Renin-angiotensin system polymorphisms in Taiwanese primary vesicoureteral reflux

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.

Genotypes of the renin-angiotensin system and glucocorticoid complications

BACKGROUND

Angiotensinogen (AGT) and angiotensin-converting enzyme (ACE) are recognized as important regulators of body mass index (BMI) and systemic blood pressure (BP). An association between these single nucleotide polymorphisms (SNP) of AGT and ACE genes and obesity or hypertension has been established. This study examined relationships between the molecular variants of the AGT and ACE genes and bodyweight or BP in children treated with glucocorticoids for nephrotic syndrome.

METHODS

Twenty Japanese children (male, n = 14; female, n = 6; age, 2-13 years) were genotyped for AGT polymorphisms (M235T and A-6G) and the ACE polymorphisms (insertion/deletion: I/D and rs4341). All of the children studied were treated with daily prednisolone 2 mg/kg for 4 weeks and thereafter alternate-day prednisolone for 8 weeks. BMI, BMI z-scores, blood lipids, renal function and BP in each group were evaluated during the study period.

RESULTS

BMI and BMI z-scores during the glucocorticoid therapy were significantly higher in the TT genotype of the AGT M235T polymorphisms and the AA genotype of the AGT A-6G polymorphisms compared to other genotypes (P < 0.05). In contrast, the molecular variant of ACE I/D and rs4341 genotypes did not change bodyweight during the glucocorticoid exposure. It was evident, however, that the BP and blood lipids and renal function were not significantly influenced by the AGT and ACE polymorphisms.

CONCLUSIONS

The TT genotype of the AGT M235T and the AA genotype of the A-6G polymorphisms may predispose children to bodyweight gain when initially treated with glucocorticoids for nephrotic syndrome.

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

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

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.

Genetics of innate immunity and UTI susceptibility

A functional and well-balanced immune response is required to resist most infections. Slight dysfunctions in innate immunity can turn the 'friendly' host defense into an unpleasant foe and give rise to disease. Beneficial and destructive forces of innate immunity have been discovered in the urinary tract and mechanisms by which they influence the severity of urinary tract infections (UTIs) have been elucidated. By modifying specific aspects of the innate immune response to UTI, genetic variation either exaggerates the severity of acute pyelonephritis to include urosepsis and renal scarring or protects against symptomatic disease by suppressing innate immune signaling, as in asymptomatic bacteriuria (ABU). Different genes are polymorphic in patients prone to acute pyelonephritis or ABU, respectively, and yet discussions of UTI susceptibility in clinical practice still focus mainly on social and behavioral factors or dysfunctional voiding. Is it not time for UTIs to enter the era of molecular medicine? Defining why certain individuals are protected from UTI while others have severe, recurrent infections has long been difficult, but progress is now being made, encouraging new approaches to risk assessment and therapy in this large and important patient group, as well as revealing promising facets of 'good' versus 'bad' inflammation.

Angiotensin II type 1 receptor polymorphisms and susceptibility to hypertension: a HuGE review

The angiotensin II type 1 receptor (AGTR1) plays an integral role in blood pressure control, and is implicated in the pathogenesis of hypertension. Polymorphisms within this gene have been extensively studied in association with hypertension; however, findings are conflicting. To clarify these data, we conducted a systematic review of association studies of AGTR1 polymorphisms and hypertension, and performed a meta-analysis of the rs5186 variant. Results show that the currently available literature is too heterogeneous to draw meaningful conclusions. The definition of hypertension and gender composition of individual studies helps to explain this heterogeneity. Although the structure and splicing pattern of AGTR1 would suggest a likely effect of polymorphisms within the promoter region on gene function, few studies have been conducted thus far. In conclusion, there is insufficient evidence that polymorphisms in the AGTR1 gene are risk factors for hypertension. However, most studies are inadequately powered, and larger well-designed studies of haplotypes are warranted.

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.

Angiotensin-converting enzyme and angiotensin II type 1 receptor gene polymorphisms in children with subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a progressive, debilitating, and fatal brain disorder caused by mutant measles virus infection. Although both viral and host factors seem to be involved in SSPE, the exact pathogenesis remains to be determined. Autoimmune demyelination is characteristic of SSPE. The blood angiotensin-converting enzyme (ACE) activity and angiotensin II (Ang II) levels are associated with the ACE gene polymorphism. Proinflammatory effects of Ang II may contribute to the development of SSPE. The aim of this study was to investigate whether the ACE and Ang II type 1 receptor (AT1R) (A1166C) gene polymorphisms were associated with SSPE. The polymorphisms were investigated by polymerase chain reaction (PCR) in 43 patients with SSPE and 100 healthy controls. The genotype distribution of the SSPE children and healthy controls were as follows: DD 58.1% versus 34.0, ID 37.2% versus 48.0%, and II 4.7% versus 18.0, respectively (P = 0.012). Allele frequencies of patients and controls were D 76.7% versus 58.0%, and I 23.3% versus 42.0%, respectively (P = 0.004). The frequency of DD genotype and D allele were significantly higher in SSPE children compared with controls (P < 0.05). AT1R gene polymorphism distribution was found to be similar in SSPE children and control subjects: AA 55.8% versus 60.7%, AC 37.2% versus 32.1%, and CC 7.0% versus 7.2%, respectively (P > 0.05). In conclusion, the results of this study suggest that the DD genotype of ACE I/D polymorphism may be related to SSPE. Due to small size of this study, further studies with more patients are needed to confirm these results.

Apolipoprotein E, angiotensin-converting enzyme and kallikrein gene polymorphisms and the risk of Alzheimer's disease and vascular dementia

Lipoproteins and vascular factors may play roles in the development of Alzheimer's disease (AD) and/or vascular dementia (VaD). In this study, odd ratios (ORs) and 95% confidence intervals (CIs) for apolipoprotein E (APOE), angiotensin-converting enzyme (ACE), and kallikrein (KLK1) polymorphisms were computed to test their association with the disease by a case-control study. The risk of AD was significantly increased for individuals with APOE varepsilon4 allele (OR = 3.73, 95% CI = 2.38-5.98). The risk of AD was also significant for people with ACE DD genotype, D allele, or T-D haplotype [OR (95% CI) = 4.29 (1.96-10.23), 1.90 (1.35-2.70), or 2.91 (1.71-5.10), respectively]. The above association between ACE-VaD was also strong (p = 0.0012, 0.0050, 0.0007, respectively). Reporter constructs containing the -240 A or T allele displayed similar transcriptional activity in both HEK-293 and IMR-32 cells. Thus, another putative pathogenic marker that is linked with the Alu D allele might affect the risk of AD and VaD in Taiwan.

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.