

Interactions Between PPARG and AGTR1 Gene Polymorphisms on the Risk of Hypertension in Chinese Han Population

AIMS

To explore the interactions between PPARG and AGTR1 polymorphisms and their associations with hypertension in the Chinese Han population.

METHODS

Seven single nucleotide polymorphisms (SNPs) of the PPARG gene and five SNPs of the AGTR1 gene were selected and genotyped in 1591 unrelated Chinese Han adults. The SNPAssoc package of R was used to analyze the associations between the selected SNPs and hypertension. The potential gene-gene interactions between PPARG and AGTR1 genes were tested by model-based multifactor dimensionality reduction (MB-MDR).

RESULTS

The frequencies of the C allele of rs3856806 and the G allele of rs13433696 in the PPARG gene were significantly lower in hypertensive subjects, whereas the A allele of rs9817428 in the PPARG gene was much higher in hypertensives. In addition, individuals with T allele of rs2933249 in the AGTR1 gene displayed a significantly decreased risk of hypertension. MB-MDR analyses suggested that the two-locus model (rs9817428 and rs2933249) and the three-locus model (rs9817428, rs3856806, and rs2933249) were significantly associated with a decreased risk of hypertension. Moreover, among the eight SNPs not individually associated with hypertension (rs12631819, rs2920502, rs1175543, and rs2972164 in the PPARG gene, and rs2638360, rs1492100, rs5182, and rs275646 in the AGTR1 gene), the two-locus model involving rs12631819 and rs5182 demonstrated increased susceptibility to hypertension, and the five-locus model involving rs12631819, rs2920502, rs2972164, rs5182, and rs2638360 demonstrated a significantly decreased risk of hypertension.

CONCLUSION

Polymorphisms in both the PPARG and AGTR1 genes were found to be significantly associated with hypertension. Moreover, there were significant gene-gene interactions identified between the PPARG and AGTR1 genes in relation to hypertension susceptibility in the Chinese Han population.

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.

Renin-angiotensin-aldosterone system gene polymorphisms in gestational hypertension and preeclampsia: A case-control gene-association study

Pregnancy-induced hypertension (PIH, including preeclampsia [PE] and gestational hypertension [GH]) and cardiovascular diseases (CVDs) have some metabolic changes and risk factors in common. Many studies have reported associations between single nucleotide polymorphisms (SNPs) of renin-angiotensin-aldosterone system (RAAS) genes and CVDs (particularly hypertension), and their findings have provided candidate SNPs for research on genetic correlates of PIH. We explored the association between hypertension-related RAAS SNPs and PIH in a Chinese population. A total of 130 cases with PE, 67 cases with GH, and 316 controls were recruited. Six candidate SNPs of the RAAS system were selected. Multiple logistic regression analysis adjusting for maternal age, fetal sex, and gestational diabetes mellitus showed significant associations between angiotensinogen (AGT) rs3789678 T/C and GH (p = 0.0088) and between angiotensin II receptor type 1 (AGTR1) rs275645 G/A and PE (p = 0.0082). The study population was further stratified by maternal age (<30 and ≥30 years), and stratified and crossover analyses were conducted to determine genetic associations in different age groups. Our findings suggest that the impacts of different SNPs might be affected by maternal age; however, the effect of this potential gene-age interaction on PIH needs further exploration.

Madagascine Induces Vasodilatation via Activation of AMPK

Madagascine (3-isopentenyloxyemodin) can be chemically synthesized or purified from several Rhamnus species, and it is found to have more potent biological activities than the parent compound emodin. The aim of this study is to characterize the vasodilatory effect of madagascine on vasoconstriction and sphingosylphosphorylcholine induced vasospasm in ex vivo and reveal the potential mechanisms in vitro. The effects of madagascine on vasoconstriction of rat mesenteric resistance arteries (MRAs) induced by K⁺, methoxamine, and endothelin-1 were, respectively, studied. The cholesterol-enriched porcine coronary vascular smooth muscle (VSM) strips were used to investigate the effects of madagascine on abnormal constriction induced by sphingosylphosphorylcholine (SPC) which has a pivotal role in vasospasm. The vasodilatory effect was induced by madagascine (0.3-100 μM) in isolated rat MRAs and the vasodilatory effect was blocked by NO synthase inhibitor L-NAME and AMPK inhibitor compound C. Madagascine (10 μM) also significantly relaxed the abnormal constriction in porcine VSM induced by SPC and the effect was abolished by compound C. Madagascine significantly increased the phosphorylation of endothelial nitric oxide synthase (eNOS) in endothelial cells while decreasing the phosphorylation of myosin phosphatase target subunit 1 (MYPT1) in VSM cells. Madagascine-induced vasodilatation was abrogated using small interfering RNA knockdown of AMPK. In summary, madagascine exerted vasodilatation through activating AMPK, leading to the activation of eNOS in endothelium and inhibition of ROCK/MYPT1 in VSM. This study suggests the potential value of madagascine in amelioration of vasospasm related cardiovascular diseases.

Role of tagged SNPs of the AGT gene in causing susceptibility to essential hypertension

AIM

Angiotensinogen (AGT) is one of the candidate genes that has been extensively investigated for association of its variants with essential hypertension. Studies focusing on the contribution of tagged single nucleotide polymorphisms (SNPs) in the AGT gene are limited and lacking from Indian population. Hence, the present study was carried out to examine the role of five tagged SNPs viz., g.6147G>A (rs7539020), g.5978A>G (rs2493134); g.6241T>C (rs1078499), g.7781G>T (rs11122577), and g.5855G>A (rs3789678) in the development of hypertension.

MATERIALS AND METHODS

202 hypertensives and 222 normotensives were screened for five tagged SNPs using the method of polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The present study revealed significant association of g.5855G>A polymorphism with essential hypertension in different logistic regression models wherein protection was conferred by g.5855G>A against developing the condition. The polymorphism led to the creation of new exonic splicing enhancer and destruction of exonic splicing silencer site thereby enhancing the process of mRNA splicing. The haplotypes AGTG and GACG were found to have a significant protective effect. Other polymorphisms did not show any significant association with hypertension.

CONCLUSION

The present study is the first one to report the protective role of g.5855G>A polymorphism in the development of essential hypertension. The results reflect possibility of ethnic variation in the contribution of g.5855G>A polymorphism of the AGT gene to essential hypertension.

DNA methylation and hypertension: emerging evidence and challenges

Hypertension is a multifactorial disease influenced by an interaction of environmental and genetic factors. The exact molecular mechanism of hypertension remains unknown. Aberrant DNA methylation is the most well-defined epigenetic modification that regulates gene transcription. However, studies on the association between DNA methylation and hypertension are still in their infancy. This review summarizes the latest evidence and challenges regarding the role of DNA methylation on 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.

Risk given by AGT polymorphisms in inducing susceptibility to essential hypertension among isolated populations from a remote region of China: A case-control study among the isolated populations

INTRODUCTION

Hypertension is a serious risk factor affecting up to 30% of the world's population with a heritability of more than 30-50%. The aim of this study was to investigate the contribution of the polymorphisms localized in the angiotensinogen (AGT) gene, a main component of the renin-angiotensin-aldosterone system, in inducing the susceptibility to essential hypertension (EH) among isolated populations (Yi and Hani minorities) with low prevalence rate from the remote region of Yunnan in China.

METHODS

A case-control association study was performed, and all subjects were genotyped for the seven single nucleotide polymorphisms localized in the AGT region by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Three polymorphisms, i.e. rs5046, rs5049, and rs2478544, were significantly associated with EH among the Hani minority. The associations, found in the Yi minority, did not reach a conclusive level of statistical significance. The polymorphisms of rs2478544 and rs5046 caused the transformations of exonic splicing enhancer sites and transcription factor binding sites, respectively, in the bioinformatic analyses. The haplotype-rs5046T, rs5049A, rs11568020G, rs3789679C, rs2478544C was susceptible for EH among the Hani minority.

CONCLUSION

Our findings suggested that the AGT polymorphisms have played a vital role in determining an individual's susceptibility to EH among the isolated population, which would be helpful for EH management in the remote mountainous region of Yunnan in China.

Polymorphisms within angiotensin II receptor type 1 gene associated with essential hypertension in Chinese Hani and Yi minorities

INTRODUCTION

Angiotensin II receptor type 1 mediates the major cardiovascular effects of angiotensin II to regulate blood pressure. Polymorphisms of angiotensin II receptor type 1 are associated with essential hypertension, but the results are inconsistent and conflicting. The aim of the present study is to assess the association between angiotensin II receptor type 1 polymorphisms and essential hypertension risk in Chinese Hani and Yi minorities.

METHODS

This study recruited 692 unrelated Chinese Hani subjects (case vs. control = 346:346) and 615 unrelated Chinese Yi subjects (case vs. control = 303:312). Twelve selected single nucleotide polymorphisms in the angiotensin II receptor type 1 gene were genotyped using a polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

Statistical analysis indicated that the GC+CC genotype of rs387967 was significantly associated with the decreased susceptibility to essential hypertension compared with GG in a Yi population (odds ratio = 0.58, 95% confidence intervals 0.41-0.83, P = 0.003). Allele C was a protective allele for essential hypertension (odds ratio = 0.78, 95% confidence intervals 0.61-0.99, P = 0.040). This association was confirmed respectively by comparing systolic blood pressure and diastolic blood pressure between different genotypes and between different alleles, which indicated that the genotype (GC+CC) had a tendency of lower systolic blood pressure and diastolic blood pressure than GG (PSBP = 3.716 × 10(-4), PDBP = 1.187 × 10(-3)); Carriers with C had lower systolic blood pressure and diastolic blood pressure (PSBP = 7.301 × 10(-3), PDBP = 9.142 × 10(-4)). Another single nucleotide polymorphism (rs2638360) was analysed in a Hani minority, then replicated in a Yi minority. The C allele showed a consistent risk trend for essential hypertension in two independent populations (Hani: odds ratio = 1.74, 95% confidence intervals 1.01-2.99, P = 0.046; Yi: odds ratio = 1.27, 95% confidence intervals 0.82-1.96, P = 0.277). Meta-analysis revealed that the C allele could significantly increase the risk of essential hypertension (odds ratio = 1.44, 95% confidence intervals 1.02-2.02, P = 0.037).

CONCLUSION

Our findings suggest that rs387967 is associated with the susceptibility to essential hypertension in a Yi population and the tendency was replicated in systolic blood pressure and diastolic blood pressure detection. Meta-analysis revealed that C allele of rs2638360 could significantly increase the risk of essential hypertension. The two single nucleotide polymorphisms maybe play a role in the pathology of essential hypertension.

Asian women have attenuated sympathetic activation but enhanced renal-adrenal responses during pregnancy compared to Caucasian women

Asians have a lower prevalence of hypertensive disorders of pregnancy than Caucasians. Since sympathetic overactivity and dysregulation of the renal-adrenal system (e.g. low aldosterone levels) have been found in preeclamptic women, we hypothesized that Asians have lower muscle sympathetic nerve activity (MSNA) and greater aldosterone concentrations during normal pregnancy than Caucasians. In a prospective study, blood pressure (BP), heart rate (HR), and MSNA were measured during supine and upright tilt (30 deg and 60 deg for 5 min each) in 9 Asians (32 ± 1 years (mean ± SEM)) and 12 Caucasians (29 ± 1 years) during pre-, early (≤8 weeks of gestation) and late (32-36 weeks) pregnancy, and post-partum (6-10 weeks after delivery). Supine MSNA increased with pregnancy in both groups (P < 0.001); it was significantly lower in Asians than Caucasians (14 ± 3 vs. 23 ± 3 bursts min(-1) and 16 ± 5 vs. 30 ± 3 bursts min(-1) in early and late pregnancy, respectively; P = 0.023). BP decreased during early pregnancy (P < 0.001), but was restored during late pregnancy. HR increased during pregnancy (P < 0.001) with no racial difference (P = 0.758). MSNA increased during tilting and it was markedly lower in Asians than Caucasians in late pregnancy (31 ± 6 vs. 49 ± 3 bursts min(-1) at 60 deg tilt; P = 0.003). Upright BP was lower in Asians, even in pre-pregnancy (P = 0.006), and this racial difference persisted during pregnancy. Direct renin and aldosterone increased during pregnancy (both P < 0.001); these hormones were greater in Asians (P = 0.086 and P = 0.014). Thus, Asians have less sympathetic activation but more upregulated renal-adrenal responses than Caucasians during pregnancy. These results may explain, at least in part, why Asian women are at low risk of hypertensive disorders in pregnancy.

A polymorphism of the renin gene rs6682082 is associated with essential hypertension risk and blood pressure levels in Korean women

PURPOSE

The aim of the present study was to investigate associations between the renin gene (REN) and the risk of essential hypertension and blood pressure (BP) levels in Koreans.

MATERIALS AND METHODS

To outline the functional role of a single nucleotide polymorphism in the transcription of the REN gene, we conducted a case-control study of 1975 individuals: 646 hypertension (HT) patients and 1329 ethnically and age-matched normotensive subjects.

RESULTS

Logistic regression analysis indicated that the genotypes AA/AG were strongly associated with risk of HT (odds ratio, 1.493; 95% confidence interval, 1.069-2.086, p=0.018) in female subjects. The genotypes AA/AG also showed significant association with higher blood pressure levels, both systolic and diastolic, in postmenopausal HT women (p=0.003 and p=0.017, respectively). Analysis of the promoter containing rs6682082 revealed a 2.4±0.01-fold higher activity in the A variant promoter than the G variant promoter, suggesting that rs6682082 is itself a functional variant.

CONCLUSION

We suggest that the A allele of rs6682082 is a positive genetic marker for predisposition to essential hypertension and high BP in Korean women and may be mediated through the transcriptional activation of REN.

Elevated blood pressure: Our family's fault? The genetics of essential hypertension

AIM

To provide an updated review on current genetic aspects possibly affecting essential hypertension (EH), and to further elucidate their role in EH.

METHODS

We searched for genetic and epigenetic factors in major studies associated with EH between Jan 2008-Oct 2013 using PubMed. We limited our search to reviews that discussed mostly human studies, and were accessible through the university online resource. We found 11 genome wide association studies (GWAS), as well as five methylation and three miRNA studies that fit our search criteria. A distinction was not made between genes with protective effects or negative effects, as this article is only meant to be a summary of genes associated with any aspect of EH.

RESULTS

We found 130 genes from the studies that met our inclusion/exclusion criteria. Of note, genes with multiple study references include: STK39, CYP17A1, MTHFR-NPPA, MTHFR-NPPB, ATP2B1, CSK, ZNF652, UMOD, CACNB2, PLEKHA7, SH2B3, TBX3-TBX5, ULK4, CSK-ULK3, CYP1A2, NT5C2, CYP171A, PLCD3, SH2B3, ATXN2, CACNB2, PLEKHA7, SH2B3, TBX3-TBX5, ULK4, and HFE. The following genes overlapped between the genetic studies and epigenetic studies: WNK4 and BDKRB2. Several of the identified genes were found to have functions associated with EH. Many epigenetic factors were also correlated with EH. Of the epigenetic factors, there were no articles discussing siRNA and its effects on EH that met the search criteria, thus the topic was not included in this review. Among the miRNA targets found to be associated with EH, many of the genes involved were also identified in the GWAS studies.

CONCLUSION

Genetic hypertension risk algorithms could be developed in the future but may be of limited benefit due to the multi-factorial nature of EH. With emerging technologies, like next-generation sequencing, more direct causal relationships between genetic and epigenetic factors affecting EH will likely be discovered creating a tremendous potential for personalized medicine using pharmacogenomics.

Role of poly (ADP-ribose)-polymerase and its signaling pathway with renin-angiotensin aldosterone system in renal diseases

Poly(ADP-ribose) polymerase (PARP), a ubiquitous, chromatin-bound enzyme, plays a crucial role in many processes, including DNA repair, cell death, metabolism, and inflammatory responses, by activating DNA repair pathways responsible for cellular survival. Renin-angiotensin-aldosterone system (RAAS) genes encode renin, angiotensinogen, angiotensin-converting enzyme, angiotensin type-1 receptor and aldosterone synthase gene. RAAS is a hormone system which acts on multiple physiologic pathways primarily by regulating blood pressure, electrolyte and fluid homeostasis in mammals, but also by local autocrine and paracrine actions. The current status quo of scientific evidence shows that there might be a signaling pathway between PARP and RAAS. Herein, we review the role of PARP and its signaling pathways with RAAS in renal diseases.