No association of converting enzyme insertion/deletion polymorphism with immunoglobulin A glomerulonephritis

The Influence of ACE Insertion/Deletion Gene Polymorphism on the Risk of IgA Nephropathy: A Debatable Topic

Background

The connection between angiotensin-converting enzyme insertion/deletion (ACE I/D) gene polymorphisms and IgA nephropathy (IgAN) was conflicting. This pooled analysis was performed to explore this issue.

Methods

All eligible investigations were identified from various electronic databases, and the pooled analysis was evaluated using Stata software.

Results

27 studies with 2538 IgAN cases and 3592 controls were included. In overall subjects, ACE D allele, DD, and II genotype were associated with IgAN susceptibility (D vs. I: OR = 1.21, 95% CI: 1.10–1.32, P < 0.001; DD vs. ID + II: OR = 1.38, 95% CI: 1.20–1.60, P < 0.001; and II vs. DD + ID: OR = 0.83, 95% CI: 0.73–0.95, P=0.007). In Asian and Chinese patients, ACE I/D gene polymorphism was also correlated with IgAN vulnerability. Moreover, ACE D allele, DD, and II genotype were correlated with the progression of IgAN (D vs. I: OR = 1.37, 95% CI: 1.09–1.73, P=0.008; DD vs. ID + II: OR = 1.57, 95% CI: 1.06–2.31, P=0.024; and II vs. DD + ID: OR = 0.69, 95% CI: 0.49–0.99, P=0.045). Conversely, in Caucasian subjects, there was no link between ACE I/D gene polymorphism and the risk of IgAN.

Conclusion

ACE I/D gene polymorphism was correlated with the vulnerability and progression of IgAN in Asian and Chinese patients, and ACE D allele and DD homozygote genotype could be adverse factors for IgAN, while the II homozygote genotype could be an advantage factor. But, no significant association was found between ACE I/D gene polymorphism and IgAN in Caucasians.

M235T polymorphism in the AGT gene and A/G(I8-83) substitution in the REN gene correlate with end-stage renal disease

BACKGROUND/AIMS

This study aimed at investigating if M235T polymorphism in the AGT gene and A/G(I8-83) polymorphism in the REN gene correlate with end-stage renal disease (ESRD).

METHODS

We analyzed 173 ESRD patients and 329 individuals with normal kidney function for differences in the genotype distribution of AGT-M235T and REN-A/G(I8-83) polymorphisms between the two groups. The data for cases and controls were compared using the χ(2) test.

RESULTS

We found significantly higher levels of serum creatinine and CRP in cases in comparison to controls (p < 0.0001). Data comparison showed a significant association of AGT M235T substitution with ESRD in the dominant model (p = 0.008) and in the comparison of the heterozygous substitution with the homozygous common genotype (p = 0.005). Similarly, REN A/G(I8-83) polymorphism showed a significant difference in the distribution of genotypes between cases and controls (p < 0.038) such that a heterozygous substitution was significantly more common in the ESRD cases in comparison to the homozygous common genotype (p = 0.023).

CONCLUSION

We conclude that heterozygous substitutions at the AGT M235T and REN A/G(I8-83) loci correlate significantly with ESRD in a north Indian population.

Association between angiotensin-converting enzyme insertion/deletion gene polymorphism and end-stage renal disease susceptibility

BACKGROUND AND OBJECTIVE

The association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism and end-stage renal disease (ESRD) risk is still controversial. A meta-analysis was performed to evaluate the association between ACE I/D gene polymorphism and ESRD susceptibility.

METHOD

A predefined literature search and selection of eligible relevant studies were performed to collect data from electronic databases.

RESULTS

Thirty-four articles were identified for the analysis of an association between ACE I/D gene polymorphism and ESRD risk. Both D allele and DD genotype were associated with ESRD susceptibility in overall populations (D: OR = 1.20, 95% CI: 1.06-1.36, p = 0.003, DD: OR = 1.47, 95% CI: 1.20-1.78, p = 0.0001) and in East Asians (D: OR = 1.34, 95% CI: 1.06-1.69, p = 0.01, DD: OR = 2.01, 95% CI: 1.29-3.12, p = 0.002). Only the DD genotype had a positive association with ESRD susceptibility in Caucasians (OR = 1.20, 95% CI: 1.01-1.43, p = 0.03). The result from sensitivity analysis in overall populations or Caucasians was similar to those in non-sensitivity analysis, but not among East Asians.

CONCLUSIONS

The results of our study support the idea that D allele or DD genotype was associated with increased risk of ESRD susceptibility in the overall populations, and DD genotype was associated with ESRD susceptibility in Caucasians.

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.

A meta-analysis of the association between angiotensin-converting enzyme insertion/deletion gene polymorphism and end-stage renal disease risk in IgA nephropathy patients

BACKGROUND AND OBJECTIVE

The association between angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene polymorphism and end-stage renal disease (ESRD) risk in IgA nephropathy (IgAN) patients is still controversial. A meta-analysis was performed to evaluate the association between ACE I/D gene polymorphism and ESRD susceptibility in IgAN patients.

METHOD

A predefined literature search and selection of eligible relevant studies were performed to collect data from electronic databases.

RESULTS

Thirteen articles were identified for the analysis of the association between ACE I/D gene polymorphism and ESRD risk in IgAN patients. D allele and DD genotype were associated with ESRD susceptibility in IgAN patients for overall populations (p=0.01 and 0.003, respectively). In Asians, there was a markedly positive association between DD genotype and ESRD susceptibility (p=0.03). Furthermore, D allele and DD genotype were associated with ESRD susceptibility in Caucasians (p=0.02 and 0.03, respectively). However, II genotype might not play a protective role against ESRD onset for overall populations, Asians and Caucasians.

CONCLUSION

DD homozygote is a significant genetic molecular marker for the onset of ESRD in IgAN patients.

Association between ACE polymorphism and risk of IgA nephropathy: a meta-analysis

BACKGROUND

and objective: The effect of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism on risk or progression of immunoglobulin A nephropathy (IgAN) is still debated.Therefore, a meta-analysis was performed to evaluate the association of ACE gene polymorphism with IgAN in different ethnic groups.

METHOD

A predefined search strategy was performed to collect data from electronic databases.

RESULTS

Twenty articles were identified for the analysis of the relationship between ACE polymorphism and IgAN risk, including 11 in Asians and nine in Caucasians. There was a markedly positive association between the D allele or DD genotype and IgAN risk in Asians (OR = 1.27, p = 0.006; OR = 1.83, p < 0.0001). However, a link between D allele or DD genotype and IgAN risk was not found in Caucasians (OR = 1.04, p = 0.46; OR = 1.13, p = 0.12). Ten investigations were included for analysis of the association of ACE polymorphism with IgAN progression, including six in Asians and four in Caucasians. These data did not support a link between the ACE D allele or DD genotype and IgAN progression in Asians and Caucasians (Asians: D: OR = 1.03, p = 0.80; DD: OR = 1.43, p = 0.16; Caucasians: D: OR = 1.29, p = 0.22; DD: OR = 1.31, p = 0.17).

CONCLUSIONS

The D allele or DD genotype is associated with IgAN risk in Asian, but not in Caucasian populations; there was no significant association between the D allele or DD gene and IgAN progression for Asians and Caucasians.

Cardiovascular adaptation, functional capacity and Angiotensin-converting enzyme I/D polymorphism in elite athletes

INTRODUCTION AND OBJECTIVES

Angiotensin-converting enzyme (ACE) is associated with the development of cardiac hypertrophy and improved physical fitness. The objective of this study was to investigate the relationship between the ACE gene insertion/deletion (I/D) polymorphism and adaptation to sports training.

METHODS

The study included 299 elite Spanish athletes (193 men and 106 women) from 32 different sports disciplines, which were grouped according to their static and dynamic components. All participants underwent body composition analysis, Doppler echocardiography at rest, and ergospirometry. Their ACE genotype was determined using the polymerase chain reaction.

RESULTS

The most common genotype in both males and females was the deletion-insertion (DI) heterozygote (57.5% and 54.7%, respectively), followed by the DD homozygote (30.6% and 34.9%), and the II homozygote (11.9% and 10.4%). Differences in morphometric and functional cardiac adaptation were observed between the different sports disciplines, but there was no statistically significant relationship with the ACE I/D polymorphism. Moreover, when athletes with different genotypes were compared, the only differences observed were between the DD and DI groups in female athletes, who differed in body mass index and longitudinal right atrial dimension.

CONCLUSIONS

The ACE I/D polymorphism did not appear to influence cardiovascular adaptation in response to training. However, the DI genotype was the most common, probably because the sample was biased by being made up of elite athletes.

Genetical, histological, and clinical characteristics of IgA-negative mesangioproliferative glomerulopathy

BACKGROUND

Mesangioproliferative glomerulopathy (MesPGN) is a well-defined pathohistological entity. However, the clinical characteristics and prognosis have not been fully established in patients without immunoglobulin (Ig)A (N-IgAN) in contrast to patients with IgA nephropathy (IgAN).

METHODS

A total of 837 consecutive patients underwent renal biopsies. Among them, 465 patients were diagnosed with MesPGN by light microscopy. With immunofluorescent study and electron microscopy (EM), 344 were diagnosed as having IgAN. Among the rest, 84 patients who had no immunofluorescence evidence of IgA and no deposits in EM were defined as N-IgAN. We compared the clinical characteristics, histological findings, and genotypes of the angiotensin-converting enzyme (ACE) gene and plasminogen activator inhibitor-1 gene between IgAN and N-IgAN patients.

RESULTS

Urinary protein excretion and the degree of hematuria were significantly lower in N-IgAN than IgAN patients (0.50 vs. 0.82 g/day; P = 0.01), (1.33 vs. 2.50; P < 0.001, respectively). Creatinine clearance was higher in N-IgAN than IgAN patients (89.4 vs. 74.4 ml/min; P < 0.001). Histopathologically, N-IgAN patients had significantly less advanced glomerular and tubulointerstitial lesions than IgAN patients. Pathological grades in patients with untreated IgAN were more advanced in a time-dependent manner, whereas there was no relationship between histological grades and time of illness in N-IgAN patients. Frequency of the DD genotype of the ACE gene was significantly lower in N-IgAN (DD/ID+II = 8/76) than IgAN (24/90) patients.

CONCLUSIONS

IgA-negative MesPGN is a distinct type of glomerulopathy with a benign renal prognosis. Insertion/deletion polymorphisms of the ACE gene may play some role in the genesis and progression of MesPGN.

Angiotensin-Converting Enzyme Gene Polymorphism Is Correlated to the Progression of Disease in Patients with IgA Nephropathy: A Metaanalysis

Angiotensin-converting enzyme (ACE) displays potent vasoconstrictive effects, attenuation of fibrinolysis, and platelet activation and aggregation. Recently it was mentioned that the insertion/deletion polymorphism of the ACE gene is associated with ESRD. The lengthy course of IgA Nephropathy (IgAN) and the possibility of good outcomes without therapy suggest nontoxic therapies such as ACE inhibitors and angiotensin receptor blockers (ARBs). However, the correlation between the ACE gene polymorphism and progression of IgAN still requires further approval. Here, the author performs a summative analysis on the recent previous reports on the ACE gene polymorphism and its correlation to progression of IgAN. The meta-analysis was performed to assess the correlation between the pattern of ACE gene polymorphism and progression of IgAN. From five available studies, 346 and 555 patients with (group 1) and without (group 2) the progression of disease are evaluated. According to this study, the frequency of DD genotype in group 1 is significant higher than group 2 (p < 0.05). In addition, the author first reports a non-significant correlation between the ethnicity and the ACE gene polymorphism.

Angiotensin-converting enzyme gene insertion/deletion polymorphism in Egyptian patients with myocardial infarction

Introduction. This work aimed to test the association of the angiotensin-converting enzyme gene insertion/deletion (I/D) polymorphism with myocardial infarction.

Subjects and methods. This study comprised 79 Egyptian myocardial infarction cases with a mean age of 54.4±9.9 years including 60 males and 19 females, plus 238 healthy unrelated individuals of nearly matched age and sex as a control group. For all subjects, DNA testing for the angiotensin-converting enzyme gene I/D polymorphism was done using PCR amplification for detection of both the D and I alleles followed by a second run PCR specific for the I allele for samples typed as DD in the first run.

Results. Cases had a higher frequency of DD (29.1%) and ID (62.0%) genotypes than II (8.9%) genotype, with a higher frequency of D allele than I allele (64.4% vs. 33.6%). Compared to controls, cases had a significantly higher frequency of ID genotype (62.0% vs. 47.5%, p<0.05).This was more apparent among cases in the low risk group (p=0.002) than in the high risk group (p=0.041).

Conclusion. The angiotensin-converting enzyme gene I/D polymorphism is probably a risk factor for ischaemic heart disease among Egyptian cases, particularly if integrated with other environmental and genetic risk factors.

Association of angiotensin I-converting enzyme gene insertion/deletion polymorphism and IgA nephropathy: a meta-analysis

BACKGROUND/AIMS

The angiotensin I-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism has been extensively examined for the association with immunoglobulin A (IgA) nephropathy (IgAN), however, conflicting results have occurred. We performed a meta-analysis to evaluate the association of ACE I/D polymorphism with IgAN in different ethnic groups.

METHODS

11 studies testing the association between ACE I/D polymorphism and IgAN susceptibility, and 9 studies testing the association of ACE I/D with IgAN progression were used in this analysis. The overall odds ratio (OR) was estimated by a fixed or random effect model.

RESULTS

The overall OR for the risk of susceptibility and progression of IgAN in Asians for the DD genotype is 2.37 (95% CI 1.04-5.41) and 1.75 (95% CI 1.24-2.56). The overall OR for the D allele in Asians also showed a similar magnitude, though without statistical significance (p = 0.09, p = 0.13, respectively). In Caucasians, both the DD genotype and D allele were associated with IgAN progression (OR 1.90, 1.61, respectively), but not IgAN susceptibility (p = 0.30, p = 0.41, respectively).

CONCLUSION

Our findings support the notion that ACE I/D polymorphism is associated with IgAN. Meanwhile, the role of ACE I/D polymorphism in Asians is different from that of Caucasians.

Renin–angiotensin system gene polymorphisms: association with susceptibility to Henoch–Schonlein purpura and renal involvement

The clinical course of Henoch-Schönlein Purpura (HSP) in children is variable, with some patients having a much more rapidly progressing course than others. We investigated whether polymorphisms of the renin-angiotensin system (RAS) genes are involved in HSP. Three RAS genotypes were examined in 114 children with HSP and in 164 healthy children: the angiotensin I converting enzyme (ACE) insertion/deletion polymorphism, the M235T mutation in the angiotensinogen gene (Agt), and the A1166C in the angiotensin II type I receptor (AT1R) gene. Significant differences were observed between HSP patients and control group in the frequency of ACE and Agt genotypes (p=0.004 and p=0.003, respectively). The TT genotype of Agt gene was associated with a 3.5-fold increased risk for Henoch-Schönlein nephritis (HSN) compared with the MM/MT genotype (odds ratio, 3.5; 95% confidence interval, 1.2-10.4). There was a trend to a higher prevalence of the TT genotype of the Agt gene among patients with nephrotic range proteinuria when compared to the patients with mild proteinuria, although the difference did not reach a statistical significance. The results of this study suggest that polymorphisms of ACE gene and Agt gene likely influence the risk of developing HSP. However, among the three genes of the RAS studies, only Agt gene was associated with the susceptibility to HSN. RAS gene polymorphisms studied are not associated with the presence of nephrotic range proteinuria. Additional studies are warranted to verify the correlation between RAS gene polymorphisms and susceptibility to HSP.

Polymorphism of renin-angiotensin system genes in IgA nephropathy

BACKGROUND AND AIMS

Individuals are prone to disease because of certain disease-susceptible genes. The angiotensin I-converting enzyme (ACE) gene insertion/deletion (I/D), the angiotensinogen (AGT) gene, M235T, and the angiotensin II type 1 receptor (ATR) gene, A1166C, polymorphisms have been associated with IgA nephropathy (IgAN) and its progression. Several studies on Caucasians and Japanese patients have reported contradictory results. We determined these polymorphisms in 118 Chinese patients with IgAN and 94 healthy Chinese subjects to assess their clinical impact.

METHODS

Genotyping was performed with DNA isolated from peripheral leucocytes, polymerase chain reaction amplification of the polymorphic sequence, restriction enzymes digestion, and separation and identification of DNA fragments. Clinical data at renal biopsy and final status on renal function were determined from patients' records.

RESULTS

Comparing all IgAN patients with controls, AGT and ATR genotype distributions were similar, whereas there was a significant increase in the ACE DD genotype (P < 0.05). When comparing patients with end-stage renal failure (IgAN-ESRF) and those without (IgAN-nonESRF), there was no difference among the three gene polymorphisms. In contrast, there were significant differences in higher male prevalence (P < 0.05), increased serum creatinine at presentation (P < 0.05), more sclerosis (P < 0.01) and higher tubulointerstitial lesion score (P < 0.001) in the IgAN-ESRF group.

CONCLUSION

Among the ACE, AGT and ATR gene polymorphisms, only the DD genotype may predispose the individual to IgAN in the Chinese population. None are significant for prognosticating ESRF.

Interaction between ACE and ADD1 gene polymorphisms in the progression of IgA nephropathy in Japanese patients

An interaction effect between the angiotensin-converting enzyme insertion/deletion (ACE I/D) and alpha-adducin (ADD1) Gly460Trp polymorphisms (G460W) on blood pressure regulation has recently been suggested, although its significance in the prognosis of renal function in IgA nephropathy (IgAN) has not been fully investigated. Therefore, we evaluated the clinical manifestations and renal prognosis in 276 Japanese patients with histologically proven IgAN with respect to their ACE I/D and ADD1 G460W polymorphisms. The prognosis of renal function was analyzed by Kaplan-Meier survival curves and multivariate Cox proportional-hazards regression models. Baseline data, including blood pressures, proteinuria, renal function, and incidence of hypertension, were similar for the different genotypes of ACE and ADD1. The individual genotypes taken alone were not associated with the progression of renal dysfunction. However, renal survival of patients with the 460WW polymorphism of ADD1 was significantly worse within the group with the II genotype of ACE (Kaplan-Meier, log rank test; chi2=6.062, P=0.0138) but not for those with other ACE genotypes. In the Cox proportional-hazards regression model with adjustment for clinical risk factors, including hypertension, proteinuria, and no administration of an angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, the 460WW variant of ADD1 was a highly significant and independent risk factor only for patients with the ACE II genotype, with a hazard ratio of 3.65 (P=0.0016), but not for those with other ACE genotypes (hazard ratio=0.65, P=0.2902). These findings suggest an interaction between ACE and ADD1 polymorphisms not only on blood pressure regulation but also on the progression of renal dysfunction in patients with IgAN.

The effect of angiotensin converting enzyme gene polymorphism on chronic allograft dysfunction in living donor renal transplant recipients

BACKGROUND

Chronic allograft dysfunction (CAD), the major cause of the failure of kidney allografts, may be caused by immunological and non-immunological haemodynamic factors. Renin-angiotensin system has been implicated in the development of intraglomerular hypertension and has a central role on progression in chronic renal disease. Polymorphism in 16th intron of the ACE gene has been reported to predict the circulating angiotensin II levels. The aim of this study was to investigate the effect of the both recipient and donor angiotensin converting enzyme (ACE) genotype on the development of CAD in renal allograft recipients.

PATIENTS AND METHODS

A total of 143 renal transplant recipients (95 male, 48 female, mean age 32 +/- 10 yr) were included. In order to exclude the effect of cold ischaemia, only patients transplanted from living donors were selected. Factors analysed in the development of CAD were donor and recipient age, past history of acute rejection, presence of hypertension and hypercholesterolaemia, serum uric acid level and ACE gene polymorphism.

RESULTS

Forty of the patients (28%) had CAD. Homozygous deletion type ACE gene polymorphism was detected in 59 renal transplant recipients (42%) and in 31 donors of the patients (37%). On comparing patients with and without CAD, donor age, rate of acute rejection and hypertension and serum uric acid levels were significantly higher in CAD (+) groups. Neither recipient nor donor ACE genotype was associated with time to CAD. Cox regression analysis revealed donor age (p < 0.001), presence of hypertension (p=0.002) and serum uric acid levels (p=0.009), but neither donor nor recipient ACE genotype as independent factors for predicting development of CAD.

CONCLUSION

Donor age, presence of hypertension and serum uric acid levels was independent factors. Donor and recipient ACE genotype seemed to have no influence on the development of CAD in living donor transplanted patients.

[The involvement of the renin-angiotensin system gene polymorphisms in coronary heart disease]

INTRODUCTION AND OBJECTIVES

Previous studies angiotensin-converting enzyme gene insertion/deletion polymorphism ACE (I/D), angiotensinogen gene polymorphism, and angiotensin II AT1 receptor polymorphism in relation to coronary heart disease controversial results. This study was designed to analyze the association between these gene polymorphisms and the first coronary event in individuals residing on Grand Canary Island, Spain.

PATIENTS AND METHOD

Case-control study. Case subjects (n = 304) were recruited at the first coronary event; age-matched controls (n = 315) were randomly selected from the Grand Canary population. Participants were examined for the usual risk factors. Blood samples were obtained for biochemical analyses and DNA extraction. Genotyping was performed by PCR and restriction analysis.

RESULTS

Neither ACE (I/D) nor AT1 receptor polymorphism was associated with coronary heart disease, whereas the frequency distribution of AGT M235T genotypes among patients and control subjects (TT: 29% and 19%; MT: 48% and 50%; MM: 22% and 31%, respectively) was statistically different (p = 0.003). Multiple logistic regression analysis identified the TT genotype of the angiotensinogen gene (OR = 1.9; 95% CI 1.1-3.4), diabetes (OR = 4.4; 95% CI 2.0-9.4) and hypertension (OR = 2.1; 95% CI 1.3-3.3) as risk factors predicting the coronary event.

CONCLUSIONS

Our results provide no evidence of an association between ACE (I/D) or AT1 receptor polymorphism and coronary heart disease. However, homozygosity for the T allele of the angiotensinogen gene, diabetes and hypertension independently place individuals at higher risk of experiencing a coronary event on Grand Canary Island.

ACE gene polymorphism and IgA nephropathy: an ethnically homogeneous study and a meta-analysis

BACKGROUND

Conflicting results have implicated the angiotensin-converting enzyme (ACE) D allele in the progression of renal damage in patients with IgA nephropathy (IgAN). Most of these findings have been obtained by heterogeneous studies.

METHODS

We investigated the ACE insertion/deletion (I/D) gene polymorphism by polymerase chain reaction (PCR) amplification of genomic DNA in an ethnically homogeneous sample size of IgAN patients from Southern Italy. The association between ACE I/D gene polymorphism and the development of the disease was examined in 247 biopsy-proven IgAN patients and 205 healthy subjects. The association with the progression of renal damage was evaluated in 136 patients with a follow-up of > or =3 years according to the slope of the creatinine clearance against time, and in 221 patients with a follow-up of > or =1 year assessing by univariate and multivariate analyses of renal survival. These associations were further estimated in a meta-analysis of seven studies retrieved in the Medline database. The meta-analysis was performed according to the Mantel-Haenszel-Peto method when homogeneity of the studies was established using the chi(2) test by Breslow-Day.

RESULTS

No difference in the ACE I/D gene distribution between patients and controls and between patients with stable and those with deteriorating renal function was found in our study. A meta-analysis performed separately for Caucasian and Asian studies showed that the ACE I/D gene polymorphism did not contribute to the genetic susceptibility of the development of IgAN (total OR 0.93, 95% CI, 0.71 to 1.23; and 0.95, 95% CI, 0.64 to 1.42, respectively) or the progression of the renal damage (total OR 1.12, 95% CI, 0.67 to 1.88; and 2.26, 95% CI, 0.75 to 6.79, respectively) in both groups.

CONCLUSIONS

Our study and meta-analysis suggest caution in the interpretation of results from association studies enrolling heterogeneous populations. Further studies using new tests, which are free of the bias due to population stratification and ethnicity, are warranted.

Genetic polymorphisms of the renin-angiotensin-aldosterone system in end-stage renal disease

BACKGROUND

Hypertension contributes to the progression to renal failure. A genetic susceptibility to hypertension may predispose to the development of end-stage renal disease (ESRD) and promote a more rapid progression to ESRD in patients with renal diseases. Genes encoding for angiotensinogen (AGT), angiotensin-converting enzyme (ACE), and aldosterone synthase (CYP11B2) are candidates for abnormal blood pressure regulation.

METHODS

Genotyping was performed in 327 control subjects and 260 ESRD patients for the M235T-AGT, the insertion/deletion (I/D)-ACE, and the -344T/C-CYP11B2 gene polymorphisms using polymerase chain reaction, gel analysis, and appropriate restriction digest when required.

RESULTS

Genotype frequencies did not differ significantly between ESRD patients and controls. When ESRD diabetic subjects were compared with diabetic patients without nephropathy, the prevalence of the AGT-MM genotype was lower (28.1 vs. 52.8%, P < 0.01), while the AGT-TT genotype was higher (15.6 vs. 2.7%, P < 0.05). The AGT-TT genotype was associated with a faster progression to ESRD in patients with glomerulonephritis (P < 0.05). In the total ESRD population, progression of renal disease was faster with the ACE-DD than with the DI and II alleles (P < 0.05). This association was particularly strong when the interaction with the AGT genotype was analyzed, with a rapid progression in ACE-DD as compared with ACE-DI and II in patients with the AGT-MM genotype (P < 0.01).

CONCLUSIONS

Susceptibility for ESRD and faster progression to ESRD are linked with the AGT genotype in diabetic patients. Faster progression to ESRD is associated with the ACE genotype when the total population with ESRD and with the AGT genotype when patients with glomerulonephritis are considered. Thus, genes of the renin-angiotensin-aldosterone system are candidate genes for further understanding of the interindividual differences in the development and course of ESRD.

Lack of association of ACE/angiotensinogen genotype with renal function in autosomal dominant polycystic kidney disease

ACE polymorphisms have recently been shown to associate with worse renal and or cardiovascular outcome, with the D allele widely reported as a risk factor for cardiovascular disease. In autosomal dominant polycystic kidney disease (ADPKD), there are conflicting reports of an association between ACE polymorphisms and disease phenotype. There are no previous reports of any association between angiotensinogen polymorphisms and clinical phenotype in ADPKD. We examined the ACE I/D and angiotensinogen M235T polymorphisms in 176 patients with ADPKD. Patients are categorized into three groups according to the reason for initial investigation. Clinical history and examination findings were recorded at the time of first referral. A cohort of 17 patients had progressive renal impairment observed after 3 or more years of follow-up. Reciprocal creatinine against time was plotted in this group. From the patient population of 176, a total of 33 patients reached end-stage renal failure (ESRF) or a serum creatinine greater than 500 microm/liter. ACE genotype and M235T polymorphism frequencies were compared across groups. Serum creatinine and presence of hypertension and onset of ESRF were taken as outcome variables; age and source of referral were taken as confounding variables. There was no association of any genotype or allele with either creatinine, inverse creatinine, hypertension, or age at end-stage renal failure. These findings do not support the proposition that ACE genotype or angiotensinogen polymorphisms are associated with a worse prognosis in patients with ADPKD.

Angiotensin-converting enzyme gene polymorphisms in renal disease: clinically relevant?

The most recent studies of the effect of polymorphisms of the angiotensin-converting enzyme gene on the pathogenesis of renal diseases and the response to treatment with angiotensin-converting enzyme inhibitors continue to produce conflicting results. Large prospective studies are required before angiotensin-converting enzyme genotyping will provide information that will assist in the assessment of prognosis and response to angiotensin-converting enzyme inhibitor treatment in individual patients. Until such studies are performed, all patients with chronic renal disease, regardless of angiotensin-converting enzyme genotype, should be considered candidates for angiotensin-converting enzyme inhibitor therapy.

Polymorphism of angiotensin converting enzyme, angiotensinogen, and angiotensin II type 1 receptor genes and end-stage renal failure in IgA nephropathy: IGARAS--a study of 274 Men

The impact of renin-angiotensin system (RAS) gene polymorphism on the prognosis of IgA nephropathy (IgAN) is still debated. A longitudinal study of renal prognosis in patients with IgAN was conducted to search retrospectively for a genotype-phenotype association between RAS polymorphisms and end-stage renal failure (ESRF). A classification based on serum creatinine (S(cr)) and 24-h proteinuria (24-P) measured at the time of renal biopsy was used to estimate the risk of ESRF in IgAN: stage 1 (S(cr) </= 150 micromol/L and 24-P < 1 g), stage 2 (S(cr) > 150 micromol/L and 24-P < 1 g or S(cr) < or = 150 micromol/L and 24-P > or = 1 g), stage 3 (S(cr) > 150 micromol/L and 24-P > or = 1 g). Deletion/insertion polymorphism (D/I) of the angiotensin I converting enzyme gene, M235T polymorphism (T/M) of the angiotensinogen gene and A1166C polymorphism (C/A) of the angiotensin II type 1 receptor gene were determined in 274 Caucasian men with biopsy-proven IgAN (n = 86, 112, and 76 in stages 1, 2, and 3, respectively). Mean global follow-up was 6 +/- 5 yr after renal biopsy. For stages 1, 2, and 3, ESRF developed in 7 (8. 1%), 39 (34.8%), and 49 (64.4%) cases (P: < 0.0001), 11.7 +/- 4, 5.4 +/- 4, and 2 +/- 2 yr, respectively, after renal biopsy (P: < 0.001). The distributions of the three genotypes into the three stages were similar. Different distributions were observed when patients were grouped by stage and genotype: ID+DD: 72% in stage 1 versus 84.6% in stages 2 + 3 (P: = 0.02; kappa = 0.14); MT+TT: 66.2% in stages 1 + 2 versus 78.9% in stage 3 (P: = 0.04; kappa = 0.09); and AA+AC: 89.9% in stages 1 + 2 versus 97.4% in stage 3 (P: = 0.04; kappa = -0.1). However, with the use of the Cox proportional hazard model, none of the three genotypes was found to have predictive value for renal survival. Compared with S(cr) and 24-P, genotypes DD, TT, and AA are unlikely to serve as clinically useful predictors of ESRF in IgAN.

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.

Insertion/deletion polymorphism in ACE gene is not associated with renal progression in Japanese patients with IgA nephropathy

We determined the relationship between the gene polymorphism of angiotensin I-converting enzyme (ACE) and the progression of immunoglobulin A (IgA) nephropathy in a large cohort in a multicenter trial of ethnically homogeneous Japanese patients (n = 527). Patients with biopsy-proven IgA nephropathy were recruited from several clinics in Japan. The mean observation period was 8.4 +/- 4.7 years. ACE insertion/deletion (I/D) genotype was determined by polymerase chain reaction amplification using allele-specific primers. Clinical factors investigated in all patients were date of birth, sex, levels of urinary protein excretion, duration of observation, serum creatinine (sCr) level, and creatinine clearance (CCr). ACE genotype distribution did not differ between patients who maintained normal renal function (II, 41%; ID, 44.7%; DD, 14.3%) and those who progressed to renal impairment (II, 41.7%; ID, 40.4%; DD, 17.9%). Kaplan-Meier analysis did not show a significant difference in renal survival rate among the three groups of each genotype. In multivariate analysis, only two variables, proteinuria greater than 1.0 g/d of protein and impaired renal function (sCr >1.2 mg/dL or CCr <70 mL/min) at the time of renal biopsy, were found to be risk factors for disease progression leading to a poor outcome. No association was observed between these variables and ACE genotype. It appears that ACE I/D polymorphism may not affect the progressive deterioration of renal function in patients with IgA nephropathy from our multicenter trial.

Evidence for genetic factors in the development and progression of IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is the most common glomerulonephritis in the world among patients undergoing renal biopsy. Once considered a relatively benign condition, longitudinal follow-up studies have revealed that in fact 9 to 50% of patients progress to end-stage renal disease within 20 years of disease onset. In the three decades since its first description by Jean Berger and Nicole Hinglais, clinical, epidemiologic, and immunologic studies of the pathogenesis of primary (idiopathic) mesangial glomerulonephritis with predominant IgA deposits have characterized the features of IgAN as a distinct glomerular disease entity. However, the basic molecular mechanism(s) underlying abnormal IgA deposition in the mesangium with ensuing extracellular matrix expansion and mesangial cell proliferation remains poorly understood. The task of elucidating the molecular basis of IgAN is made especially challenging by the fact that both environmental and genetic components likely contribute to the development and progression of IgAN.

METHODS AND RESULTS

We review here the evidence for genetic factors in the development and progression of IgAN, including a reappraisal of earlier conflicting results from small immunogenetic case-control studies, the evidence for racial differences in the prevalence of IgAN, a detailed summary of all reported occurrences of familial IgAN worldwide, and an exhaustive review of new insights gained through the study of two murine models of hereditary IgAN: the ddY and the uteroglobin-deficient mouse.

CONCLUSIONS

With the development of powerful molecular genetic approaches to the study of both Mendelian and complex human genetic diseases, and the successful efforts of investigators to identify and clinically characterize large IgAN multiplex families, we propose that genetic analysis of familial IgAN is the most promising approach to the identification of IgAN disease/susceptibility genes. Alternatively, if the case-control study design is employed to identify associations between particular candidate genes or markers and the development of IgAN, spurious associations caused by the effects of population stratification should be ruled out by confirming the findings using powerful and sensitive family-based methodologies such as the transmission/dysequilibrium test (TDT).

Angiotensin I-converting enzyme gene polymorphism in non-diabetic renal disease

BACKGROUND

The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene determines the concentration of ACE in serum and local tissues. The role of this polymorphism in progressive chronic renal disease is still not fully clear.

METHODS

We analysed the impact of the D/D polymorphism on the rate of decline in renal function in patients with non-diabetic, chronic progressive renal insufficiency. Seventy non-diabetic patients, aged 21-69 years at baseline, with moderately advanced renal insufficiency due to primary chronic renal disease were followed for an average of 3 years with repeated measurements of their glomerular filtration rate (GFR). Their mean GFR at baseline was 41 ml/min/1.73 m(2) body surface area (BSA). The polymerase chain reaction (PCR) amplification method was used to detect the I/D polymorphism of the ACE gene. GFR was measured as the clearance of (51)Cr-EDTA and the individual rate of progression was calculated using linear regression.

RESULTS

The distributions of the genotypes were: D/D 30%, I/D 49%, and I/I 21%. The rates of progression in the three ACE genotype groups were an annual decline in renal function of -4.2 (SD 4.6) ml/minx1.73 m(2) BSA in the D/D group, -2.7 (SD 3. 4) in the I/D group and -1.7 (SD 3.4) in the I/I group (ANOVA P=0. 12). In patients with proteinuria below 3.5 g/24 h, the D/D group had a significantly higher rate of progression than patients with the I allele. The same was found in a separate analysis when only patients with normal apoliprotein B (below 155 mg/dl) levels were analysed. Furthermore, the D/D genotype was a significant predictor of a more rapid decline in renal function in male, but not female, patients.

CONCLUSION

The results in this study in non-diabetic patients with chronic renal disease indicate that the presence of the D allele in the ACE genotype may be of particular importance as a predictor of a high rate of progression in male patients who otherwise do not have a major burden of documented and important prognostic factors for progressive renal insufficiency.

ACE gene polymorphism and renal responsiveness to ACE inhibitors in IgA nephropathy patients

We examined the renal responsiveness to ACE inhibitor in IgA nephropathy (IgAN) patients according to the grouping of ACE gene polymorphism. Sixty one patients diagnosed as IgAN by renal biopsy and prescribed with ACE inhibitors were enrolled. Genomic DNA was extracted from whole blood and PCR was performed. The I/D polymorphism was determined by the presence of the 287 bp fragment in intron 16 of chromosome 17. During the follow-up period (mean; 44.6 months, median: 44.5 months, 5 to 113 months), the blood pressure of 61 patients was controlled below 130/80 mmHg. The renal responsiveness was determined by the degree of changes of proteinuria at 12 months after initiation of ACE inhibitors and by the slope of reciprocal variation of the serum creatinine against follow-up duration ¿(1/Cr2-1/Cr1)/durations¿. The distribution of the II, ID and DD genotype among 61 patients was 21, 16 and 24 patients, respectively. There were no differences among three genotypes in age, sex, the number of patients with initial blood pressure over 140/90 mmHg, initial serum creatinine level, the number of patients with initial azotemia (> 1.4 mg/dL) and with initial 24-hr proteinuria amount over 2.0 g. Significant anti-proteinuric effect of ACE inhibitor was found in IgAN (p = 0.001), but no significant difference was found among genotypes. Significant difference (p = 0.011) was noticed between II type and DD type in the slope of reciprocal variation of the serum creatinine against follow-up duration. In conclusion, efficacy of ACE inhibitors on renal function preservation in IgAN was more pronounced in DD genotype than II genotype.

The angiotensin-converting enzyme genotype and microalbuminuria in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (AD-PKD) has a variable clinical course. Clinical parameters associated with a worse prognosis are hypertension and proteinuria or microalbuminuria (MA). Because chronic stimulation of the renin-angiotensin system is likely to be present in ADPKD patients, the effect of the angiotensin-converting enzyme insertion/deletion (ACE I/D) genotype on the variability of these clinical parameters was examined in untreated ADPKD patients. Proteinuria and MA were determined in 24-h urine collections. BP measurements were performed with an ambulatory monitor, over 24 h. With analysis of covariance, the ACE genotype was found to be significantly associated with MA, corrected for age, gender, GFR, mean arterial pressure, body surface area, and urinary Na+ excretion (P < 0.05). The patients homozygous for the deletion (DD) had the highest rate of MA (P < 0.05) compared to the patients homozygous for the insertion (II). There was no relationship between the ACE genotype and BP or renal function. A significant positive correlation was found between MA and mean arterial pressure (r = 0.31, P < 0.05), whereas a significant negative correlation was found between MA and renal function (r = -0.28, P < 0.05). In conclusion, in ADPKD patients, MA is partly determined by the ACE I/D polymorphism. Because MA is associated with an enhanced progression toward renal failure, the ACE genotype could help in identifying patients at risk for a worse prognosis.

Angiotensin I-converting enzyme genotype significantly affects progression of IgA glomerulonephritis in an italian population

To evaluate the role of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism in the progression of immunoglobulin A glomerulonephritis (IgA-GN), genotype distribution in 81 biopsy-proven cases of IgA-GN was studied. A logistic regression model showed that the risk for homozygous DD was not significantly elevated in patients with IgA-GN compared with healthy subjects (odds ratio = 1.16; confidence interval [CI], 0.4 to 3.3). However, the 5-year (78% v 90%) and 10-year (52% v 82%) renal survival rates for 47 patients with serum creatine (Cr) levels of 1.5 mg/dL or less at biopsy was significantly less in DD patients (n = 18; chi2 = 5.41; P = 0.02). The hazard ratio (HR) for DD (multivariate analysis from Cox proportional model after adjustment for known factors of progression, such as hypertension [HPT] and proteinuria [PTO]) was 3.07 (CI, 1.1 to 9.4). The HR for heavy PTO was 6.1 (CI, 1.9 to 19). The association of DD genotype with progression was even more striking when patients with other risk factors (heavy proteinuria) were excluded, as shown by DD-related risk in the absence (HR = 3.6; CI, 1.1 to 12) and presence (HR = 2; CI, 0.4 to 10) of PTO. The risk ratio was further increased by the coexistence of DD + PTO (HR = 9.16; CI, 1.8 to 15.7). Furthermore, in a cross-sectional study among patients with IgA-GN, a logistic regression model showed that the risk for homozygous DD was greater, although not at a statistically significant level in the end-stage renal failure subgroup compared with the normal renal function subgroup (odds ratio = 3.16; CI, 0.7 to 13.7) after adjustment by sex, age at biopsy, HPT, PTO, and therapy. Last, DD was significantly more frequent in those patients who started hemodialysis at an earlier age (chi2 for trend = 6.81; P = 0.009). Our study further supports that ACE genotype is a risk factor not for the development, but for the worsening of IgA-GN clinical course. However, on the basis of current knowledge, we cannot exclude that I/D polymorphism may simply serve as a prognostic marker, eventually linked with other discrete loci involved in the progression of renal damage.

IgA nephropathy

Immunoglobulin A nephropathy results from the abnormal deposition of IgA immunoglobulin in the glomerulus, which leads to the characteristic presentation of painless hematuria. It is the most common glomerulonephritis worldwide. Originally described 30 years ago, it was thought to follow a benign course. We now know that IgA nephropathy leads to progressive renal destruction in about one third of affected patients. Alteration in glycosylation of circulating IgA may be an important pathophysiologic mechanism that predisposes to IgA deposition, although how this leads to parenchymal damage remains unclear. Hypertension, high-grade proteinuria, and elevated serum creatinine levels are known risk factors for progressive renal destruction. In addition to these well-recognized risk factors, there appear to be genetic variants, particularly within the angiotensin-converting enzyme gene, that portend a worse outcome.

Angiotensin-converting enzyme gene polymorphism and reversibility of uremic left ventricular hypertrophy following long-term antihypertensive therapy

BACKGROUND

Prolonged antihypertensive therapy might be less effective in reversing the left ventricular hypertrophy (LVH) in uremics bearing the deleted (DD) allele of the angiotensin converting enzyme (ACE) gene than in patients with the inserted (II) allele or in those heterozygous (ID) for the gene.

METHODS

Thirteen DD and 17 II + ID hemodialyzed uremics were followed-up with yearly echocardiography and 24-hour blood pressure (BP) monitoring over five years while on an antihypertensive therapy that included ACE inhibitors as first line drugs.

RESULTS

In the II + ID group there were significant decreases of the left ventricular mass index (LVMi) and of both systolic and diastolic BPs. These changes were less pronounced in the DD group, but the difference was not statistically significant given the wide overlap between the two groups. Further analysis of the data revealed that the only factor associated to a decreased LVMi was the decrease of the systolic BP irrespective of the ACE gene genotype of each individual patient.

CONCLUSIONS

The ACE-gene genotype does not necessarily predict the extent to which LVMi will be lowered by ACE-inhibitors therapy. The LVH of hypertensive uremics is amenable by long-term antihypertensive therapy provided that it results in significantly decreased systolic blood pressure.

Angiotensin converting enzyme gene polymorphisms and renal disease

In the past year there has been a profusion of reports identifying a possible association between the insertion/deletion polymorphism of the angiotensin converting enzyme and renal diseases. Rather than clarifying the situation, it has become more difficult to interpret its significance owing to small sample sizes and concerns over methodology; hence, studies are frequently contradictory. Despite these concerns there is evidence for a role of this polymorphism in progressive renal disease. This review summarizes the major studies in this field and suggests future strategies that might be employed to identify useful genetic markers in nephrology, for which the angiotensin converting enzyme polymorphism has acted as an important paradigm.

The deletion/insertion polymorphism of the angiotensin converting enzyme gene and cardiovascular-renal risk

OBJECTIVE

This meta-analysis attempted to derive pooled estimates for the associations between various cardiovascular-renal disorders and the deletion/insertion (D/I) polymorphism of the angiotensin converting enzyme (ACE) gene.

METHODS

Case-control studies were combined, using the Mantel-Haenszel approach. Joint P values for continuous variables were calculated by Stouffer's method. Continuous measurements reported in different units were expressed on a percentage scale using the within-study mean of the II genotype as the denominator.

RESULTS

The computerized database used for this analysis included 145 reports with an overall sample size of 49 959 subjects. Overall, possession of the D allele was associated with an increased risk of atherosclerotic and renal microvascular complications. In comparison with the II reference group, the excess risk in DD homozygotes (P < 0.001) was 32% for coronary heart disease (CHD; 30 studies), 45% for myocardial infarction (20 studies), 94% for stroke (five studies) and 56% for diabetic nephropathy (11 studies). The corresponding risk in DI heterozygotes amounted to 11% (P= 0.02), 13% (P= 0.02), 22% (P= 0.10) and 40% (P < 0.001), respectively. Hypertension (23 studies), left ventricular hypertrophy (five studies), hypertrophic or dilated cardiomyopathy (eight studies) and diabetic retinopathy (two studies) were not related to the DI polymorphism. Publication bias was observed for CHD, myocardial infarction and microvascular nephropathy, but not hypertension. In studies with DNA amplification in the presence of insertion-specific primers, the risk associated with the DD genotype increased to 150% [95% confidence interval (CI) 76-256; four studies] for diabetic nephropathy, but decreased to 12% (95% CI -3 to 28; seven studies) for CHD and 14% (95% CI -6 to 37; four studies) for myocardial infarction. On the other hand, the pooled odds ratios did not materially change if the meta-analysis was limited to articles published in journals with an impact factor of at least 4. Furthermore, compared with the II control group, the circulating ACE levels (29 studies) were raised 58 and 31% (P < 0.001) in DD and DI subjects, respectively. In contrast, plasma renin (10 studies), systolic and diastolic blood pressure (46 studies) and body mass index (30 studies) were not associated with the D allele.

CONCLUSION

The D allele is not associated with hypertension, but behaves as a marker of atherosclerotic cardiovascular complications and diabetic nephropathy. These associations do not necessarily imply a causal relationship and may have been inflated by publication bias. Nevertheless, their possible therapeutic implications may be subject to further investigation in prospective (intervention) studies.

Association of angiotensinogen gene T235 variant with progression of immunoglobin A nephropathy in Caucasian patients

Genetic variability in the renin-angiotensin system may modify renal responses to injury and disease progression. We examined whether the M235T polymorphism of the angiotensinogen (AGT) gene, the insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene, and the A1166--> C polymorphism of the angiotensin II type 1 receptor gene may be associated with disease progression in 168 Caucasian patients with IgA nephropathy. All patients had serial measurements of their creatinine clearance, proteinuria, and blood pressure (mean+/-SD) with a follow-up of 6.1+/-4.7 yr. The genotype frequencies for each gene were consistent with Hardy-Weinberg equilibrium, and were similar to those of 100 Caucasian control subjects. We examined two primary outcomes: (a) the rate of deterioration of Ccr, and (b) the maximal level of proteinuria. We found that patients with the AGT MT (n = 79) and TT (n = 29) genotypes had a faster rate of deterioration of Ccr than those with the MM (n = 60) genotype (i.e., median values, -6.6 and -6.2 vs. -3. 0 ml/min/yr, respectively; P = 0.01 by Kruskal-Wallis test). Similarly, patients with AGT MT and TT genotypes had higher maximal values of proteinuria than those with the MM genotype (i.e., median values, 2.5 and 3.5 vs. 2.0 g/d, respectively; P < 0.02 by Kruskal-Wallis test). Neither the ACE insertion/deletion nor angiotensin II type I A1166--> C gene polymorphism was associated with disease progression or proteinuria in univariate analysis. Multivariant analysis, however, detected an interaction between the AGT and ACE gene polymorphisms with the presence of ACE/DD polymorphism adversely affecting disease progression only in patients with the AGT/MM genotype (P = 0.008). Neither of these gene polymorphisms was associated with systemic hypertension. Our results suggest that polymorphisms at the AGT and ACE gene loci are important markers for predicting progression to chronic renal failure in Caucasian patients with IgA nephropathy.

Nephropathy of type II diabetes: evidence for hereditary factors?

Family studies point to an important genetic element in the genesis of diabetic nephropathy, but it is not known whether renal abnormalities are present prior to the onset of diabetes. To address this issue we examined all consecutive patients suffering from type II diabetes with a duration of more than 10 years who attended a diabetes outpatient clinic. Ninety-four patients had nephropathy, 307 did not. All offspring who were phenotypically normal (no hypertension, normal oral glucose tolerance, non-smoking) and agreed to participate were examined, 26 from nephropathic and 30 from non-nephropathic diabetic parents. They were compared with 30 offspring matched for age, gender and BMI from non-diabetic parents as controls. We measured urinary albumin excretion under baseline conditions and at several time points after ingestion of 300 g cooked beef and submaximal treadmill exercise, respectively. In addition, casual blood pressure, ambulatory blood pressure, urinary albumin and urinary alpha-1-microglobulin were measured. Primary renal disease was excluded by clinical examination. Under baseline conditions, median urinary albumin excretion rate (AER; microgram/min) was significantly (P < 0.005) higher in offspring of nephropathic type II diabetic patients (7.8; range 1.04 to 19.5) than in the offspring of non-nephropathic type II diabetic patients (4.8; 0.36 to 17.5) and controls (4.4; 0.16 to 18.4). Submaximal treadmill exercise caused a greater proportional increase of AER in offspring of nephropathic type II diabetics (median 16-fold) than in offspring of non-nephropathic diabetic patients (6.3-fold) or controls (4.8-fold). In offspring of nephropathic diabetic patients casual and particularly ambulatory systolic blood pressures were significantly higher, but AER was not correlated with blood pressure. In summary, higher values, albeit within the normal range, for baseline and postexercise albuminuria were noted in phenotypically normal offspring of parents with type II diabetes and nephropathy. The observation suggests that changes in transglomerular albumin traffic are demonstrable prior to the onset of diabetes and diabetic nephropathy in subjects with a potential genetic predisposition to these conditions.

The role of genetic polymorphisms of angiotensin-converting enzyme in the progression of renal diseases

The renin-angiotensin system is likely to be important in the progression of renal diseases because of its effect on tissue hemodynamics and glomerular cell function. Recent evidence from small studies has suggested a possible role for the genetic determinants of angiotensin converting enzyme activity in the rate of progression of renal failure. We studied the effect of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme gene on the rate of renal function deterioration in 822 patients with a variety of renal diseases. We found that the slope of the reciprocal serum creatinine-versus-time plot was steeper in patients homozygous for the deletion allele (DD) compared with those homozygous for the insertion allele (II) (P = .015). When patients with similar renal function at presentation (creatinine < 200 mumol/L) were compared, II homozygotes had significantly improved renal survival (P = .039). Separate analyses of patients with glomerular diseases and tubulointerstitial diseases demonstrated an effect of this genotype in glomerular diseases only. These data provide further evidence of the possible role of the angiotensin-converting enzyme gene in the rate of progression of renal failure, although further studies are required to evaluate the role of this and other proposed candidate genes in renal diseases.