Association between two genetic polymorphisms of the renin-angiotensin-aldosterone system and diabetic nephropathy: a meta-analysis

The Molecular Mechanism of Renal Tubulointerstitial Inflammation Promoting Diabetic Nephropathy

Diabetic nephropathy (DN) is a common complication affecting many diabetic patients, leading to end-stage renal disease. However, its pathogenesis still needs to be fully understood to enhance the effectiveness of treatment methods. Traditional theories are predominantly centered on glomerular injuries and need more explicit explanations of recent clinical observations suggesting that renal tubules equally contribute to renal function and that tubular lesions are early features of DN, even occurring before glomerular lesions. Although the conventional view is that DN is not an inflammatory disease, recent studies indicate that systemic and local inflammation, including tubulointerstitial inflammation, contributes to the development of DN. In patients with DN, intrinsic tubulointerstitial cells produce many proinflammatory factors, leading to medullary inflammatory cell infiltration and activation of inflammatory cells in the interstitial region. Therefore, understanding the molecular mechanism of renal tubulointerstitial inflammation contributing to DN injury is of great significance and will help further identify key factors regulating renal tubulointerstitial inflammation in the high glucose environment. This will aid in developing new targets for DN diagnosis and treatment and expanding new DN treatment methods.

The genetic side of diabetic kidney disease: a review

BACKGROUND

Diabetic kidney disease (DKD) is one of the most common complications of diabetes, with approximately 30-40% of patients with type 1 diabetes mellitus and 20% of patients with type 2 diabetes mellitus eventually developing DKD. If DKD is not controlled in the early clinical stage and proteinuria develops, the disease will progress to end-stage renal disease. The pathogenesis of DKD remains largely unknown and is multifactorial, likely due to interactions between genetic and environmental factors. Familial clustering also supports a critical role of hereditary factors in DKD. The development of gene detection technology has promoted the exploration of DKD susceptibility genes in different cohorts of patients with diabetes. Identifying susceptibility genes can provide insights into the pathogenesis of DKD, as well as a basis for its clinical diagnosis and therapy.

RESULTS

Numerous candidate gene loci have been found to be associated with DKD, many of which play critical regulatory roles in the pathogenesis of this disease, including genes involved in glycol-metabolism, lipid metabolism, the renin-angiotensin-aldosterone system, inflammation and oxidative stress. In this review, we summarize the functions of several susceptibility genes involved in the development of DKD.

CONCLUSION

Based on our findings, we recommend that studying susceptibility gene polymorphisms can lead to a better understanding of the pathogenesis of DKD and could help prevent this disease or improve its outcomes.

Diabetic kidney disease: Are the reported associations with single-nucleotide polymorphisms disease-specific?

BACKGROUND

The genetic backgrounds of diabetic kidney disease (DKD) and end-stage kidney disease (ESKD) have not been fully elucidated.

AIM

To examine the individual and cumulative effects of single-nucleotide polymorphisms (SNPs) previously associated with DKD on the risk for ESKD of diabetic etiology and to determine if any associations observed were specific for DKD.

METHODS

Fourteen SNPs were genotyped in hemodialyzed 136 patients with diabetic ESKD (DKD group) and 121 patients with non-diabetic ESKD (NDKD group). Patients were also re-classified on the basis of the primary cause of chronic kidney disease (CKD). The distribution of alleles was compared between diabetic and non-diabetic groups as well as between different sub-phenotypes. The weighted multilocus genetic risk score (GRS) was calculated to estimate the cumulative risk conferred by all SNPs. The GRS distribution was then compared between the DKD and NDKD groups as well as in the groups according to the primary cause of CKD.

RESULTS

One SNP (rs841853; SLC2A1) showed a nominal association with DKD (P = 0.048; P > 0.05 after Bonferroni correction). The GRS was higher in the DKD group (0.615 ± 0.260) than in the NDKD group (0.590 ± 0.253), but the difference was not significant (P = 0.46). The analysis of associations between GRS and individual factors did not show any significant correlation. However, the GRS was significantly higher in patients with glomerular disease than in those with tubulointerstitial disease (P = 0.014) and in those with a combined group (tubulointerstitial, vascular, and cystic and congenital disease) (P = 0.018).

CONCLUSION

Our results suggest that selected SNPs that were previously associated with DKD may not be specific for DKD and may confer risk for CKD of different etiology, particularly those affecting renal glomeruli.

Common genetic variants and pathways in diabetes and associated complications and vulnerability of populations with different ethnic origins

Diabetes mellitus is a complex and heterogeneous metabolic disorder which is often pre- or post-existent with complications such as cardiovascular disease, hypertension, inflammation, chronic kidney disease, diabetic retino- and nephropathies. However, the frequencies of these co-morbidities vary among individuals and across populations. It is, therefore, not unlikely that certain genetic variants might commonly contribute to these conditions. Here, we identified four single nucleotide polymorphisms (rs5186, rs1800795, rs1799983 and rs1800629 in AGTR1, IL6, NOS3 and TNFA genes, respectively) to be commonly associated with each of these conditions. We explored their possible interplay in diabetes and associated complications. The variant allele and haplotype frequencies at these polymorphic loci vary among different super-populations (African, European, admixed Americans, South and East Asians). The variant alleles are particularly highly prevalent in different European and admixed American populations. Differential distribution of these variants in different ethnic groups suggests that certain drugs might be more effective in selective populations rather than all. Therefore, population specific genetic architectures should be considered before considering a drug for these conditions.

Angiotensinogen Gene Missense Polymorphisms (rs699 and rs4762): The Association of End-Stage Renal Failure Risk with Type 2 Diabetes and Hypertension in Egyptians

Type 2 diabetes mellitus (T2DM) and hypertension are common chronic diseases mainly associated with the development and progression of end-stage renal disease (ESRD) leading to morbidity and mortality. Gene polymorphisms linked to the renin–angiotensin (AGT)–aldosterone system (RAAS) were broadly inspected in patients with diabetic nephropathy (DN) and hypertension. This study aimed to investigate the association of AGT gene polymorphisms (rs699 and rs4762) with ESRD in T2DM hypertensive Egyptian patients. Genotyping of rs699 and rs4762 was conducted using the tetra-primers amplification refractory mutation system (ARMS-PCR). The allelic distribution analysis was performed on 103 healthy control subjects, 97 non-ESRD patients, and 104 patients with ESRD. The allelic frequencies of AGT gene polymorphisms (rs4762 and rs699) in all study participants were assessed. For the non-ESRD group, the frequencies of the alleles of AGT-rs4762 (χ² = 31.88, p < 0.001, OR = 5.17, CI 95%: 2.81–9.51) and AGT-rs699 (χ² = 4.85, p = 0.027, OR = 1.56, CI 95%: 1.05–2.33) were significantly associated with the non-ESRD group. However, for the ESRD group, the T allele was significantly higher than that in the controls (χ² = 24.97, p < 0.001, odds ratio (OR) = 4.35, CI 95%: 2.36–8.02). Moreover, AGT (rs699) genotypes showed no significant difference between the ESRD group and controls. In conclusion, AGT gene polymorphisms rs699 and rs4762 were associated with non-ESRD versus controls, without any significant risk observed in all patient groups. However, the AGT (rs4762) variant showed a significant risk in the ESRD group in comparison to controls in Egyptians.

Renin-Angiotensin-Aldosterone System Gene Polymorphisms and Type 2 Diabetic Nephropathy in Asian Populations: An Updated Meta-analysis

BACKGROUND

The association of polymorphisms in the renin-angiotensin-aldosterone system candidate genes, namely Angiotensin-Converting Enzyme (ACE) Insertion/Deletion (I/D), Angiotensinogen (AGT) M235T and Angiotensin II Receptor Type 1 (AGTR1) A1166C with Diabetic Nephropathy (DN) has been studied for decades.

OBJECTIVE

This meta-analysis aimed to assess the updated pooled effects of these polymorphisms with DN among Asian populations with type 2 diabetes mellitus.

METHODS

The PubMed electronic database was searched without duration filter until August 2017 and the reference list of eligible studies was screened. The association of each polymorphism with DN was examined using odds ratio and its 95% confidence interval based on dominant, recessive and allele models. Subgroup analyses were conducted based on region, DN definition and DM duration.

RESULTS

In the main analysis, the ACE I/D (all models) and AGTR1 A1166C (dominant model) showed a significant association with DN. The main analysis of the AGT M235T polymorphism did not yield significant findings. There were significant subgroup differences and indication of significantly higher odds for DN in terms of DM duration (≥10 years) for ACE I/D (all models), AGT M235T (recessive and allele models) and AGTR1 A1166C (recessive model). Significant subgroup differences were also observed for DN definition (advanced DN group) and region (South Asia) for AGTR1 A1166C (recessive model).

CONCLUSION

In the Asian populations, ACE I/D and AGTR1 A1166C may contribute to DN susceptibility in patients with T2DM by different genetic models. However, the role of AGT M235T needs to be further evaluated.

Association between AGTR1 A1166C polymorphism and the susceptibility to diabetic nephropathy: Evidence from a meta-analysis

BACKGROUND

Diabetic nephropathy (DN) is a common complication in patients with diabetic mellitus (DM). Growing evidences have demonstrated that the polymorphisms of angiotensin II receptor type 1 (AGTR1) showed significant association with DN onset, but no consensus has been achieved yet. Therefore, we performed this meta-analysis to combine the findings of previous researches for a more comprehensive conclusion.

METHODS

Eligible publications were identified through electronic databases. The intensity of the correlation between AGTR1 A1166C polymorphism and DN susceptibility was evaluated through calculating pooled odds ratios (ORs) with their 95% confidence intervals (95% CIs). Heterogeneity among included studies was examined with Q test. When P-value less than .05, significant heterogeneity presented, random-effects model was used to calculate the pooled ORs, otherwise, the fixed-effects model was used. Stratification analyses were also performed based on ethnicity and the type of DM.

RESULTS

Seventeen eligible articles were finally included in the present meta-analysis. The analysis results showed that AGTR1 A1166C polymorphism was significantly related to increased risk of DN under CC versus AA (OR = 1.723, 95% CI = 1.123-2.644), CC + AC versus AA (OR = 1.179, 95% CI = 1.004-1.383), CC versus AA + AC (OR = 1.662, 95% CI = 1.112-2.486), and C versus A (OR = 1.208, 95% CI = 1.044-1.397) genetic models. Additionally, a similar result was also found in Asian and T2DM (type 2 diabetic mellitus) groups after subgroup analyses of ethnicity and DM type.

CONCLUSION

AGTR1 A1166C polymorphism may increase the susceptibility to DN, especially in Asians and T2DM population.

The Susceptibility Genes in Diabetic Nephropathy

Background

Diabetes mellitus (DM) poses a severe threat to global public health. Diabetic nephropathy (DN) is one of the most common complications of diabetes and the leading cause of end-stage renal disease (ESRD). Approximately 30-40% of DM patients in the world progress to ESRD, which emphasizes the effect of genetic factors on DN. Family clustering also supports the important role of hereditary factors in DN and ESRD. Therefore, a large number of genetic studies have been carried out to identify susceptibility genes in different diabetic cohorts. Extensive susceptibility genes of DN and ESRD have not been identified until recently.

Summary and Key Messages

Some of these associated genes function as pivotal regulators in the pathogenesis of DN, such as those related to glycometabolism and lipid metabolism. However, the functions of most of these genes remain unclear. In this article, we review several susceptibility genes according to their genetic functions to make it easier to determine their exact effect on DN and to provide a better understanding of the advancements from genetic studies. However, several challenges associated with investigating the genetic factors of DN still exist. For instance, it is difficult to determine whether these variants affect the expression of the protein they encode or other cytokines. More efforts should be made to determine how these genes influence the progression of DN. In addition, many results could not be replicated among races, suggesting that the association between genetic polymorphisms and DN is race-specific. Therefore, large, well-designed studies involving more relevant variables and ethnic groups and more relevant functional studies are urgently needed. These studies may be beneficial and retard the progression of DN by early intervention, especially for patients who carry certain risk alleles or genotypes.

Associations between angiotensinogen M235T polymorphisms and the risk of diabetic nephropathy: A meta-analysis

AIMS

The aim of the present study was to clarify the potential relationship of angiotensinogen (AGT) M235T polymorphism and diabetic nephropathy (DN) risk.

METHODS

Comprehensive electronic search in Pubmed, Web of Science, EBSCO, Embase, the Cochrane Library and China National Knowledge Infrastructure (CNKI) to find original articles about the association between AGT M235T polymorphism and DN risk published before 27 September 2017. Literature quality assessment was performed with the Newcastle-Ottawa Scale. Heterogeneity across studies was assessed using I² statistics. Random-effects model or Fixed-effects model was used to estimate the odds ratios (ORs) with 95% confidence intervals (CIs). Sensitivity analyses to assess the influence of individual studies on the pooled estimate. Publication bias was investigated using funnel plots and Egger's regression test. Analyses were performed by using Stata 15.0.

RESULTS

Overall, 20 eligible studies involving a total of 3822 cases and 3911 controls were included in our meta-analysis. The results showed that AGT M235T polymorphism significantly increased DN risk in recessive model (T/T versus M/T + M/M: OR = 1.35, 95%CI (1.07-1.69), I² = 63.8%, Z = 2.56, P = 0.010), homozygote model (T/T versus M/M: OR = 1.46, 95%CI (1.11-1.92), I² = 62.4%, Z = 2.69, P = 0.007) and allele model (T versus M: OR = 1.17, 95%CI (1.01-1.35), I² = 72.5%, Z = 2.14, P = 0.032); Subgroup analysis by ethnicity showed that AGT M235T polymorphism significantly increased DN risk in recessive model (T/T versus M/T + M/M: OR = 1.39, 95%CI (1.06-1.81), I² = 66.6%, Z = 2.42, P = 0.016), homozygote model (T/T versus M/M: OR = 1.47, 95%CI (1.08-2.01), I² = 67.7%, Z = 2.47, P = 0.013) and allele model (T versus M: OR = 1.18, 95%CI (1.02-1.37), I² = 69.4%, Z = 2.26, P = 0.024) in Caucasian DM population; Subgroup analysis by clinical subtype of DM also showed that AGT M235T polymorphism significantly increased DN risk in recessive model (T/T versus M/T + M/M: OR = 1.28, 95%CI (1.05-1.57), I² = 21.3%, Z = 2.40, P = 0.016), homozygote model (T/T versus M/M: OR = 1.41, 95%CI (1.04-1.92), I² = 30.2%, Z = 2.23, P = 0.026) and allele model (T versus M: OR = 1.14, 95%CI (1.03-1.28), I² = 35.5%, Z = 2.44, P = 0.015) in type 1 diabetes patients.

CONCLUSION

Our study showed that AGT M235T homozygous mutation significantly increase DN risk in Caucasian DM population and type 1 diabetes patients.

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.

Angiotensinogen (AGT) gene missense polymorphisms (rs699 and rs4762) and diabetic nephropathy in Caucasians with type 2 diabetes mellitus

Gene polymorphisms associated with the renin-angiotensin-aldosterone system (RAAS) have been extensively studied in diabetic nephropathy (DN) patients, due to therapeutic potential of targeting the RAAS and slowing down the disease progression. The aim of our study was to examine the association between angiotensinogen (AGT) gene polymorphisms (rs699 and rs4762) and DN in Caucasians with type 2 diabetes mellitus (T2DM). A total of 651 unrelated Slovenian (Caucasian) T2DM patients were tested for AGT rs699 and rs4762 polymorphisms using a novel fluorescence-based kompetitive allele-specific polymerase chain reaction (KASPar) assay. A study group consisted of 276 T2DM patients with DN, while control group included 375 patients without DN but who have had T2DM for >10 years. For rs699 polymorphism, the frequencies of GG, GA and AA genotypes were 20.6%, 52.2% and 27.2%, respectively in T2DM patients and 23.4%, 48.1% and 28.5%, respectively in controls. The distributions of GG, GA and AA genotypes for rs4762 polymorphism were 73.9%, 23.2% and 2.9%, respectively in T2DM patients and 70.4%, 27.5% and 2.1%, respectively in controls. No significant differences in the allele frequencies were found between T2DM patients and controls for both polymorphisms. AGT rs699 and rs4762 missense polymorphisms are not associated with DN in our subset of Slovenian T2DM patients.

Estimation of the relationship between the polymorphisms of selected genes: ACE, AGTR1, TGFβ1 and GNB3 with the occurrence of primary vesicoureteral reflux

PURPOSE

Etiopathogenesis of VUR is composite and not fully understood. Many data indicate the importance of genetic predisposition. The aim of this study was to establish the relationship of selected polymorphisms: 14094 polymorphism of the ACE, polymorphism rs1800469 of TGFβ-1, rs5443 gene polymorphism of the GNB3 and receptor gene polymorphism rs5186 type 1 AGTR1 with the occurrence of the primary vesicoureteral reflux.

MATERIAL

The study included 190 children: 90 with the primary VUR confirmed with the voiding cystourethrogram and excluded secondary VUR and a control group of 100 children without a history of the diseases of the genitourinary tract.

METHODS

The study was planned in the scheme: "tested case versus control." Genomic DNA was isolated from the leukocytes of peripheral blood samples. The results were statistically analyzed in the Statistica 10 using χ ² test and analysis of the variance Anova.

RESULTS

Any of the four studied polymorphisms showed no difference in the distribution of genotypes between patients with primary vesicoureteral reflux and the control group. In patients with VUR and TT genotype polymorphism rs5443 GNB3 gene, the glomerular filtration rate was significantly higher than in patients with genotype CC or CT.

CONCLUSIONS

(1) No relationship was found between the studied polymorphisms (14094 ACE gene, rs1800469 gene TGFβ1, GNB3 gene rs5443, rs5186 AGTR1 gene) and the occurrence of primary vesicoureteral reflux. (2) TT genotype polymorphism rs5443 GNB3 gene may be a protective factor for the improved renal function in patients with primary vesicoureteral reflux in patients with genotype CC or CT.

AT1R A1166C variants in patients with type 2 diabetes mellitus and diabetic nephropathy

Background: There are inconsistent reports related to the role of angiotensin II type 1 receptor (AT1R) on the risk of type 2 diabetes mellitus (T2DM) and its renal complications.

Objectives: To identify the association between AT1R A1166C variants with the risk of T2DM and also with diabetic nephropathy (DN). Patients and Methods: In a case-control study, the AT1R A1166C polymorphism was detected in 135 T2DM patients with and without DN and in 98 healthy subjects from Western Iran. The genotypes of AT1R A1166C polymorphism were detected using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

Results: The frequencies of AT1R A1166C genotypes and alleles were not significantly difference between patients with and without DN and controls. The frequencies of rare allele of 1166 C were 10%, 16.5%, 15.9% and 15.3% in micro-, macro- and normo-albuminuric patients and in healthy individuals, respectively ( P > 0.05). The systolic blood pressure and serum creatinine level in DN patients were significantly higher in carriers of AT1R CC compared to carriers of AT1R AA genotype. In the presence of uncontrolled hyperglycemia (HbA1c > 7.5%), there was a trend toward increased risk of macro-albuminuria in carriers of AC+CC genotype (OR=3.66, [95% CI: 0.81-16.58], P = 0.092).

Conclusions: Our study indicated the absence of an association between AT1R A1166C polymorphism with the risk of T2DM and DN. It seems in carriers of AT1R C allele systolic blood pressure and serum creatinine level to be higher compared to the A allele carriers.

Association of AGT M235T gene polymorphism with HSP/HSPN risk

To evaluate the association between angiotensinogen (AGT) gene polymorphism and the risk of Henoch-Schönlein purpura (HSP)/Henoch-Schönlein purpura nephritis (HSPN) we searched the eligible studies through Pub Med, Embase, Cochrane, and China National Knowledge Infrastructure (CNKI) databases according to predefined criteria. A random-effects model was used to calculate the combined odds ratios (ORs) and its corresponding 95% confidence interval (CI). Five studies were recruited for the analysis of the association between AGT M235T gene polymorphism and HSP/HSPN risk. M allele was associated with lower risk of HSP in adult (p = 0.050), TT genotype was associated with the susceptibility to HSP in adult (p = 0.039). AGT M235T gene polymorphism was not associated with HSP risk in children. No marked association was observed between AGT M235T gene polymorphism and HSPN risk. No evidence of publication bias was observed. In conclusion, M allele might be a protective factor against the HSP risk in adult, TT genotype might be a risk factor for the susceptibility to HSP in adult. However, further larger studies should be performed in the future.

Genetic and epigenetic factors influencing chronic kidney disease

Chronic kidney disease (CKD) has become a serious public health problem because of its associated morbidity, premature mortality, and attendant healthcare costs. The rising number of persons with CKD is linked with the aging population structure and an increased prevalence of diabetes, hypertension, and obesity. There is an inherited risk associated with developing CKD, as evidenced by familial clustering and differing prevalence rates across ethnic groups. Previous studies to determine the inherited risk factors for CKD rarely identified genetic variants that were robustly replicated. However, improvements in genotyping technologies and analytic methods are now helping to identify promising genetic loci aided by international collaboration and multiconsortia efforts. More recently, epigenetic modifications have been proposed to play a role in both the inherited susceptibility to CKD and, importantly, to explain how the environment dynamically interacts with the genome to alter an individual's disease risk. Genome-wide, epigenome-wide, and whole transcriptome studies have been performed, and optimal approaches for integrative analysis are being developed. This review summarizes recent research and the current status of genetic and epigenetic risk factors influencing CKD using population-based information.

The role of genetic polymorphisms of the Renin-Angiotensin System in renal diseases: A meta-analysis

Renal failure has a complex phenotype resulting from an underlying kidney disease as well as environmental and genetic factors. In the present study we performed a systematic review and meta-analyses to evaluate the association of the A1166C polymorphism of Angiotensin II type 1 Receptor gene (AGTR1) with Chronic Kidney Disease (CKD), End Stage Renal Disease (ESRD), IgA Nephropathy (IgAN) and Vesicoureteral Reflux (VUR) as well as the association of A1332G polymorphism of Angiotensin II type 2 Receptor (AGTR2) gene with Vesicoureteral Reflux (VUR). We found that neither AGTR1 Α1166C, nor AGTR2 A1332G polymorphisms were significantly associated with any of the aforementioned renal diseases, suggesting that they cannot be used as predictive markers in either general or subgroup ethnic populations.

Genetic and epigenetic risk factors for diabetic kidney disease

Diabetes is increasing at daunting rates worldwide, and approximately 40% of affected individuals will develop kidney complications. Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease, and there are significant healthcare costs providing appropriate renal replacement therapies to affected individuals. For several decades, investigators have sought to discover inherited risk factors and biomarkers for DKD. In recent years, advances in high-throughput laboratory techniques and computational analyses, coupled with the establishment of multicenter consortia, have helped to identify genetic loci that are replicated across multiple populations. Several genome-wide association studies (GWAS) have been conducted for DKD with further meta-analysis of GWAS and comprehensive "single gene" meta-analyses now published. Despite these efforts, much of the inherited predisposition to DKD remains unexplained. Meta-analyses and integrated-omics pathway studies are being used to help elucidate underlying genetic risks. Epigenetic phenomena are increasingly recognized as important drivers of disease risk, and several epigenome-wide association studies have now been completed. This review describes key findings and ongoing genetic and epigenetic initiatives for DKD.

Association of megsin 2093C/T, 2180C/T and C25663G gene polymorphism with the risk of IgA nephropathy

The association between megsin 2093C/T, 2180C/T and C25663G gene polymorphisms and IgA nephropathy (IgAN) risk remains unclear. We aimed to evaluate the association between megsin 2093C/T, 2180C/T and C25663G gene polymorphisms and IgAN risk by performing a meta-analysis. Eligible studies were searched according to predefined criteria by using electronic databases. Six articles were identified for the analysis of the association between megsin 2093C/T, 2180C/T and C25663G gene polymorphisms and IgAN risk. 2093C/T C allele was associated with IgAN risk in overall populations and Asians (overall populations: p = 0.014, Asians: p = 0.037). 2093C/T CC/TT genotype was not associated with IgAN risk in overall populations, Caucasians and Asians. 2180C/T C allele was correlated with IgAN risk in Caucasians (p = 0.024). 2180C/T CC/TT genotype was not associated with IgAN risk in overall populations, Caucasians and Asians. C25663G gene polymorphism was not associated with IgAN onset in Asians. In conclusion, megsin 2093C/T C allele may be genetic marker for IgAN susceptibility in overall populations and Asians. 2180C/T C allele may be risk factor for IgAN onset in Caucasians. However, more studies should be performed in the future.

Lack of association of angiotensin II type 1 receptor A1166C gene polymorphism with the risk of end-stage renal disease

The association between angiotensin II type 1 receptor (AT1R) A 1166C (rs5186) gene polymorphism and end-stage renal disease (ESRD) risk remains controversial. We aimed to assess the association between AT1R A1166C gene polymorphism and ESRD susceptibility by performing a meta-analysis. Eligible studies were searched according to a predefined criterion using electronic databases. Eight articles were identified for the analysis of the association between AT1R A1166C gene polymorphism and ESRD risk. A allele and AA genotype were not associated with ESRD risk in overall populations, Caucasians and Asians (overall populations: p = 0.834 and 0.832, Caucasians: p = 0.853 and 0.884, Asians: p = 0.243 and 0.982). CC and AC genotype were not associated with ESRD risk in overall populations, Caucasians and Asians (overall populations: p = 0.304 and 0.712, Caucasians: p = 0.510 and 0.987, Asians: p = 0.319 and 0.225). In conclusion, AT1R A1166C gene polymorphism may not be correlated with ESRD risk in overall populations, Caucasians and Asians. However, more studies should be performed in the future.

[Advances of genetics in diabetic nephropathy]

Diabetic nephropathy (DN) is one of the most serious chronic complications of diabetes mellitus. The observed incidence patterns in different ethnics and familial clustering have suggested that the genetic factor plays an important role in the development and progression of DN. This paper reviews the recent advances on genetics of DN, including candidate genes association studies, linkage studies and genome-wide association studies (GWASs). Candidate genes association studies and meta-analysis showed that a few candidate genes have been reproducibly associated with DN, such as ACE, AGT and PPARG genes. Linkage studies and genome-wide linkage studies have also identified susceptibility chromosomal loci. With the development of high-throughput sequencing and chip techniques, GWAS has become an important strategy to identify variants responsible for DN. The genetic factor has been the significant contribution to the pathobiology of DN. However, it is not the only cause of the pathobiology of DN, because the environment factor also influences the pathobiology of DN. Nonetheless, genetic studies may provide valuable information for the pathobiology of nephropathy and potential targets of its treatment.

Influence of renin angiotensin system gene polymorphisms on visit-to-visit blood pressure variability in hypertensive patients

BACKGROUND

Visit-to-visit blood pressure (BP) variability has been reported to be a major risk for cardiovascular events. Renin angiotensin system (RAS) gene polymorphisms are reportedly genetic risk factors for cardiovascular diseases and arterial stiffness. In this study, we aimed to reveal the relationship between visit-to-visit BP variability and RAS gene polymorphisms.

METHODS

Study subjects included 427 essential hypertension patients from the Non-Invasive Atherosclerotic Evaluation in Hypertension study cohort, whose BP was measured during at least six outpatient visits. We analyzed the correlation between visit-to-visit variability in systolic BP (SBP) and RAS gene polymorphisms.

RESULTS

We identified angiotensinogen M235T, angiotensin II type 1 receptor A1166C, and angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphisms. Only ACE I/D polymorphisms were correlated with variability in diastolic BP; no gene polymorphisms were correlated with variability in SBP.

CONCLUSIONS

RAS gene polymorphisms, especially ACE I/D polymorphisms, might genetically influence the visit-to-visit BP variability in hypertensive patients.

ACACβ gene (rs2268388) and AGTR1 gene (rs5186) polymorphism and the risk of nephropathy in Asian Indian patients with type 2 diabetes

Patients with type 2 diabetes (T2DM) are usually obese and concurrent obesity results into activation of the renin-angiotensin-system (RAS) which is a risk factor for diabetic nephropathy (DN). Gene-gene interaction between acetyl-coenzymeA carboxylase beta (ACACβ) gene, which is involved in fatty acid metabolism and angiotensin II receptors (AGTR1) gene, which mediates RAS proteins actions on renal tissue, polymorphism with DN have not been studied earlier. The present study was designed with the aim to examine the association of an ACACβ (rs2268388) and AGTR1 (rs5186) gene polymorphism with the risk of DN in Asian Indians. 1,158 patients with T2DM belonging to two independently ascertained North Indian and one South Indian cohorts were genotyped for ACACβ (rs2268388) and AGTR1 (rs5186) polymorphism using real time PCR-based Taq-man assay and PCR-RFLP assays. In all the three cohorts, a significantly higher frequency of T allele and TT genotypes of ACACβ and C allele and CC genotypes of AGTR1 were found in patients with DN as compared to patients without nephropathy. Further, T allele of ACACβ and C allele of AGTR1 were found to be significantly associated with proteinuria, a hallmark of DN. We also found significant epistatic interactions between these two genes. TT genotypes of ACACβ gene and CC genotype of AGTR1 gene confers the risk of DN and both genes had significant epistatic interaction in Asian Indian patients with T2DM.

Association of angiotensinogen M235T gene polymorphism with end-stage renal disease risk: a meta-analysis

Association between angiotensinogen (AGT) M235T gene polymorphism and end-stage renal disease (ESRD) risk is still controversial. This meta-analysis was performed to evaluate the association of AGT M235T gene polymorphism with ESRD susceptibility. A predefined literature search and selection of eligible relevant studies were performed to collect data from electronic databases of PubMed, Embase and Cochrane Library. Sixteen literatures were identified for the analysis of association of AGT M235T gene polymorphism with ESRD risk. T allele and TT genotype were associated with ESRD susceptibility in Caucasians (T: OR = 1.13, 95 % CI: 1.02-1.25, P = 0.02; TT: OR = 1.22, 95 % CI: 1.03-1.45, P = 0.02). However, MM genotype might not play a protective role against ESRD risk in Caucasians. Furthermore, there was no a markedly positive association between AGT M235T gene polymorphism and ESRD susceptibility in overall populations, Asians and Africans. In conclusion, T allele or TT homozygote is associated with the onset of ESRD in Caucasians. However, more studies should be performed in the future.