Genetic variants in the renin-angiotensin system genes are associated with cardiovascular-renal-related risk factors in Mexican Americans

Association of the rs5186 polymorphism of the AGTR1 gene with decreased eGFR in patients with type 2 diabetes from Mexico City

BACKGROUND

Early biomarkers search for Diabetic Kidney Disease (DKD) in patients with Type 2 Diabetes Mellitus (T2DM), as genetic markers to identify vulnerable carriers of the disease even before Glomerular Filtration Rate (GFR) decline or microalbuminuria development, has been relevant during the last few years. The rs5186 (A116C) polymorphism of the Angiotensin II Receptor Type I gene (AGTR1), has been associated to multiple effects of renal injury risk, commonly detected in patients with Diabetes Mellitus (DM). It has been described that rs5186 could have an effect in stability proteins that assemble Angiotensin II Receptor Type I (AT1), modifying its action, which is why it should be considered as a risk factor for Chronic Kidney Disease (CKD), characterized by a GFR progressive reduction. Even though, the association between rs5186 AGTR1 gene polymorphism and DKD in patients with T2DM has been controversial, inconclusive, and even absent. This disputable issue might be as a result of association studies in which many and varied clinical phenotypes included are contemplated as CKD inductors and enhancers. Although, the sample sizes studied in patients with T2DM are undersized and did not have a strict inclusion criteria, lacking of biochemical markers or KDOQI classification, which have hindered its examination.

OBJECTIVE

The aim of our study was to establish an association between rs5186 AGTR1 gene polymorphism and GFR depletion, assessed as a risk factor to DKD development in patients with T2DM.

METHODS

We analyzed 297 not related patients with T2DM, divided into 221 controls (KDOQI 1) and 76 cases (KDOQI 2). Arterial pressure, anthropometric and biochemical parameters were measured. rs5186 of AGTR1 genotyping was performed by TaqMan assay real-time PCR method. Allele and genotype frequencies, and Hardy-Weinberg equilibrium were measured. Normality test for data distribution was analyzed by Shapiro-Wilk test, variable comparison by Student's t-test for continuous variables, and Chi-squared test for categorical variables; ANOVA test was used for mean comparison of more than two groups. Effect of rs5186 to DKD was estimated by multiple heritability adjustment models for risk variables of DKD. Statistical significance was indicated by p<0.05. Data was analyzed using Statistical Package STATA v11 software.

RESULTS

Dominant and Over-dominant models showed a likelihood ratio to GFR depletion of 1.89 (1.05-3.39, p=0.031) and 2.01 (1.08-3.73, p=0.023) in patients with T2DM. Risk factor increased to 2.54 (1.10-5.89) in women in Over-dominant model.

CONCLUSION

In clinical practice, most of nephropathies progress at a slow pace into a total breakdown of renal function, even asymptomatic. This is the first study, reporting that rs5186 polymorphism of AGTR1 gene contribution to GFR depletion, and this could be evaluated as a predisposing factor for DKD in patients with T2DM.

Interaction of sex, age, body mass index and race on hypertension risk in the American population: a cross-sectional study

BACKGROUND

The joint effects of sex, age, body mass index (BMI) and race on hypertension have not been fully addressed. Herein, we carried out this study aiming to investigate the possible effects of the interaction of sex, age, BMI and race on risk of hypertension.

METHODS

By using the data of a sample-adjusted 2656 women and 2515 men in American National Health and Nutrition Examination Survey 2015-16, we analyzed the interaction of sex, age, BMI and race by logistic regression models, followed by strata-specific analyses. Hypertension was defined as a systolic blood pressure ≥130 mmHg/diastolic blood pressure ≥80 mmHg or taking anti-hypertensive medication.

RESULTS

A total of 5171 participants were included in analysis, and the prevalence of hypertension was 53.68%. The interactive effect of sex and age, BMI and age, race and age were statistically significant on hypertension. Strata-specific analyses showed that female at 40 years and above were positively associated with hypertension than those at 20-39 years. The associations also persistence in male. The risk estimates for age ≥40 on hypertension were consistently positive across all overweight/obesity and race groups. The effect was most prominent among overweight populations aged 60-80 years and Other Hispanic aged 40 years and above.

CONCLUSION

There exists interactive effect of sex and age, BMI and age, race and age on hypertension in American population. The effect of age on hypertension was more prominent in female, overweight populations and Other Hispanic populations. Differences in age, BMI and race should be considered when providing corresponding antihypertensive measures.

Correlation between gene polymorphism in angiotensin II type 1 receptor and type 2 diabetes mellitus complicated by hypertension in a population of Inner Mongolia

Background

The role of angiotensin II type 1 receptor (AT1R) as a key player in type 2 diabetes mellitus (T2DM) complicated with hypertension remains controversial. The present case-control study systematically investigated the association between gene the correct variation type in the angiotensin II type 1 receptor (AT1R) gene and type 2 diabetes mellitus complicated with hypertension in the Han population from the Inner Mongolia region, China.

Method

Here, state which variants were analysis, including age, occupation, triglyceride, systolic, diastolic, sex, culture, marital status, smoking, alcohol, BMI (body mass index), SBP (systolic blood pressure), DBP (diastolic blood pressure), TG (triglyceride), TC (total cholesterol), HDL-C (high-density lipoprotein cholesterol), LDL-C (low-density lipoprotein cholesterol), FPG (fasting plasma glucose). Genomic DNA was extracted from samples from 202 type 2 diabetic patients with hypertension and 216 type 2 diabetic patients without hypertension.

Results

Non-conditional regression analysis showed that in comparison with the TT genotype, the presence of the CC genotype for the T573 site of the AT1R gene increased the risk for diabetes mellitus complicated with hypertension by 3.219-fold (OR = 3.219, 95% CI: 1.042–9.941, P = 0.042). The results from multivariate linear regression analysis suggested the rs5182 polymorphism in the AT1R gene to be associated with diastolic blood pressure (P = 0.032). No other associations were found between the incidence of disease and the correct variation type at other sites of the AT1R gene.

Conclusions

Our results suggest that the rs5182 polymorphism in the AT1R gene is associated with diabetes complicated by hypertension in the Han population of Inner Mongolia.

Understanding the growing epidemic of type 2 diabetes in the Hispanic population living in the United States

The prevalence and incidence of type 2 diabetes (T2D) among the Hispanic population in the United States are higher than the national average. This is partly due to sociocultural factors, such as lower income and decreased access to education and health care, as well as a genetic susceptibility to obesity and higher insulin resistance. This review focuses on understanding the Hispanic population living in the United States from a multidisciplinary approach and underlines the importance of cultural, social, and biological factors in determining the increased risk of T2D in this population. An overview of the acute and chronic complications of T2D upon this population is included, which is of paramount importance to understand the toll that diabetes has upon this population, the health system, and society as a whole. Specific interventions directed to the Hispanic populations are needed to prevent and alleviate some of the burdens of T2D. Different prevention strategies based on medications, lifestyle modifications, and educational programmes are discussed herein. Diabetes self-management education (DSME) is a critical element of care of all people with diabetes and is considered necessary to improve patient outcomes. To be more effective, programmes should take into consideration cultural factors that influence the development and progression of diabetes. These interventions aim to enhance long-term effects by reducing the incidence, morbidity, and mortality of T2D in the Hispanic population of the United States.

Preeclampsia is associated with ACE I/D polymorphism, obesity and oxidative damage in Mexican women

OBJECTIVE

This study sought to determine whether the angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism, obesity and oxidative damage are risk factors for the development of preeclampsia in Mexican women.

STUDY DESIGN

A total of 66 women with preeclampsia (PE) and 37 women with normal pregnancies (NP) were included in the study. DNA was extracted from whole blood, and the ACE I/D polymorphism was evaluated by polymerase chain reaction. ACE activity and oxidative damage were assessed in plasma. The intergroup comparisons were analyzed by an analysis of variance (ANOVA) with post hoc tests. Hardy-Weinberg equilibrium (HWE) was tested by x² analysis, odds ratios (OR) were calculated as a measure of the degree of relative risk of preeclampsia, and for correlations, we used Spearman's correlation coefficient.

RESULTS

The frequency of the DD genotype was higher in PE (34.84%) than NP (10.82%). The OR of the DD genotype and D allele were associated with a 4.4-fold (CI=95% 2.24-14) and 3-fold (CI=95% 1.69-5.62) increased risk of developing PE, respectively. Major ACE activity in the DD genotype and obesity were features of the PE group; oxidative damage to proteins and a reduction in the activity of the antioxidant system showed a correlation with BMI (p<0.01).

CONCLUSION

Our results suggest that ACE I/D polymorphism, high ACE activity, body mass index and oxidative damage may play key roles in the pathogenesis of PE in the Mexican population. Furthermore, these findings could be used as predictive factors of PE.

Clinical characteristics, treatment patterns and outcomes of Hispanic hypertensive patients

Hispanics are the largest and fastest-growing minority population in the United States, currently comprising about 16.3% (52 million) of the total population. With an increased prevalence of metabolic risk factors in this population, the rate of uncontrolled hypertension (HTN) in Hispanics significantly exceeds the rates observed among non-Hispanic blacks and whites. Unfortunately, data on HTN in Hispanics remains limited due to the under-representation of Hispanics in clinical trials; with most of the data primarily restricted to observational and retrospective subgroup analyses. This article aims to review the available data on prevalence, awareness and control of HTN, risk factors and some of the challenges unique to the Hispanics population. We also discuss treatment strategies derived from large HTN trials that included Hispanics.

Gene-gene interactions in renin-angiotensin-aldosterone system contributes to end-stage renal disease susceptibility in a Han Chinese population

Objective. In this study, we investigated whether RAAS gene single nucleotide polymorphisms (SNPs) and their interactions were associated with end-stage renal stage (ESRD). Methodology and Results. This was a case-control study for 647 ESRD cases and 644 controls. AGT (M235T (rs699) and T174M (rs4762)), AGTR1 (A1166C (rs5186) and C573T (rs5182)), ACE (I/D (rs1799752) and G2350A (rs4343)), and CYP11B2 C-344T (rs1799998) were genotyped and compared between cases and controls to identify SNPs associated with ESRD susceptibility. Multifactor dimensionality reduction (MDR) was used to identify gene-gene interactions. Several RAAS genes were associated with ESRD: AGT M235T, ACE I/D, ACE G2350A, and CYP11B2 C-344T. By MDR analysis, a three-locus model (ACE ID/ACE G2350A/CYP11B2 C-344T) of gene-gene interaction was the best for predicting ESRD risk, and its maximum testing accuracy was 56.08% and maximum cross-validation consistency was 9/10. ESRD risk was higher with the simultaneous occurrence of ACE I/D DD-ACE G2350A AA. AGT, ACE, and CYP11B2 gene polymorphisms are associated with ESRD. Conclusions. The gene-gene interaction effects of ACE I/D, ACE G2350A, and CYP11B2 C-344T polymorphisms are more important than individual factors for ESRD development among Han Chinese.

Susceptibility gene search for nephropathy and related traits in Mexican-Americans

The rising global epidemic of diabetic nephropathy (DN) will likely lead to increase in the prevalence of cardiovascular morbidity and mortality posing a serious burden for public health care. Despite greater understanding of the etiology of diabetes and the development of novel treatment strategies to control blood glucose levels, the prevalence and incidence rate of DN is increasing especially in minority populations including Mexican-Americans. Mexican-Americans with type 2 diabetes (T2DM) are three times more likely to develop microalbuminuria, and four times more likely to develop clinical proteinuria compared to non-Hispanic whites. Furthermore, Mexican-Americans have a sixfold increased risk of developing renal failure secondary to T2DM compared to Caucasians. Prevention and better treatment of DN should be a high priority for both health-care organizations and society at large. Pathogenesis of DN is multi-factorial. Familial clustering of DN-related traits in MAs show that DN and related traits are heritable and that genes play a susceptibility role. While, there has been some progress in identifying genes which when mutated influence an individual's risk, major gene(s) responsible for DN are yet to be identified. Knowledge of the genetic causes of DN is essential for elucidation of its mechanisms, and for adequate classification, prognosis, and treatment. Self-identification and collaboration among researchers with suitable genomic and clinical data for meta-analyses in Mexican-Americans is critical for progress in replicating/identifying DN risk genes in this population. This paper reviews the approaches and recent efforts made to identify genetic variants contributing to risk for DN and related phenotypes in the Mexican-American population.

Angiotensin type 1 receptor resistance to blockade in the opossum proximal tubule cell due to variations in the binding pocket

Blockade of the angiotensin (ANG) II receptor type 1 (AT(1)R) with angiotensin receptor blockers (ARBs) is widely used in the treatment of hypertension. However, ARBs are variably effective in reducing blood pressure, likely due, in part, to polymorphisms in the ARB binding pocket of the AT(1)R. Therefore, we need a better understanding of variations/polymorphisms that alter binding of ARBs in heterogeneous patient populations. The opossum proximal tubule cell (OKP) line is commonly used in research to evaluate renal sodium handling and therefore blood pressure. Investigating this issue, we found natural sequence variations in the opossum AT(1)R paralleling those observed in the human AT(1)R. Therefore, we posited that these sequence variations may explain ARB resistance. We demonstrate that OKP cells express AT(1)R mRNA, bind (125)I-labeled ANG II, and exhibit ANG II-induced phosphorylation of Jak2. However, Jak2 phosphorylation is not inhibited by five different ARBs commonly used to treat hypertension. Additionally, nonradioactive ANG II competes (125)I-ANG II efficiently, whereas a 10-fold molar excess of olmesartan and the ANG II receptor type 2 blocker PD-123319 is unable to block (125)I-ANG II binding. In contrast, ANG II binding to OKP cells stably expressing rat AT(1A)Rs, which have a conserved AT(1)R-binding pocket with human AT(1)R, is efficiently inhibited by olmesartan. A novel observation was that resistance to ARB binding to opossum AT(1)Rs correlates with variations from the human receptor at positions 108, 163, 192, and 198 within the ARB-binding pocket. These observations highlight the potential utility of evaluating AT(1)R polymorphisms within the ARB-binding pocket in various hypertensive populations.

Hypertension and antihypertensive therapy in Hispanics and Mexican Americans living in the United States

Hypertension is a major independent risk factor for cardiovascular diseases, which are the most frequent cause of death worldwide. In addition, the risk of hypertension has been associated with racial and/or ethnic background. Hispanics are the largest and fastest-growing minority population in the United States, currently comprising about 16.3% (50.5 million) of the total population; these numbers will continue to increase into the next 10 years. The rate of uncontrolled hypertension in Hispanics significantly exceeds the rates observed among non-Hispanic blacks and whites. The reasons for these racial and ethnic differences in blood pressure control may include factors such as lack of access to health care, low socioeconomic status, language barriers, degree of acculturation, poor doctor-patient communication, and genetic factors. This article provides an up-to-date summary of epidemiological and treatment aspects of high blood pressure in the US Hispanic population. Because Mexican Americans constitute approximately 66% of US Hispanics, data sources that focus on Mexican Americans are also discussed.

Genetics of hypertension and cardiovascular disease and their interconnected pathways: lessons from large studies

Blood pressure (BP), hypertension (HT) and cardiovascular disease (CVD) are common complex phenotypes, which are affected by multiple genetic and environmental factors. This article describes recent genome-wide association studies (GWAS) that have reported causative variants for BP/HT and CVD/heart traits and analyzes the overlapping associated gene polymorphisms. It also examines potential replication of findings from the HyperGEN data on African Americans and whites. Several genes involved in BP/HT regulation also appear to be involved in CVD. A better picture is emerging, with overlapping hot-spot regions and with interconnected pathways between BP/HT and CVD. A systemic approach to full understanding of BP/HT and CVD development and their progression to disease may lead to the identification of gene targets and pathways for the development of novel therapeutic interventions.

New evidence for the fetal insulin hypothesis: fetal angiotensinogen M235T polymorphism is associated with birth weight and elevated fetal total glycated hemoglobin at birth

BACKGROUND

Low birth weight is associated with an increased risk of cardiovascular events in later life. Insulin resistance is a key finding in adult patients with cardiovascular diseases. The neonatal phenotype of an individual with insulin resistance might be low birth weight, as insulin influences fetal growth. The renin-angiotensin-aldosterone system has been associated with cardiovascular disease and insulin resistance. We analyzed whether fetal polymorphisms of the angiotensinogen (AGT) and angiotensin-converting enzyme genes influence birth weight and/or fetal total glycated hemoglobin (fTGH), a surrogate parameter of fetal insulin resistance at birth.

METHOD

In 1132 white women delivering singletons, neonatal umbilical blood samples and clinical data of the mothers and newborns were obtained. Newborns were genotyped with respect to the AGT M235T and angiotensin-converting enzyme insertion/deletion polymorphism.

RESULTS

The AGT M235T TT polymorphism is associated with reduced birth weight (TT: 3288 g versus TM + MM: 3435 g, P < 0.05). Furthermore, newborns with a high percentage of fTGH (>6.5%) are more likely to have the TT genotype than those with normal fTGH (<or=6.5%, P < 0.05). With higher cutoffs for fTGH, the significance increases to P less than 0.005. No association was seen between these parameters and the fetal angiotensin-converting enzyme insertion/deletion phenotype.

CONCLUSION

The fetal AGT M235T polymorphism is associated with low birth weight and elevated fetal fTGH at birth. Previous findings show that elevated fetal fTGH correlates with low birth weight and that higher activity of the renin-angiotensin-aldosterone system is an independent risk factor for the development of diabetes mellitus and coronary artery disease. Therefore, our data are supportive of the fetal insulin hypothesis.

Associations between genetic variants in the ACE, AGT, AGTR1 and AGTR2 genes and renal function in the Multi-ethnic Study of Atherosclerosis

BACKGROUND/AIMS

Some studies suggest that polymorphisms in angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II type I receptor (AGTR1) and angiotensin II type II receptor (AGTR2) genes may contribute to renal function variation.

METHODS

Genotyping for single nucleotide polymorphisms (SNPs) in these candidate genes was performed in 2,847 participants from four racial/ethnic groups (African American, Chinese, White and Hispanic) without known cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis. SNP and haplotype analyses were performed to determine associations between genotypes and cross-sectional renal function measurements, including urine albumin excretion (UAE) and estimated glomerular filtration rate (eGFR) using serum creatinine and cystatin C.

RESULTS

Twenty-four ACE SNPs, 10 AGT SNPs, 15 AGTR1 SNPs and 6 AGTR2 SNPs were typed successfully. After adjusting for ancestry, age and gender, 3 SNPs (AGT M235T, AGT rs2148582 and AGTR1 rs2131127) showed associations with an empiric p value <0.05 with the same phenotype in multiple racial/ethnic groups, suggesting replication. The AGT M235T SNP has been shown previously to be associated with diabetic and hypertensive nephropathy.

CONCLUSIONS

These data suggest that genetic polymorphisms in the renin-angiotensin system are associated with renal phenotypes in the general population, but that many associations differ across racial/ethnic groups.

Genotypic interactions of renin-angiotensin system genes with diabetes type 2 in a Tunisian population

AIMS

To explore the role of genetic variants of angiotensinogen (AGT M235T), angiotensin-converting enzyme (ACE I/D), and angiotensin type 1 receptor (AT1R A1166C) as predictors of diabetes risk and to examine their combined effects on type 2 diabetes mellitus (T2DM) patients.

MAIN METHODS

One hundred and fourteen T2DM patients were compared to 175 healthy controls with similar age and sex.

KEY FINDINGS

The genotypic frequencies for all three genes alone were significantly associated with increased risk of developing diabetes. Logistic regression analysis of classic coronary risk factors and the genetic polymorphisms demonstrated that hypertension and ACE DD genotype were the most significant contributors to T2DM. For the renin-angiotensin system (RAS) genes, the risk of T2DM in individuals with one risk genotype was 1.9 (95%CI: 1.1-3.0, p=0.017) higher than those with zero risk genotype. Individuals who carried two risk genotypes had a 4.0 (95%CI 1.7-9.4, p=0.001) times higher risk of T2DM than those who did not carry any risk genotypes of the RAS genes. Most interestingly, the risk of T2DM for individuals with three risk genotypes was 26.2 (95%CI: 5.8-117.9, p<0.001) higher than those with zero risk genotype.

SIGNIFICANCE

The results of the present study imply that genotyping of renin-angiotensin system genes could become an important part of the clinical process of risk identification for T2DM in Tunisian population.

Differences in albuminuria between Hispanics and whites: an evaluation by genetic ancestry and country of origin: the multi-ethnic study of atherosclerosis

BACKGROUND

Reports show higher prevalence of albuminuria among Hispanics compared with whites. Differences by country of origin or genetic background are unknown.

METHODS AND RESULTS

In Multi-Ethnic Study of Atherosclerosis, we studied the associations of both genetic ancestry and country of origin with albumin to creatinine ratio among 1417 Hispanic versus white participants using multivariable linear regression and back transforming beta coefficients into relative difference (%RD, 95% CI). Percentage European, Native American, and African ancestry components for Hispanics were estimated using genetic admixture analysis. The proportions of European, Native American, and African genetic ancestry differed significantly by country of origin (P<0.0001); Mexican/Central Americans had the highest Native American (41+/-13%), Puerto Ricans had the highest European (61+/-15%), and Dominicans had the highest African (39+/-21%) ancestry. Hispanic ethnicity was associated with higher albumin/creatinine ratio compared with whites, but the association varied with the country of origin (adjusted P interaction=0.04). Mexican/Central Americans and Dominicans had higher albumin/creatinine ratio compared with whites after adjustment (RD 19%, 2% to 40% and RD 27%, 1% to 61%), but not Puerto Ricans (RD 8%, -12% to 34%). Higher Native American ancestry was associated with higher albuminuria after age and sex adjustment among all Hispanics (RD 11%, 1% to 21%) but was attenuated after further adjustment. Higher European ancestry was independently associated with lower albumin/creatinine ratio among Puerto Ricans (-21%, -34% to -6%) but not among Mexican/Central Americans and Dominicans.

CONCLUSIONS

Hispanics are a heterogeneous group with varying genetic ancestry. Risks of albuminuria differ across the country of origin groups. These differences may be due, in part, to differences in genetic ancestral components.