Renin-angiotensin system polymorphisms and renal scarring

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.

Association between angiotensin converting enzyme gene insertion/deletion polymorphism and renal scar risk in children vesicoureteral reflex: a reappraise meta-analysis

Vesicoureteral reflex(VUR) is a common disease in children. Some studies indicated that the angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism associated with the renal scar in VUR, but not all researchers agreed with it. To clarify the effect of ACE I/D polymorphism on renal scar risk in children with VUR, we performed the present meta-analysis. PubMed, CNKI, CBM, and Embase databases were searched for studies that examined the relationship between ACE I/D polymorphism and renal scar risk in children with VUR. The Stata 12.0 software was used for statistical analyses. 11 case-control studies with 1,032 VUR patients were analyzed. The results showed that the DD genotype and D allele were associated with renal scar risk in overall VUR patients, DD vs. DI + II: OR = 1.61, 95% CI = 1.04–2.49, P = 0.03; DD vs. II: OR = 1.78, 95% CI = 1.20–2.65, P < 0.01; D vs. I: OR = 1.38, 95% CI = 1.02–1.86, P = 0.04. Similar results were revealed in Turks, but not in Caucasians and Asians. Our meta-analysis indicated that the ACE DD genotype may increase the risk of renal scar in children with VUR.

Angiotensin Converting Enzyme Gene Insertion/Deletion Polymorphism and Vesicoureteral Reflux in Children: A Meta-Analysis of 14 Case-Control Studies

Vesicoureteral reflux (VUR) is a common and serious urinary disease in children. It usually causes renal scar, urinary tract infection, and chronic renal failure. Previous studies showed the angiotensin converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism might be associated with VUR; however, the conclusions were inconsistent. Therefore we used the meta-analytic approach to clarify the effect of ACE I/D polymorphism on VUR risk.We systematically searched the PubMed, CNKI, and EMBASE databases to identify all the potentially related studies published up to February 4, 2015. Two reviewers independently selected studies and extracted data. The strength of the association was assessed using odd ratio (OR) with its 95% confidence interval (CI) based on fixed or random effects model. The STATA 12.0 software was used for data analysis.A total of 14 case-control studies involving 1197 VUR patients and 1320 healthy controls met the eligibility criteria. Results of meta-analysis showed significant association between ACE I/D polymorphism and VUR risk (D vs. I: OR = 1.28, 95% CI = 1.06-1.54, P = 0.01; DD vs. II: OR = 1.44, 95% CI = 1.12-1.85, P = 0.01; DD vs. DI + II: OR = 1.49, 95% CI = 1.23-1.79, P < 0.01; DD + DI vs. II: OR = 1.20, 95% CI = 0.84-1.72, P = 0.31). Subgroup analyses revealed varied results. In Turkish people, results of all the genetic models other than DI vs. II showed statistical significance; in Caucasians, DD vs. DI + II showed statistical significance; and in Asians, DI versus II showed statistical significance.Our meta-analysis indicated that the ACE I/D polymorphism might be associated with increased risk of VUR in children. However, due to the limitations, we suggest conducting additional studies with larger sample size and adjustment for various risk factors, in the future for further clarification.

Vesicoureteral Reflux, a Scarred kidney, and Minimal Proteinuria: An Unusual Cause of Adult Secondary Hypertension

Hypertension affects about 65 million individuals in the United States. In adult patients, primary aldosteronism and renovascular causes are described as most prevalent. Vesicoureteral reflux as a cause of hypertension, while commonly described in pediatric populations, is less prevalent in the adult population especially in the absence of proteinuria. We present the case of a 31-year-old female presenting with early onset hypertension. Workup for renovascular hypertension was unrevealing. She was found to have right-sided vesicoureteral reflux with a unilateral scarred kidney. Patient underwent a nephrectomy with marked improvement in blood pressure control.

Genetic susceptibility to renal scar formation after urinary tract infection: a systematic review and meta-analysis of candidate gene polymorphisms

Identifying patients who may develop renal scarring after urinary tract infections (UTI) remains challenging, as clinical determinants explain only a portion of individual risk. An additional factor that likely affects risk is individual genetic variability. We searched for peer-reviewed articles from 1980 to December 2009 in electronic databases that reported results showing an association between gene polymorphims and renal scaring after UTI. Two independent researchers screened articles using predetermined criteria. Studies were assessed for methodological quality using an aggregate scoring system. The 18 studies ultimately included in the review had investigated 16 polymorphisms in nine genes in association with renal scarring formation after UTI. Based on the predetermined criteria for assessing the quality of the studies, 12 studies (67%) were identified as being of poor quality design. A meta-analysis of cumulative studies showed on association between renal scarring formation after UTI and the angiotensin converting enzyme insertion/deletion polymorphism [ACE I/D; recessive model for D allele; odds ratio (OR) 1.73, 95% confidence interval (CI) 1.09-2.74, P = 0.02] or transforming growth factor (TGF)-β1 c.-509 T > C polymorphism (dominant model for T allele; OR 2.24, 95% CI 1.34-3.76, P = 0.002). However, heterogeneity among studies was large, indicating a strong difference that cannot only be explained by differences in study design. The studies reviewed in this article support a modest involvement of the vasomotor and inflammatory genes in the development of renal scarring after UTIs. This review also shows that only few possible candidate genes have been investigated for an association with renal scarring, raising the hypothesis that some gene polymorphisms may exert their effects through an interaction with as yet uninvestigated factors that may be related to geographic and/or socio-economic differences.

Genetic risk for recurrent urinary tract infections in humans: a systematic review

Urinary tract infections (UTIs) are a frequent cause of morbidity in children and adults and affect up to 10% of children; its recurrence rate is estimated at 30–40%. UTI may occur in up to 50% of all women in their lifetimes and frequently require medication. Recent advances have suggested that a deregulation of candidate genes in humans may predispose patients to recurrent UTI. The identification of a genetic component of UTI recurrences will make it possible to diagnose at-risk adults and to predict genetic recurrences in their offspring. Six out of 14 genes investigated in humans may be associated with susceptibility to recurrent UTI in humans. In particular, the HSPA1B, CXCR1 & 2, TLR2, TLR4, TGF-β1 genes seem to be associated with an alteration of the host response to UTIs at various levels.

Polymorphisms of the TNF-alpha and ACE genes, and renal scarring in infants with urinary tract infection

PURPOSE

Susceptibility to renal scarring is increasingly investigated through polymorphisms of genes regulating inflammation and fibrosis. TNF-alpha and ACE gene polymorphisms have been studied in chronic renal conditions but their role in urinary tract infection and vesicoureteral reflux associated renal scarring is unclear. We investigated the relationship between TNF-alpha A/G and ACE I/D polymorphisms, and renal scarring after urinary tract infection in infants.

MATERIALS AND METHODS

ACE I/D and TNF-alpha -308 A/G polymorphisms were investigated with restriction fragment length polymorphism analysis in 39 boys and 25 girls with a first urinary tract infection before age 2 years and in 77 controls. Genotype and allele frequencies were compared among children with urinary tract infection with and without renal scarring, and controls.

RESULTS

ACE I/D genotype frequencies were similar among infants with urinary tract infection with and without renal scarring, and controls. However, all 6 children with severe renal scarring and impaired renal function bore a D allele, 5 of which were DD homozygotes. D allele was more common in these severely affected children than in their peers with urinary tract infection and mild or no renal scarring (OR 9.92, 95% CI 1.24-79, p = 0.012), and controls (OR 8.03, 95% CI 1.01-64, p = 0.029). No differences were observed in TNF-alpha A/G genotype frequencies among the 3 groups. Presence of vesicoureteral reflux was not related to phenotypes or allele frequencies.

CONCLUSIONS

Our findings suggest that D allele polymorphism of the ACE gene is associated with urinary tract infection related severe renal scarring in young children.

ACE gene insertion/deletion polymorphism and renal scarring in children with urinary tract infections

Urinary tract infection is a common bacterial disease that presents during childhood and may lead to renal scarring. Several studies have shown a strong association between the angiotensin converting enzyme (ACE) deletion polymorphism and renal scarring in children with vesicoureteric reflux (VUR). The purpose of this study was to investigate the possible correlation between the ACE deletion polymorphism and renal scarring in 186 children with urinary tract infection (UTI), of whom 90 were renal scar positive and 96 were renal scar negative. The control group consisted of 129 children with no UTI. Renal scars were diagnosed by means of (99m)Tc-dimercapto-succinic acid scans, and ACE genotypes were determined as II, ID, and DD by PCR analyses. The ACE genotype distribution was 10% II, 67% ID, and 23% DD in the renal scar-positive group, 18% IotaIota, 42% ID, and 40% DD in the renal scar-negative group, and 22% II, 47% ID, and 31% DD in the control group. No correlation was found between the DD genotype and renal scar formation in children with UTI. The same results were obtained following strafication of the patients by VUR and age of the first urinary tract infection. In conclusion, the results of this study suggest that the DD genotype is not an independent risk factor for renal scarring in children with UTI.

A genome scan in affected sib-pairs with familial vesicoureteral reflux identifies a locus on chromosome 5

The basis for vesicoureteral reflux (VUR) is considered to be primarily genetic, with a 30-50% incidence of VUR in first-degree relatives of patients. The search for the causative gene or genes has been elusive, likely because of VUR being genetically heterogeneous with complex inheritance patterns. In this study, a genome-wide analysis of VUR with high-density single nucleotide polymorphisms was conducted with the aim of identifying susceptibility loci for VUR in 98 families with two or more affected children. Using the affected sib-pair method of analysis in 150 sib-pairs, we identified a genome-wide statistically significant linkage peak with an LOD score greater than 4 on chromosome 5 and two linkage peaks with LOD scores greater than 3.6 on chromosomes 13 and 18 were identified in these 98 families. These results suggested that multiple genes are likely to contribute to the formation of VUR phenotype. Further mapping of these linkage peaks may help identify the causative genes.

Biomarkers for pediatric urological disease

PURPOSE OF REVIEW

New disease-specific biomarkers are sorely needed within all fields of medicine. This review covers the current literature of biomarkers within pediatric urology and discusses future perspectives and directions for biomarker discovery.

RECENT FINDINGS

Biomarkers can be used to diagnose disease, monitor response, or sub-classify disease. Within pediatric urology, numerous markers for renal obstruction [ureteropelvic junction (UPJ)] and vesicoureteral reflux (VUR) have been identified and have shown initial promise; however, no markers have been rigorously validated or demonstrated to be clinically effective. Recent advances in proteomic technologies may provide a new discovery method to identify panels of markers for specific disease.

SUMMARY

New clinically significant biomarkers of UPJ or VUR that can improve the diagnostic capability or help determine risk for renal damage are sorely needed. However, rigorous clinical validation of previously identified markers has been limited. Other studies have demonstrated that combining various markers may help improve the ability to define clinical relevance. To improve biomarker discovery efforts, a combination of focused biomarker studies, potentially using new advanced proteomic technologies, and well designed clinical studies are needed.

Vesicoureteral reflux

Vesicoureteral reflux (VUR), the retrograde flow of urine from the bladder toward the kidney, is common in young children. About 30% of children with urinary tract infections will be diagnosed with VUR after a voiding cystourethrogram. For most, VUR will resolve spontaneously; 20% to 30% will have further infections, but few will experience long-term renal sequelae. Developmentally, VUR arises from disruption of complex signaling pathways and cellular differentiation. These mechanisms are probably genetically programmed but may be influenced by environmental exposures. Phenotypic expression of VUR is variable, ranging from asymptomatic forms to severe renal parenchymal disease and end-stage disease. VUR is often familial but is genetically heterogeneous with variability in mode of inheritance and in which gene, or the number of genes, that are involved. Numerous genetic studies that explore associations with VUR are available. The relative utility of these for understanding the genetics of VUR is often limited because of small sample size, poor methodology, and a diverse spectrum of patients. Much, if not all, of the renal parenchymal damage associated with end-stage disease is likely to be congenital, which limits the opportunity for intervention to familial cases where risk prediction may be available. Management of children with VUR remains controversial because there is no strong supportive evidence that prophylactic antibiotics or surgical intervention improve outcomes. Furthermore, well-designed genetic epidemiological studies focusing on the severe end of the VUR phenotype may help define the causal pathway and identify modifiable or disease predictive factors.

Vesicoureteric reflux deterioration in monozygotic twins

Primary vesicoureteric reflux (VUR) is the most common inherited structural urinary tract disorder, conforming closely to autosomal dominant transmission. A pair of monozygotic siblings is described exhibiting a remarkably parallel clinical course. VUR grade II was diagnosed in girl A during urinary tract infection at the age of 2 yr; screening of her asymptomatic sister (girl B) revealed the same. Renal cortical scintigraphy unveiled unilateral hypo-dysplasia in both the twins. Despite trimethoprime-sulfamethoxazole prophylaxis, infection recurred in girl A after 7 months, while girl B had a first episode 2 months later that prompted regimen switch to nitrofurantoin. Follow-up at the age of 4 depicted bilateral reflux deterioration; an urodynamics study that followed revealed functional bladder instability in both girls and the oral antispasmodic oxybutynin was initiated with good results. Evaluation for reflux should be prompt in infants with urinary infection. Patient siblings display a higher relative reflux risk, being highest in identical twins. Heredity issues, the impact of age and dysfunctional voiding in the clinical course, and the contribution of nuclear medicine in VUR management are discussed.

Polymorphism of the renin-angiotensin-aldosterone system in patients with chronic allograft dysfunction

Polymorphism of the gene encoding components of the renin-angiotensin-aldosterone synthase system (RAAS) represents an area of intense research of cardiovascular disease associations. Numerous studies have addressed the role of RAAS gene polymorphisms in the development and progression of renal disease. Also, it has been reported that patient with ACE (DD) and angiotensinogen AGT (TT) genotypes are associated with chronic allograft dysfunction (CAD). We investigated the effects of gene polymorphisms of the renin-angiotensin-aldosterone system in renal transplant patients (81 males and 50 females; mean age 29.6+/-10.2 years). Genotypes were determined using polymerase chain reaction sequence specific primers and PCR followed by RFLP analysis. Renal allograft recipients with chronic allograft dysfunction had significantly higher frequencies of the MM genotype than those without CAD (P<0.05). The other genetic polymorphisms of the RAAS were not associated with CAD. This study proves that determination of AGT M235T genotype before transplantation may help identify patients who are at risk for chronic renal transplant dysfunction.

Mechanisms of renal damage owing to infection

Urinary tract infection (UTI) is a common bacterial illness in children. It is known to be associated with an increased risk of permanent renal cell damage and scarring which may lead to generation of pathological conditions such as hypertension, pre-eclampsia during pregnancy, renal insufficiency, and end-stage kidney disease. The pathophysiology of renal scarring is still obscure, which makes the prevention of renal damage difficult. During acute infection, there are numerous factors that may contribute to tissue damage. Inflammatory responses are activated by host defense mechanisms as well as by specific bacterial virulence factors. Understanding of these complex mechanisms would be helpful to better identify children at high risk of developing renal scarring following UTI.

Polymorphisms of the angiotensin converting enzyme and angiotensin II type 1 receptor genes and renal scarring in non-uropathic children with recurrent urinary tract infection

AIM

The aim of this study was to investigate whether the angiotensin converting enzyme (ACE) and angiotensin II type 1 receptor (A1166C) gene polymorphisms were associated with the renal scar formation secondary to recurrent urinary tract infection in children without uropathy.

METHODS

The polymorphisms were investigated by polymerase chain reaction in 97 children (81 females, 16 males; age, 2.5-13 years) with recurrent urinary tract infection and 100 healthy controls as a single centre study. Children with vesicoureteral reflux, bladder dysfunction and other uropathies were excluded. The dimercaptosuccinic acid (DMSA) scan performed at least 3 months after a proven urinary tract infection and the result of the last DMSA was taken into consideration.

RESULTS

Renal scarring was found in 30 patients (30.9%) using DMSA scan. The number of urinary tract infection attacks was significantly higher in patients with renal scarring compared with children without scarring (P<0.05). The follow-up period and male/female ratio of patients with or without renal scarring was similar (P>0.05). Age at the first urinary tract infection was lower in the group with scarring. The ACE insertion/deletion genotype distribution and D allele frequency were similar between patients and controls (P>0.05), and in patients with renal scarring and those without renal scarring. Also, the angiotensin II type 1 receptor gene polymorphism was not associated with renal parenchymal damage (P>0.05).

CONCLUSION

The results indicated that the ACE insertion/deletion and angiotensin II type 1 receptor gene polymorphisms were not independent risk factors for renal scar formation in recurrent urinary tract infection of paediatric patients without uropathy.

ACE and AT1 receptor gene polymorphisms and renal scarring in urinary bladder dysfunction

The objective of this study was to investigate whether DNA polymorphisms of the renin-angiotensin system (RAS) genes were associated with renal scar formation in pediatric patients with bladder dysfunction (BD). Although these children are born healthy, due to persistence of immature voiding habits and evolution of BD, some develop progressive renal damage. It has been suggested that the DD genotype of the angiotensin I-converting enzyme (ACE) gene might be an adverse renal prognostic factor. The insertion/deletion (I/D) polymorphism of the ACE gene and the A1166C polymorphism of the angiotensin II type 1 receptor (ATR1) gene were identified by polymerase chain reaction amplification in 42 children with BD (aged 5-14 years) and 198 healthy adult controls. Twelve children had urgency syndrome and 30 had dysfunctional voiding. Renal scarring was found in 16 patients, while 26 patients had normal kidneys on dimercaptosuccinic acid scan. In children with renal lesions there was significant over-representation of the DD genotype compared with either controls or patients without renal damage ( P<0.05). On multivariate analysis, the DD genotype was the only factor that had a significant impact on renal scar formation, introducing a 2.51-fold risk (odds ratio 2.51, 95% confidence interval 1.04-6.04, P=0.04). The A1166C gene polymorphism was not significantly associated with the development of parenchymal damage in children with BD. Our findings introduce ACE I/D gene polymorphism as an independent risk factor for parenchymal destruction in pediatric patients with BD.

Is ACE gene polymorphism a risk factor for renal scarring with low-grade reflux?

The possible relationship between the angiotensin-converting enzyme (ACE) gene insertion/deletion ( I/D) polymorphism and renal scarring secondary to vesicoureteral reflux (VUR) has recently attracted attention and the DD genotype was postulated to be a risk factor for renal scarring. However, available data represent conflicting results. The aim of this study was to investigate the ACE gene I/D polymorphism and the other known risk factors for renal scarring in children with low- and high-grade VUR. The study included 96 (67 females, 29 males) patients (mean age at diagnosis 3.7+/-3.3 years) with VUR that were assessed for ACE I/D gene polymorphism. ACE genotypes were determined as II, ID, and DD using the polymerase chain reaction. The control group consisted of 103 healthy children with the same ethnicity to find the distribution of ACE gene I/D polymorphism in the population. The frequency of renal scarring was 80.8% in the high-grade reflux group and 34.3% in the low-grade reflux group. There was no difference between groups with renal scarring and without scarring with respect to gender, family history of VUR, age at diagnosis of VUR, associated urological abnormalities, frequency of urinary tract infection episodes, and the occurrence of bilateral or unilateral VUR. Genotype DD was found to be a significant risk factor for renal scarring in the study group by multivariate regression analysis (odds ratio 3.79, P=0.011). It was not a risk factor in high-grade reflux patients (odds ratio 0.60, P=0.62). However, it was a risk factor in low-grade patients with respect to renal scarring (odds ratio 4.0, P=0.024). Although renal scarring is not common in low-grade reflux patients, there may be scarring in some patients. DD polymorphism of the ACE gene is a significant risk factor in low-grade reflux patients with renal scarring.

Correction of vesicoureteral reflux: where do we stand?

PURPOSE OF REVIEW

Newer techniques of molecular biology allow us to gain a better understanding of the molecular mechanism of primary urinary reflux. In recent years, diagnostic tools and treatment options for vesicoureteric reflux have dramatically changed. In this review, we want to focus on genetics, molecular biology, histology, clinical findings, diagnostic tools and newer surgical techniques for the treatment of vesicoureteric reflux published between 2003 and March 2004.

RECENT FINDINGS

Recent findings have demonstrated that the renin-angiotensin-aldosterone system does not seem to be responsible for the development of primary vesicoureteric reflux. Echo-enhanced ultrasound with contrast medium in the bladder, performed by an experienced investigator, could replace the voiding cystourethrogram in follow-up studies of patients treated conservatively for vesicoureteric reflux. The sensitivity and specificity of ultrasound is in the range of 70-100% in some studies compared with the standard voiding cystourethrogram. Endoscopic treatment of vesicoureteric reflux using Defux or Macroplastique has gained more and more popularity, with success rates ranging between 60 and 86%. The surgery is performed on an outpatient basis with minimal morbidity. Long-term results after open operative techniques have demonstrated cure of reflux in over 95% of cases.

SUMMARY

In the coming years, echo-enhanced ultrasound may replace the standard voiding cystourethrogram during follow-up and it may be used as an initial test in females with normal voiding patterns. Endoscopic reflux correction must be judged on the re-treatment rates and long-term success.

Renin-angiotensin system polymorphisms in Taiwanese primary vesicoureteral reflux

We studied the angiotensin-converting enzyme (ACE), angiotensinogen (AGT), and angiotensin II type 1 receptor (AT1R) gene polymorphisms for association with susceptibility to primary vesicoureteral reflux (VUR) and disease progression in 74 Taiwanese children, including 16 with end-stage renal disease (ESRD), and 117 normal controls. Polymerase chain reaction-amplified products containing the ACE gene T-5491C, A-5466C, T-3892C, A-3692C, A-240T, Alu I/D, the AGT gene C-532T, G-217A, G-152A, A-20C, A-6G, T174M, T235M, and the AT1R gene A-1138T, T-810A, T-713G, C-521T, AG-214CC, A-153G, A1166C polymorphisms were analyzed by restriction enzyme digestion, gel electrophoresis, or single-strand conformation polymorphism analysis. All the polymorphisms examined were in Hardy-Weinberg equilibrium. The strong non-random association within the ACE, AGT, and AT1R genes suggests low levels of intragenic recombination. None of these polymorphisms showed association with VUR susceptibility. However, the allele frequency distribution of the six ACE polymorphisms among primary VUR patients with or without ESRD was statistically different. The linked ACE T-A-T-A-A-I allele was observed significantly more frequently in VUR children with ESRD (P<0.001). A significant increase of left ventricular mass index was also found in the linked ACE T-A-T-A-A-I allele group compared with the non-ACE T-A-T-A-A-I allele group of patients aged 18 years with renal progression. The AGT A-6G genotype frequencies were significantly different when the analysis was stratified by genotype of the ACE polymorphisms. The data showed that ACE gene polymorphisms were associated with progressive renal deterioration in Taiwanese children with VUR and might act synergistically with the -6 G allele of the AGT gene.