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.

Association of the angiotensinogen M235T and angiotensin-converting enzyme insertion/deletion gene polymorphisms in Turkish type 2 diabetic patients with and without nephropathy

OBJECTIVE

Recent studies have suggested an association between a deletion variant of the angiotensin-converting enzyme (ACE) gene and diabetic nephropathy. However, this finding has not been confirmed by all investigators. Furthermore, an M235T variant of the angiotensinogen (AGT) gene has been associated with hypertension, an important risk factor for the development and progression of diabetic nephropathy.

RESEARCH DESIGN AND METHODS

We investigated the relationship of the ACE insertion/deletion (I/D) and AGT M235T gene polymorphisms in Turkish patients with type 2 diabetes mellitus (DM) with and without diabetic nephropathy. A total of 102 individuals were screened for the presence of the ACE I/D and AGT M235T polymorphism: 46 individuals who had type 2 DM with diabetic nephropathy and, as controls, 56 individuals who had type 2 DM without diabetic nephropathy. Gene polymorphisms were determined by the specific melting temperature (T(m)) values of the resulting amplicons after real-time online polymerase chain reaction and melting curve analysis.

RESULTS

The frequencies of the ACE DD, ID, and II genotypes were 34.8%, 37.0%, and 28.3%, respectively, among type 2 diabetic patients with nephropathy, and 33.9%, 42.9%, 23.2%, respectively (P=.788), in the control subjects without diabetic nephropathy. On the other hand, the frequencies of the AGT MM, MT, and TT genotypes among the same groups were 26.1%, 52.2%, 21.7% and 26.8%, 57.1%, 16.1%, respectively (P=.758).

CONCLUSIONS

There were no differences in the frequencies of the AGT M235T and ACE I/D genotypes between Turkish patients with type 2 DM with and without nephropathy.

Chronic renal insufficiency among Asian Indians with type 2 diabetes: I. Role of RAAS gene polymorphisms

Background

Renal failure in diabetes is mediated by multiple pathways. Experimental and clinical evidences suggest that renin-angiotensin-aldosterone system (RAAS) has a crucial role in diabetic kidney disease. A relationship between the RAAS genotypes and chronic renal insufficiency (CRI) among type 2 diabetes subjects has therefore been speculated. We investigated the contribution of selected RAAS gene polymorphisms to CRI among type 2 diabetic Asian Indian subjects.

Methods

Twelve single nucleotide polymorphisms (SNPs) from six genes namely-renin (REN), angiotensinogen (ATG), angiotensin converting enzyme I (ACE), angiotensin II type 1 receptor (AT1) and aldosterone synthase (CYP11B2) gene from the RAAS pathway and one from chymase pathway were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and tested for their association with diabetic CRI using a case-control approach. Successive cases presenting to study centres with type 2 diabetes of ≥2 years duration and moderate CRI diagnosed by serum creatinine ≥3 mg/dl after exclusion of non-diabetic causes of CRI (n = 196) were compared with diabetes subjects with no evidence of renal disease (n = 225). Logistic regression analysis was carried out to correlate various clinical parameters with genotypes, and to study pair wise interactions between SNPs of different genes.

Results

Of the 12 SNPs genotyped, Glu53Stop in AGT and A>T (-777) in AT1 genes, were monomorphic and not included for further analysis. We observed a highly significant association of Met235Thr SNP in angiotensinogen gene with CRI (O.R. 2.68, 95%CI: 2.01–3.57 for Thr allele, O.R. 2.94, 95%CI: 1.88–4.59 for Thr/Thr genotype and O.R. 2.68, 95%CI: 1.97–3.64 for ACC haplotype). A significant allelic and genotypic association of T>C (-344) SNP in aldosterone synthase gene (O.R. 1.57, 95%CI: 1.16–2.14 and O.R. 1.81, 95%CI: 1.21–2.71 respectively), and genotypic association of GA genotype of G>A (-1903) in chymase gene (O.R. 2.06, 95%CI: 1.34–3.17) were also observed.

Conclusion

SNPs Met235Thr in angiotensinogen, T>C (-344) in aldosterone synthase, and G>A (-1903) in chymase genes are significantly associated with diabetic chronic renal insufficiency in Indian patients and warrant replication in larger sample sets. Use of such markers for prediction of susceptibility to diabetes specific renal disease in the ethnically Indian population appears promising.

Assessing genetic susceptibility to diabetic nephropathy

Diabetic nephropathy is a serious complication of diabetes and the leading cause of end-stage renal disease. Studies indicate both environmental and genetic factors contribute to the development and progression of diabetic nephropathy. In particular, epidemiological evidence shows a familial clustering of nephropathy in siblings with diabetes, supporting an important role of genetic susceptibility in the pathogenesis of diabetic nephropathy. A common approach in genetic research is assessment of candidate gene polymorphisms using case-control analysis; a number of studies have evaluated predictable candidate genes for diabetic nephropathy. In contrast, only a few studies have used a whole genome approach, such as scanning of micro-satellite markers, in the assessment of genetic susceptibility to diabetic nephropathy. A whole genome linkage analysis using families of Pima Indians showed susceptibility loci for diabetic nephropathy on chromosome 3, 7, and 20. Another linkage analysis using discordant sib-pairs of Caucasian families with type 1 diabetes identified a critical area on chromosome 3q. However, these results have been inconclusive and further investigation is required. Recently, a genome-wide, case-control analysis identifying susceptibility genes for diabetic nephropathy was performed. As a result, a single nucleotide polymorphism in exon 23 of the solute carrier family 12 (sodium-chloride cotransporter) member 3 gene was found to be strongly associated with diabetic nephropathy. Although further assessment of this polymorphism is needed, this strategy offers great promise in the identification of genetic factors predisposing patients to diabetic nephropathy. Identification of genetic susceptibility markers may offer new hope in the diagnosis and treatment of diabetic nephropathy.

Genetic aspects of diabetic nephropathy

BACKGROUND

Diabetic nephropathy from type 2 diabetes mellitus is the most common cause of end-stage renal disease (ESRD) in the United States and in Western Europe. Although patients with overt nephropathy generally experience greater cumulative glycemic exposure, the difference in glycemic control between patients developing nephropathy compared to those who did not, could not be demonstrated. This observation is consistent with the notion that perhaps other factors, in addition to glycemic control, have a bearing on the development of nephropathy. Genetic factors, which specifically increase the susceptibility to nephropathy in patients with diabetes, have been proposed.

METHODS

A range of linkage and association studies has been performed for revealing the genetic background of diabetic nephropathy.

RESULTS

Until now, no mutation has been identified which could explain the development of diabetic nephropathy in the majority of diabetic patients.

CONCLUSIONS

Because of relatively small case numbers of all studies being performed so far, conclusions from those studies are limited. With the development of better technologies for an affordable genome-wide association study using thousands of markers, it might become possible to unravel the genetic causes of diabetic nephropathy.

Genetics of diabetic nephropathy

Diabetic nephropathy can develop in up to one-third of patients with type 1 diabetes and approximately 25% of patients with type 2 diabetes. This complication is important as it not only leads to renal failure but is associated with a high risk of coronary artery disease and other vascular complications. Although hyperglycaemia is necessary for the development of diabetic nephropathy, it is not sufficient, genetic factors also being important. This is evidenced by studies showing that only a subgroup of patients are at risk of nephropathy and that nephropathy clusters in families. The genes involved in susceptibility to diabetic nephropathy have yet to be identified. Most studies to date have been case-control in design, and there have been conflicting results. Genes suggested as having a role include those encoding angiotensin-1 converting enzyme, apolipoprotein E, heparan sulphate and aldose reductase. In order to clarify the role of these and other candidate genes in nephropathy, association studies in families are necessary. Because of the large number required, this will require international collaboration. A genetic marker for nephropathy would enable the earlier detection of this complication, thus facilitating screening and targeted intervention. An understanding of the role of susceptibility genes will ultimately allow the development of novel therapeutic strategies.

Angiotensin I-converting enzyme gene insertion/deletion and angiotensinogen M235T polymorphisms: risk of chronic renal failure. End-Stage Renal Disease Study Group

BACKGROUND

Chronic renal failure (CRF) is a complex phenotype that results from an underlying kidney disease and superimposing environmental and genetic factors. The aim of our study was to evaluate the role of polymorphisms in the genes encoding for components of the renin-angiotensin system (RAS) in the development and/or progression of CRF.

METHODS

Two hundred forty-seven family trios (patients with CRF and both parents; 120 with primary chronic glomerulonephritis, 80 with interstitial nephritis, and 47 with type 1 diabetes with nephropathy) were examined, and transmission/disequilibrium test (TDT) was used to evaluate allele transmission from heterozygous parents to affected offspring.

RESULTS

The D allele of the angiotensin I-converting enzyme (ACE) gene insertion/deletion polymorphism was transmitted significantly more frequently than expected for no association among all examined trios and in the subgroup of patients with interstitial nephritis. The angiotensinogen 235T allele was transmitted significantly more frequently to patients with CRF than expected for no association, but the effect was seen only in patients with interstitial nephritis. The presence of the DD or ID genotype was associated with a faster rate of decline of renal function, which was not observed for the angiotensinogen M235T polymorphism. For chymase gene and angiotensin II receptor type 1 gene, allele transmission did not deviate significantly from a random proportion of 50:50%.

CONCLUSIONS

The results of this study suggest that ACE gene insertion/deletion and angiotensinogen M235T polymorphisms contribute to the increased risk for the development of CRF, but the magnitude of the effect within subsets of patients with specific etiologies of CRF must be evaluated further.

Association of plasminogen activator inhibitor-1 4G/4G genotype and type 2 diabetic nephropathy in Chinese patients

BACKGROUND

Plasminogen activator inhibitor-1 (PAI-1) is a key regulator of fibrinolytic pathway and extracellular matrix (ECM) turnover. Because diabetic nephropathy is characterized by the presence of basement membrane thickening and mesangial expansion, we examined the role of PAI-1 gene polymorphisms in the development of type 2 diabetic nephropathy. Evidence also suggested that the PA/plasmin system and the renin-angiotensin system (RAS) interact together to affect the risk of fibrosis and thrombosis. Hence, we also studied the synergistic effect between PAI-1 and angiotensin-converting enzyme (ACE) gene polymorphisms.

METHODS

The PAI-1 and ACE (D/I) gene polymorphisms were examined in a cohort of Chinese type 2 diabetic patients who had diabetes for an average of 14 years. These patients were sex and age matched. Group A (N = 46) consisted of patients without diabetic nephropathy (normoalbuminuric with creatinine <120 micromol/L), and group B (N = 95) was with diabetic nephropathy (with albuminuria or renal impairment, including patients on dialysis).

RESULTS

Patients with type 2 diabetic nephropathy had a higher frequency of PAI-1 (4G/4G) genotypes than those without nephropathy [4G/4G:4G/5G:5G/5G = 41:38:21 (%) vs. 15:65:20(%), P = 0.005]. Diabetic patients with coexistence of PAI-1 4G/4G genotype and ACE D alleles had a higher incidence of diabetic nephropathy (22 vs. 7%, P = 0.012) than those with other combinations of genotypes. Multivariate logistic regression analysis showed that PAI-1 4G/4G (P = 0.01) and the prevalence of hypertension (P < 0.0001) are independent risk factors of development of type 2 diabetic nephropathy.

CONCLUSIONS

These results suggest that the PAI-1 4G/4G genotype is associated with an increased risk for type 2 diabetic nephropathy in Chinese patients, which is an independent risk factor for the development of nephropathy. The PAI-1 4G/4G genotype also exhibits a synergistic effect with the ACE D allele on development of diabetic nephropathy.

[Possible genetic causes for late complications of diabetes mellitus]

BACKGROUND

Hyperglycemia occurs in every patient with diabetes mellitus. It is the most important factor in the development of diabetic complications. However, the onset, intensity and the progression of complications show large interindividual variations. Manifestation in families and the lack of complications in some diabetics with poor metabolic control indicate a genetic predisposition to develop diabetic complications like nephropathy, neuropathy and angiopathy.

NEPHROPATHY

Diabetic nephropathy occurs only in 25 to 40% of the diabetic patients. Therefore a genetic risk factor for this complication is very likely. Various variations in genes like ACE-gene and angiotensinogen-gene have been described, which could be associated with the development of diabetic nephropathy.

NEUROPATHY

Peripheral diabetic neuropathy occurs in up to 66% of all diabetics. Therefore and because of the possible pathological mechanisms genetic risk factors like variations in the Na/K-ATPase-gene and in the aldose reductase-gene are discussed.

RETINOPATHY

An association between diabetic retinopathy and polymorphisms in the ACE-gene and the aldose reductase-gene seems very unlikely, because up to 75% of the diabetic patients suffer from retinopathy after 15 years of diabetes.

MACROANGIOPATHY

A large number of studies show an association between diabetic macroangiopathy and genetic variations in the ACE-gene (I/D-variant) and the paraoxonase-gene (2 isoforms).

CONCLUSION

Based on the current evidence for associations of genetic markers with diabetic complications, the generation of an individual risk profile based on genetic markers seems to be possible. In addition to near euglycemia genetic markers could direct therapeutic strategies and lead to new therapeutic approaches.

Angiotensinogen T174M and M235T gene polymorphisms are associated with the extent of coronary atherosclerosis

BACKGROUND

The relations of the angiotensinogen (AGT) T174M and M235T gene polymorphisms to the risk of coronary heart disease (CHD) have been investigated in only a few studies with conflicting results.

RESULTS

Therefore, we analysed the relationship of the AGT gene polymorphisms to the presence and extent of CHD in 2250 male Caucasians whose coronary anatomy was defined by means of coronary angiography. The relative frequencies of the T and M alleles of the T174M and of the M235T gene variation did not significantly differ between patients without or with single-, double- or triple-vessel disease and between subjects without or with myocardial infarction (MI). In contrast the mean CHD score--defined by Gensini--was higher within MM homozygotes of the T174M gene variation than within TT genotypes; TM subjects had intermediate values. In M235T genotypes, mean CHD scores were similar in the total sample and in older individuals (> or = 62 years), whereas in younger individuals (< 62 years) a higher CHD score was found within AGT 235 T allele carriers than within MM homozygotes. In younger individuals with high apoAI plasma levels, the mean CHD score was clearly higher within TT homozygotes of the M235T gene variation than within MM genotypes; MT subjects had intermediate values. An interaction between both angiotensinogen gene polymorphisms on the extent of CHD or on the risk of non-fatal MI were not observed when the M allele of AGT T174M was combined either with the T allele or the TT genotype of M235T.

CONCLUSIONS

The present study strengthens the hypothesis of an association of both angiotensinogen gene polymorphisms with the extent of coronary heart disease.

Plasma renin and prorenin and renin gene variation in patients with insulin-dependent diabetes mellitus and nephropathy

BACKGROUND

The most striking abnormality in the renin angiotensin system in diabetic nephropathy (DN) is increased plasma prorenin. Renin is thought to be low or normal in DN. In spite of altered (pro)renin regulation the renin gene has not been studied for contribution to the development of DN.

METHODS

We studied plasma renin, prorenin, and four polymorphic markers of the renin gene in 199 patients with IDDM and DN, and in 192 normoalbuminuric IDDM controls matched for age, sex, and duration of diabetes. Plasma renin and total renin were measured by immunoradiometric assays. Genotyping was PCR-based.

RESULTS

Plasma renin was increased in patients with nephropathy (median (range), 26.3 (5.2-243.3) vs 18.3 (4.2-373.5) microU/ml in the normoalbuminuric group, P<0.0001). Prorenin levels were elevated out of proportion to renin levels in nephropathic patients (789 (88-5481) vs 302 (36-2226) microU/ml, P<0.0001). Proliferative retinopathy had an additive effect on plasma prorenin, but not on renin. DN was associated with a BglI RFLP in the first intron of the renin gene (bb-genotype: n=106 vs 82 in DN and normoalbuminuric patients respectively, P=0.037), but not with three other polymorphisms in the renin gene. A trend for association of higher prorenin levels with the DN-associated allele of this renin polymorphism was observed in a subgroup of patients with DN (bb vs Bb+BB, P=0.07).

CONCLUSIONS

The results indicate that in DN there is an increase in both renin and prorenin levels. A renin gene polymorphism may contribute weakly to DN. Although speculative, one of the renin gene alleles could lead to increased renin gene expression, leading to higher renin and prorenin levels. These may play a role in the pathogenesis of DN.

Association between AGT codon 235 polymorphism and variation in serum concentrations of creatinine and urea in Canadian Oji-Cree

Finding the genetic determinants of intermediate quantitative traits, such as serum creatinine and urea, might aid in finding the determinants of disease phenotypes, such as renal failure, that are, in part, defined according to threshold values imposed upon such traits. We evaluated the association between common variation in the gene encoding angiotensinogen, AGT, and the serum concentrations of creatinine and urea in non-diabetic Canadian Oji-Cree. We determined genotypes of the AGT codon 235 polymorphism among 502 non-diabetic Oji-Cree. We used multivariate analysis of variance to identify significant determinants of variation in serum concentrations of creatinine and urea and of systolic and diastolic blood pressure. We found significant associations between the AGT codon 235 genotype and serum concentrations of creatinine and urea (p = 0.017 and 0.049, respectively) and systolic blood pressure (p = 0.041). Compared with subjects with the other two genotypes, homozygotes for AGT T235/T235 had significantly lower serum concentrations of creatinine and urea and significantly higher mean systolic blood pressure. The findings suggest that the AGT T235 allele is a determinant of intermediate traits related to renal function in these aboriginal Canadians.

Lack of association of angiotensin-converting enzyme (DD/II) and angiotensinogen M235T gene polymorphism with renal function among Chinese patients with type II diabetes

The prevalence of diabetic nephropathy is greater in nonwhite patients with type II diabetes, including the Chinese, and genetic variation appears to have a role. We examined angiotensin-converting enzyme (ACE) DD/II and angiotensinogen (Atg) M235T polymorphism in a cohort of Chinese patients with type II diabetes with an average duration of diabetes of 14 years. Group A (n = 88) did not have significant diabetic nephropathy (creatinine levels </= 130 micromol/L [</=1.48 mg/L], without macroalbuminuria), and group B (n = 80) had significant diabetic nephropathy (macroalbuminuria or creatinine level >130 micromol/L [>1.48 mg/d], and those undergoing dialysis). The two groups were matched in different aspects, including age, duration of diabetes, blood pressure, and glycemic control. The results showed: (1) no difference of genotype distribution between groups A and B (DD:DI:II, 14%:45%:41% v 8%:38%:54%; P = 0.20; TT:TM/MM, 70%:30% v 76%:24%; P = 0.43), (2) no evidence of synergistic effect of ACE (DD/II) and Atg M235T gene polymorphisms, (3) no difference of allele frequencies between groups A and B (D:I, 36%:64% v 27%:73%; P = 0.20 and T:M, 86%:16% v 86%:14%; P = 0.73), and (4) ACE activity was greatest in patients with DD genotype and least in those with II genotype (DD:DI:II = 66. 9 +/- 13.3 U/L:61.5 +/- 19.9 U/L:45.0 +/- 17.0 U/L; P < 0.005). The data do not support a role of ACE (DD/II) or Atg M235T polymorphism in the development of diabetic nephropathy in Chinese patients with type II diabetes, and no synergistic effect was found between them. Greater ACE activity was associated with DD genotype, and its role in diabetic nephropathy remains to be elucidated.

Association between AGT T235 variant and microalbuminuria in Canadian Oji-Cree with type 2 diabetes mellitus

OBJECTIVE

To assess the association between the common variation in the gene encoding angiotensinogen, AGT, and the presence of microalbuminuria in Canadian Oji-Cree with type 2 diabetes mellitus.

RESEARCH DESIGN AND METHODS

We compared the frequencies of the AGT promoter and M235T polymorphisms among three subgroups of adult Oji-Cree: 50 subjects who had type 2 diabetes with microalbuminuria, 6 subjects who had type 2 diabetes without albuminuria and 302 non-diabetic, normotensive subjects.

RESULTS

We found the AGT T235 allele was present at a significantly higher frequency, and that T235/T235 homozygotes were significantly more prevalent, among the subjects who had type 2 diabetes with microalbuminuria than among the subjects in the other two groups.

CONCLUSIONS

The findings suggest that the AGT T235 allele is a determinant of the nephropathy susceptibility related to type 2 diabetes in these aboriginal Canadians.