Analysis of polymorphism in Renin Angiotensin System and other related genes in South Indian chronic kidney disease patients

Structural and Dynamic Investigation of non-synonymous variations in Renin-AGT complex revealed altered binding via hydrogen bonding network reprogramming to accelerate the hypertension pathway

Hypertension is one of the major issues worldwide and one of the main factors involved in heart and kidney failure. Angiotensinogen and renin are key components of the renin-angiotensin-aldosterone system (RAAS), which plays an indispensable role in hypertension. The aimed of this study to find out the non-synonymous mutations and structure-based mutation-function correlation in the Renin-AGT complex and reveal the most deleterious mutations to accelerated hypertension. In the current study, we employed computational modelling and molecular simulation approaches to demonstrate the impact of specific mutations in the REN-AGT interface in hypertension. Computational algorithms i.e. PhD-SNP, PolyPhen-1, MAPP, SIFT, SNAP, PredictSNP, PolyPhen-2, and PANTHER predicted 20 mutations as deleterious in AGT while only five mutations were conformed as deleterious in the Renin protein. Investigation of the bonding analysis revealed that two mutations S107L and V193F in Renin altered the hydrogen-bonding paradigm at the interface site. Furthermore, exploration of structural-dynamic behaviors demonstrated by that these mutations also increases the structural stability to regulate the expression of disease pathway. The flexibility index of each residues and structural compactness analysis further validated the findings by portraying the difference in the dynamic behavior in contrast to the wild type. Binding energy calculations based on molecular mechanics/generalized Born surface area (MM/GBSA) methods were used which further established the binding differences between the wild type, S107L, and V193F mutant variants. The total binding energy for wild type, S107L, and V193F were reported to be -27.79 kcal/mol, -47.72 kcal/mol, and -38.25 kcal/mol respectively. In conclusion, these two mutations increase the binding free energy alongside the docking score to enhance the binding between Renin and AGT to overexpress this pathway in a hypertension disease condition. Patients with these mutations may be screened for potential therapeutic intervention.

Angiotensin II receptor type 1 A1166C modifies the association between angiotensinogen M235T and chronic kidney disease

Single nucleotide polymorphisms (SNPs) in renin-angiotensin system (RAS) genes are associated with RAS imbalance and chronic kidney disease (CKD). We performed a case-control study and meta-analysis to investigate the association between angiotensinogen (AGT) M235T polymorphism and CKD. A total of 634 patients with end-stage renal disease and 739 healthy controls were studied. We also searched PubMed and the Cochrane Library to identify prospective observational studies published before December 2015. We found that the TT and MT genotypes were associated with a higher risk of CKD than the MM genotype (odds ratio [OR]: 3.56; 95% confidence interval [CI]: 1.14-11.16 and OR: 2.93; 95% CI: 0.91-9.46, respectively). Thirty-eight study populations were included in the meta-analysis. The T allele was associated with a higher risk of CKD than the M allele in all populations (OR: 1.19; 95% CI: 1.08-1.32). The OR was 1.33 in Asians (95% CI: 1.06-1.67) and 1.10 in Caucasians (95% CI: 1.02-1.18). Evaluation of gene-gene and gene-environment interactions using epistasis analysis revealed an interaction between AGT M235T and angiotensin II receptor type 1 A1166C in CKD (OR: 0.767; 95% CI: 0.609-0.965). Genetic testing for CKD in high-risk individuals may be an effective strategy for CKD prevention.

Angiotensin II Type 1 receptor (AGTR1) gene polymorphisms are associated with vascular manifestations in patients with systemic sclerosis (SSc)

INTRODUCTION

Systemic sclerosis (SSc) shows variable clinical expression in different ethnic groups; vascular abnormalities are a prominent feature of this disease and its clinical expression may be influenced by genetic factors.

PATIENTS AND METHODS

Herein, we describe 15 polymorphisms of the renin-angiotensin-aldosterone pathway in 170 Mexican admixed SSc patients (defined as patients with Mexican ancestry for at least 3 generations) and 199 healthy controls. We determined the presence of angiotensin II Type 1 receptor (AGTR1), angiotensin converting enzyme (ACE) and Endothelin 1 single nucleotide polymorphisms (SNPs) using 5' exonuclease TaqMan genotyping assays on a 7900HT real-time fast polymerase chain reaction (PCR) system.

RESULTS

These polymorphisms had a similar distribution between SSc patients and controls, but we found that the AGTR1 G-680T (rs275652) (p = 0.02; OR 3.5; 95%CI 1.2-10.4) and AGTR1 A-119G (rs275653) (p = 0.008; OR 4.2; 95% CI 1.5-12.1) polymorphisms were associated with severe vascular involvement in our SSc patients.

CONCLUSIONS

This is the first report of the association of these polymorphisms with vasculopathy in Mexican admixed SSc patients. Our findings suggested that the angiotensin II Type 1 receptor genotype may influence the clinical expression of vasculopathy in these patients. Functional analyses should follow.

Prevalence of angiotensin converting enzyme (ACE) gene insertion/deletion polymorphism in South Indian population with hypertension and chronic kidney disease

Context:

Chronic Kidney Disease (CKD) is associated with a high risk of developing further severe complications such as, cardiovascular disease and eventually End Stage Renal Disease (ESRD) leading to death. Hypertension plays a key role in the progression of renal failure and is also a chief risk factor for the occurrence of End Stage Renal Disease (ESRD).

Aim:

This study investigates the possible association of insertion (I) and deletion (D) polymorphism of ACE gene in patients of Chronic Kidney Disease (CKD) with and without hypertension (HT).

Settings and Design:

Total 120 participants with 30 members in each group (Control, HT, CKD and CKD-HT) were chosen followed by informed consent.

Materials and Methods:

Blood samples were collected and subjected to biochemical analyses and nested PCR amplification was performed to genotype the DNA, for ACE I/D using specific primers.

Statistical Analysis:

Statistical analyses were performed using SPSS version 13. Allele and genotypic frequency was calculated by direct gene counting method. Comparison of the different genotypes was done by using Chi square test. Odd's ratios were calculated with a 95% confidence interval limit.

Results:

The ACE genotype were distributed as II, 27 (90%); DD, 2 (6.67%) and ID, 1 (3.33%) in control, II, 1 (3.33%); DD, 5 (16.67%) and ID, 24 (80%) in HT, II, 4 (13.33%); DD, 24 (80%) and ID, 2 (6.67%) in CKD and II, 0 (0%); DD, 2 (6.67%) and ID, 28 (93.33%) in CKD-HT group.

Conclusions:

D allele of ACE gene confers a greater role in genetic variations underlying CKD and hypertension. This result suggest that CKD patients should be offered analysis for defects in ACE I/D polymorphisms, especially if they are hypertensive.

The role of renin-angiotensin-aldosterone system genes in the progression of chronic kidney disease: findings from the Chronic Renal Insufficiency Cohort (CRIC) study

BACKGROUND

We conducted single-marker, gene- and pathway-based analyses to examine the association between renin-angiotensin-aldosterone system (RAAS) variants and chronic kidney disease (CKD) progression among Chronic Renal Insufficiency Cohort study participants.

METHODS

A total of 1523 white and 1490 black subjects were genotyped for 490 single nucleotide polymorphisms (SNPs) in 12 RAAS genes as part of the ITMAT-Broad-CARe array. CKD progression phenotypes included decline in estimated glomerular filtration rate (eGFR) over time and the occurrence of a renal disease event, defined as incident end-stage renal disease or halving of eGFR from baseline. Mixed-effects models were used to examine SNP associations with eGFR decline, while Cox proportional hazards models tested SNP associations with renal events. Gene- and pathway-based analyses were conducted using the truncated product method. All analyses were stratified by race, and a Bonferroni correction was applied to adjust for multiple testing.

RESULTS

Among white and black participants, eGFR declined an average of 1.2 and 2.3 mL/min/1.73 m(2)/year, respectively, while renal events occurred in a respective 11.5 and 24.9% of participants. We identified strong gene- and pathway-based associations with CKD progression. The AGT and RENBP genes were consistently associated with risk of renal events in separate analyses of white and black participants (both P < 1.00 × 10(-6)). Driven by the significant gene-based findings, the entire RAAS pathway was also associated with renal events in both groups (both P < 1.00 × 10(-6)). No single-marker associations with CKD progression were observed.

CONCLUSIONS

The current study provides strong evidence for a role of the RAAS in CKD progression.

Renin-angiotensin-aldosterone system related gene polymorphisms and urinary total arsenic is related to chronic kidney disease

A recent study demonstrated that an increased risk of chronic kidney disease (CKD) was associated with high urinary total arsenic levels. However, whether genomic instability is related to CKD remains unclear. An association between CKD and genetic polymorphisms of regulation enzymes of the renin-angiotensin-aldosterone system (RAAS), such as angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II type I receptor (AT1R), and aldosterone synthase (CYP11B2) has not been shown. The aim of the present study was to investigate the relationship between arsenic, genetic polymorphisms of RAAS enzymes and CKD. A total of 233 patients and 449 age- and gender-matched controls were recruited from the Taipei Medical University Hospital, Taipei Municipal Wan Fang Hospital and the Shin Kong Wu Ho-Su Memorial Hospital. Concentrations of urinary arsenic were determined by a high-performance liquid chromatography-linked hydride generator, and atomic absorption spectrometry. Polymorphisms of ACE(I/D), AGT(A[-20]C), (T174M), (M235T), AT1R(A1166C) and CYP11B2(C[-344]T) were examined by polymerase chain reaction and restriction fragment length polymorphism. Subjects carrying the CYP11B2 TT genotype had a higher odds ratio (OR), 1.39 (0.96-2.01), of CKD; while those with the AGT(A[-20]C) CC genotype had an inverse OR of CKD (0.20 (0.05-0.81)), and a high-risk genotype was defined as A/A+A/C for AGT(A[-20C]) and T/T for CYP11B2(C[-344]T). The trend test showed a higher OR for CKD in patients who had either high urinary total arsenic levels or carried the high-risk genotype, or both, compared to patients with low urinary total arsenic levels, who carried the low-risk genotype, and could also be affected by the hypertension or diabetes status.

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.

Angiotensin-converting enzyme insertion/deletion polymorphism contributes high risk for chronic kidney disease in Asian male with hypertension--a meta-regression analysis of 98 observational studies

Background

Associations between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphisms and chronic kidney disease (CKD) have been extensively studied, with most studies reporting that individuals with the D allele have a higher risk. Although some factors, such as ethnicity, may moderate the association between ACE I/D polymorphisms and CKD risk, gender-dependent effects on the CKD risk remain controversial.

Objectives

This study investigated the gender-dependent effects of ACE I/D polymorphisms on CKD risk.

Data sources

PubMed, the Cochrane library, and EMBASE were searched for studies published before January 2013.

Study eligibility criteria, participants, and interventions

Cross-sectional surveys and case–control studies analyzing ACE I/D polymorphisms and CKD were included. They were required to match the following criteria: age >18 years, absence of rare diseases, and Asian or Caucasian ethnicity.

Study appraisal and synthesis methods

The effect of carrying the D allele on CKD risk was assessed by meta-analysis and meta-regression using random-effects models.

Results

Ethnicity [odds ratio (OR): 1.24; 95% confidence interval (CI): 1.08–1.42] and hypertension (OR: 1.55; 95% CI: 1.04–2.32) had significant moderate effects on the association between ACE I/D polymorphisms and CKD risk, but they were not significant in the diabetic nephropathy subgroup. Males had higher OR for the association between ACE I/D polymorphisms and CKD risk than females in Asians but not Caucasians, regardless of adjustment for hypertension (p<0.05). In subgroup analyses, this result was significant in the nondiabetic nephropathy group. Compared with the I allele, the D allele had the highest risk (OR: 3.75; 95% CI: 1.84–7.65) for CKD in hypertensive Asian males.

Conclusions and implications of key findings

The ACE I/D polymorphisms may incur the highest risk for increasing CKD in hypertensive Asian males.

Angiotensinogen gene haplotype is associated with the prevalence of Japanese non-alcoholic steatohepatitis

AIM

  Non-alcoholic steatohepatitis (NASH) patients frequently have hypertension, which is considered to be an important predictive factor for the subsequent development of hepatic fibrosis. The renin-angiotensin system is also known to contribute to the progression of NASH. Various types of functional single-nucleotide polymorphisms (SNPs) involved in the development of NASH have been proposed. Angiotensinogen (AGT) gene SNPs related to cardiovascular diseases have been reported. We aimed to evaluate the involvement of the AGT gene haplotype in Japanese NASH patients.

METHODS

  Previously described genotypes of SNPs of the AGT gene, rs4762 C/T polymorphism (T207M), rs699 C/T polymorphism (T268M), and rs7079 C/A polymorphism (C11537A), were determined in 124 Japanese biopsy-proven NASH patients and 150 healthy volunteers (controls).

RESULTS

  The allele and genotype frequencies in rs4762 and rs699 SNPs in NASH patients were similar to those in controls, while the frequency of the A allele and A/- genotype in rs7079 SNPs were much higher in NASH patients than in controls. In addition, the 3-SNP haplotype CTA was significantly over-represented in NASH patients compared with controls. Regarding clinical features of NASH patients, diastolic blood pressures in patients with the CTA/- genotype were much higher than in patients with other genotypes.

CONCLUSIONS

  We found a 3-SNP haplotype of the AGT gene that is involved in the development of NASH and influences hypertension in NASH patients. These results provide new insight into the therapy of NASH patients with the CTA haplotype using ACE inhibitors or angiotensin II type 1 receptor blockers.

Genetic polymorphism of ACE and the angiotensin II type1 receptor genes in children with chronic kidney disease

AIM AND METHODS

We investigated the association between polymorphisms of the angiotensin converting enzyme-1 (ACE-1) and angiotensin II type one receptor (AT1RA1166C) genes and the causation of renal disease in 76 advanced chronic kidney disease (CKD) pediatric patients undergoing maintenance hemodialysis (MHD) or conservative treatment (CT). Serum ACE activity and creatine kinase-MB fraction (CK-MB) were measured in all groups. Left ventricular mass index (LVMI) was calculated according to echocardiographic measurements. Seventy healthy controls were also genotyped.

RESULTS

The differences of D allele and DI genotype of ACE were found significant between MHD group and the controls (p = 0.0001). ACE-activity and LVMI were higher in MHD, while CK-MB was higher in CT patients than in all other groups. The combined genotype DD v/s ID+II comparison validated that DD genotype was a high risk genotype for hypertension .~89% of the DD CKD patients were found hypertensive in comparison to ~ 61% of patients of non DD genotype(p = 0.02). The MHD group showed an increased frequency of the C allele and CC genotype of the AT1RA1166C polymorphism (P = 0.0001). On multiple linear regression analysis, C-allele was independently associated with hypertension (P = 0.04).

CONCLUSION

ACE DD and AT1R A/C genotypes implicated possible roles in the hypertensive state and in renal damage among children with ESRD. This result might be useful in planning therapeutic strategies for individual patients.

Association of angiotensin II type 1-receptor gene polymorphisms with the risk of developing hypertension in Mexican individuals

INTRODUCTION

Hypertension is a complex disease in which a significant interaction between genetic and environmental factors takes place. The renin-angiotensin system plays an important role regulating blood pressure to maintain homeostasis and vascular tone. In the present work, the role of angiotensin II type 1-receptor (AGTR1) gene polymorphisms as susceptibility markers for hypertension was evaluated.

MATERIALS AND METHODS

Five polymorphisms in the AGTR1 gene were genotyped by 5' exonuclease TaqMan genotyping assays in 239 hypertensive and 371 non-hypertensive individuals.

RESULTS

A similar distribution of rs275651, rs275652, rs275653, and rs5183 polymorphisms was observed in both studied groups. Different distribution of rs5182 genotypes was observed between the studied groups (p = 0.016). According to the co-dominant model, individuals with rs5182 CC genotype have a 1.83-fold increased risk of developing hypertension (p = 0.009). Polymorphisms were distributed in two blocks: block 1 included the rs275651, rs275652, and rs275653 polymorphisms, whereas block 2 included the rs5183 and rs5182 polymorphisms. Individuals with hypertension showed increased frequency of 'CA' haplotype of block 2 when compared to non-hypertensive individuals (p = 0.015, odds ratio = 1.33).

CONCLUSION

The results suggest that the rs5182 gene polymorphism could be involved in the risk of developing hypertension in Mexican individuals.