Angiotensin II type 1 receptor gene A1166C polymorphism and essential hypertension in Chinese: a meta-analysis

The Role of Angiotensin II Type 1 Receptor A1166C Polymorphism in Autosomal Dominant Polycystic Kidney Disease

Introduction Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic disorder that affects the kidney, which affects all ethnical groups worldwide, with varied clinical presentations and severity. The studies done in various parts of the world on the association between angiotensin II type 1 receptor (AT1R) A1166C gene polymorphism and ADPKD patients have revealed inconsistent results. This study was done to assess the role of AT1R A1166C gene polymorphism in ADPKD in the South Indian population, which is the first of its kind. Methodology This is a case-control study, conducted at a tertiary care center in South India. This study was concerned with the frequency of exposure (genotype) in ADPKD patients. Peripheral blood samples from 85 unrelated ADPKD patients and 94 controls without diabetes, hypertension, or any kidney-related disease were collected. The AT1R A1166C polymorphism was compared between (i) the cases and controls, (ii) early and late stages of chronic kidney disease (CKD) (ADPKD) subjects, and (iii) ADPKD subjects with and without hypertension. Results Among the ADPKD patients, 45 (52.9%) subjects showed early stage (CKD stages 1-3), and 40 (47%) subjects showed late stage CKD (CKD stages 4 and 5). The genotype distribution of the studied 85 ADPKD patients was almost similar. No significant association was found between the genotype distribution of AT1R A1166C polymorphism in AA vs. AC (OR = 1.11; 95% CI = 0.37-3.32; p < 0.844) and A vs. C (OR = 1.11; 95% CI = 0.38-3.32; p < 0.847) between cases and controls. The genotype distributions in genetic model AA vs. AC (OR = 3.07; 95% CI = 0.56-16.8; p < 0.177) and allelic model A vs. C (OR = 2.13; 95% CI = 0.40-11.3; p < 0.364) between the early and late CKD stages of ADPKD were also not significant. No significant association of gene polymorphism was found between the non-hypertensive and hypertensive groups of ADPKD. Conclusion The results of our study suggest there is no significant association between AT1R A1166C polymorphisms and ADPKD in the South Indian population. Further, the gene polymorphism is not related to the progression of ADPKD or the presence of hypertension in ADPKD cases in South India.

Association of AGTR1 A1166C and CYP2C9∗3 Gene Polymorphisms with the Antihypertensive Effect of Valsartan

Background

The differences in the antihypertensive treatment with angiotensin type II receptor blockers (ARBs) may be attributed to polymorphisms in genes involving drug-targeted receptor and drug metabolism. The present study aimed to investigate whether the antihypertensive effect of the ARB drug valsartan was associated with angiotensin II type 1 receptor (AGTR1) gene polymorphism (A1166 C) and cytochrome P450 enzyme 2C9 (CYP2C9) gene polymorphism (CYP2C9∗3).

Methods

281 patients with hypertension who received valsartan monotherapy in the past month were included in this retrospective study. Polymerase chain reaction-melting curve analysis was performed to genotype the AGTR1 and CYP2C9 gene polymorphisms. Based on the systolic blood pressure (SBP) and diastolic blood pressure (DBP) at the time of visit, the patients were divided into well-controlled group (n = 144, SBP/DBP <140/90 mmHg) and poorly controlled group (n = 137, SBP/DBP ≥140/90 mmHg).

Results

Older age, decreased history of drinking, a higher proportion of mild-to-moderate hypertension, lower alanine aminotransferase levels, and higher high-density lipoprotein cholesterol levels were observed in the well-controlled group than the poorly controlled group. Higher frequencies of the C allele and AC + CC genotype of AGTR1 A1166C were detected in the well-controlled than the poorly controlled patients (P = 0.005 and P = 0.006). After adjustment for demographic and environmental factors, the CC + AC genotype of AGTR1 A1166C was markedly linked to better hypertension control with valsartan treatment compared to the AA genotype (odds ratio: 2.836, 95% confidence interval: 1.199–6.705, P = 0.018). No significant difference was observed in the allele or genotype distribution of CYP2C9∗3 polymorphism between well-controlled and poorly controlled patients.

Conclusions

The current data suggested that the AGTR1 A1166 C polymorphism may be associated with the antihypertensive effect of valsartan, and carriers with AC and CC genotypes may have a better antihypertensive efficacy response to valsartan treatment.

The association between angiotensin II type 1 receptor A1166C gene polymorphism and the risk of essential hypertension: a meta-analysis

Background

Since first reported having the association with essential hypertension, angiotensin II type 1 receptor (AT1R) A1166C was globally investigated worldwide. However, controversy was found. Furthermore, previous meta-analyses did not adequate to clarify the precise correlation due to some limitations. Therefore, we aimed to perform a meta-analysis concerning the association between AT1R A1166C single-nucleotide polymorphism (SNP) and the risk of essential hypertension with eliminating the limitations of previous studies.

Methods

A meta-analysis was conducted from February to March 2019. Some information related to sample size of hypertension and control groups and genotype frequencies of hypertension and control groups were extracted from each study. Data were analyzed using fixed or random effect model to determine the overall correlation.

Results

A total of 45 papers consisting of 11911 cases and 1340 controls were enrolled for the study. Our overall analysis showed that C allele and AC genotype of AT1R A1166C was associated with 1.18-fold and 1.15-fold respectively increased risk of essential hypertension, while the decreased risk of essential hypertension was observed in A allele and AA genotype. In sub-group analysis, increased risk of essential hypertension was found in C allele, AC genotype, and CC genotype of both Asian population and PCR-RFLP sub-groups, while decreased risk was observed in A allele and AA genotype.

Conclusions

Our meta-analysis reveals that AT1R A1166C remains a valuable SNP having an association with the risk of essential hypertension.

Association of angiotensin ІІ type 1 receptor gene A1166C polymorphism with cancer risk: An updated meta-analysis

Objective:

The association between angiotensin II type 1 receptor (AGTR1) gene A1166C polymorphism and cancer risk has been investigated in many studies. However, the results have been inconclusive. A meta-analysis was performed to obtain a more precise estimation of the relationship.

Methods:

The PubMed and China National Knowledge Infrastructure databases were searched for published literature. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strengths of association.

Results:

Ten studies, including 1553 patients and 1904 controls, were included in the meta-analysis. Overall, there were no significant associations between the AGTR1 gene A1166C polymorphism and cancer risk in the general population (CC vs AA: OR = 1.09, 95% CI = 0.50–2.37; AC vs AA: OR = 1.54, 95% CI = 0.81–2.91; dominant model: OR = 1.46, 95% CI = 0.77–2.79; recessive model: OR = 1.12, 95% CI = 0.84–1.49). In a subgroup analysis by nationality and cancer type, the results also showed no association between this polymorphism and cancer risk.

Conclusions:

This meta-analysis demonstrated that the AGTR1 gene A1166C polymorphism does not appear to be related to the risk of cancer.

Renin-angiotensin system gene polymorphisms and high blood pressure in Lithuanian children and adolescents

Background

Epidemiological studies have demonstrated the influence of environmental factors on HBP in the population of Lithuanian children, although the role of genetic factors in hypertension has not yet been studied. The aim of this study was to assess the distribution of AGTR1, AGT, and ACE genotypes in the Lithuanian child population and to determine whether these genotypes have an impact on HBP in childhood.

Methods

This cross-sectional study enrolled 709 participants aged 12–15 years. The subjects were genotyped for AGT (M235 T, rs699), AGTR1 (A1166C, rs5186), and ACE (rs4340) gene polymorphisms using real-time and conventional polymerase chain reactions. Blood pressure and anthropometric parameters were measured.

Results

The prevalence of HBP was 38.6% and was more frequently detected in boys than in girls (47.9% vs. 29.5%; p < 0.001). No significant differences in the frequencies of the AGT or AGTR1 genotypes or alleles between boys and girls were observed, except for ACE genotypes. The mean SBP value was higher in HBP subjects with ACE ID genotype compared to those with ACE II homozygotes (p = 0.04). No significant differences in BP between different AGT and AGTR1 genotype groups were found. Boys who carried the ACE ID + DD genotypes had higher odds of having HBP than carriers of the ACE II genotype did (controlling for the body mass index (BMI): OR_MH = 1.83; 95% CI, 1.11–3.02, p = 0.024; and controlling for waist circumference (WC): OR_MH = 1.76; 95% CI, 1.07–2.92, p = 0.035). These associations were not significant among girls. The same trend was observed in the multivariate analysis – after adjustment for BMI and WC, only boys with ACE ID genotype and ACE ID + DD genotypes had statistically significantly increased odds of HBP (aOR = 2.05; 95% CI, 1.19–3.53 (p = 0.01) and aOR = 1.82; 95% CI, 1.09–3.04 (p = 0.022), respectively).

Conclusions

The evaluated polymorphisms of the AGT and AGTR1 genes did not contribute to the presence of HBP in the present study and may be seen as predisposing factors, while ACE ID genotypes were associated with significantly increased odds for the development of HBP in the Lithuanian child and adolescent population - especially in boys.

Analysis of Association of Angiotensin II Type 1 Receptor Gene A1166C Gene Polymorphism with Essential Hypertension

The A/C transversion at 1166 of the angiotensin II Type 1 Receptor (AT1R) gene per se does not characterize any functional diversity but has been associated with expression of the AT1R, consequently molecular variants of the gene may modulate the possible risk of essential hypertension. The present study was performed to determine the genotypic frequency of the A1166C polymorphism of the AT1R gene in essential hypertensive patients with the aim to assess the effect of variants of this polymorphism in hypertension. AT1R gene amplification was performed by PCR and A1166C polymorphism was determined by enzyme digestion methodologies in 224 consecutively enrolled essential hypertensive patients and 257 controls. Suitable descriptive statistics was used for different variables. Results revealed that genotype and allele distribution of the A1166C variant differed significantly in hypertensives and normotensives. Allele frequency at the A1166C position was 61%A and 39%C for control and 52%A and 48%C for patients. Observed frequencies were compatible with HWE expected frequencies in cases as well as in controls. rs5186 was found to be associated with hypertension (95% CI 1.1453-2.7932, p: 0.0106). The difference remained statistically significant after the multivariate adjustment (p < 0.05), with C/C variant conferring a risk of 1.74-fold of essential hypertension. This association was confirmed by inter-genotypic variations in the mean systolic and diastolic blood pressure in patients. In conclusion, genetic variation at the AT1R gene influences the risk of hypertension stratification and might serve as a predictive marker for the susceptibility to hypertension among affected families.

Association of angiotensin II type-1 receptor A1166C gene polymorphism with the susceptibility of immunoglobulin A nephropathy

Association of angiotensin II type-1 receptor (AT1R) A1166C gene polymorphism with the susceptibility of immunoglobulin A nephropathy (IgAN) is still controversial. This meta-analysis was conducted to evaluate the association of AT1R A1166C gene polymorphism with IgAN susceptibility. The search was performed in the databases of PubMed, Embase, and Cochrane Library as of 1 May 2014. The eligible investigations were recruited for this meta-analysis. Four literatures on the association between AT1R A1166C gene polymorphism and IgAN susceptibility were identified for this meta-analysis. Interestingly, all the included studies were from Asian population. There was no association between AT1R A1166C gene polymorphism and IgAN susceptibility for overall populations (C allele vs. A allele: OR = 1.04, 95% CI: 0.78-1.39, p = 0.76; CC vs. AC + AA: OR = 1.20, 95% CI: 0.48-2.98, p = 0.70; AA vs. AC + CC: OR = 0.97, 95% CI: 0.70-1.34, p = 0.85), and in Asians. In conclusion, AT1R A1166C gene polymorphism was not associated with IgAN susceptibility in Asian population. However, more case-control association investigations on larger, stratified populations are required in the future.

Association of angiotensin II type 1 receptor (A1166C) gene polymorphism and its increased expression in essential hypertension: a case-control study

OBJECTIVES

Hypertension is one of the major cardiovascular diseases. It affects nearly 1.56 billion people worldwide. The present study is about a particular genetic polymorphism (A1166C), gene expression and protein expression of the angiotensin II type I receptor (AT1R) (SNP ID: rs5186) and its association with essential hypertension in a Northern Indian population.

METHODS

We analyzed the A1166C polymorphism and expression of AT1R gene in 250 patients with essential hypertension and 250 normal healthy controls.

RESULTS

A significant association was found in the AT1R genotypes (AC+CC) with essential hypertension (χ2 = 22.48, p = 0.0001). Individuals with CC genotypes were at 2.4 times higher odds (p = 0.0001) to develop essential hypertension than individuals with AC and AA genotypes. The statistically significant intergenotypic variation in the systolic blood pressure was found higher in the patients with CC (169.4±36.3 mmHg) as compared to that of AA (143.5±28.1 mmHg) and AC (153.9±30.5 mmHg) genotypes (p = 0.0001). We found a significant difference in the average delta-CT value (p = 0.0001) wherein an upregulated gene expression (approximately 16 fold) was observed in case of patients as compared to controls. Furthermore, higher expression of AT1R gene was observed in patients with CC genotype than with AC and AA genotypes. A significant difference (p = 0.0001) in the protein expression of angiotensin II Type 1 receptor was also observed in the plasma of patients (1.49±0.27) as compared to controls (0.80±0.24).

CONCLUSION

Our findings suggest that C allele of A1166C polymorphism in the angiotensin II type 1 receptor gene is associated with essential hypertension and its upregulation could play an important role in essential hypertension.

Expression of angiotensin-converting enzyme gene in whole blood in patients with essential hypertension

OBJECTIVE

The present study aims to investigate the correlation of the angiotensin-converting enzyme (ACE) gene expression and protein expression in patients with essential hypertension in whole blood.

METHODS

ACE gene expression was analyzed by Real Time PCR and western blot in 52 patients with essential hypertension and 42 healthy controls.

RESULTS

We observed a significant increase in Delta threshold cycle (ΔCT) values in the circulating ACE gene and ACE protein expression in patients as compared to controls.

CONCLUSIONS

The up-regulation in relative expression of circulating Angiotensin converting enzyme mRNA and protein in patients with respect to controls might be correlated with high blood pressure in patients with essential hypertension.

Gender specific association of RAS gene polymorphism with essential hypertension: a case-control study

Renin-angiotensin system (RAS) polymorphisms have been studied as candidate risk factors for hypertension with inconsistent results, possibly due to heterogeneity among various genetic and environmental factors. A case-control association study was conducted to investigate a possible involvement of polymorphisms of three RAS genes: AGT M235T (rs699), ACE I/D (rs4340) and G2350A (rs4343), and AGTR1 A1166C (rs5186) in essential hypertensive patients. A total of 211 cases and 211 controls were recruited for this study. Genotyping was performed using PCR-RFLP method. The genotype and allele distribution of the M235T variant differed significantly in hypertensives and normotensives (OR-CI = 2.62 (1.24–5.76), P = 0.006; OR-CI = 0.699 (0.518–0.943), P = 0.018), respectively. When the samples were segregated based on sex, the 235TT genotype and T allele were predominant in the female patients (OR-CI = 5.68 (1.60-25.10), P = 0.002; OR-CI = 0.522 (0.330–0.826), P = 0.005) as compare to the male patients (OR-CI = 1.54 (1.24–5.76), P = 0.34; OR-CI = 0.874 (0.330–0.826), P = 0.506), respectively. For ACE DD variant, we found overrepresentation of “I”-allele (homozygous II and heterozygous ID) in unaffected males which suggest its protective role in studied population (OR-CI = 0.401 (0.224–0.718); P = 0.0009). The M235T variant of the AGT is significantly associated with female hypertensives and ACE DD variant could be a risk allele for essential hypertension in south India.

Angiotensinogen gene polymorphism and ischemic stroke in East Asians: A meta-analysis

Objective:

To investigate the association between angiotensinogen gene M235T polymorphism and ischemic stroke in East Asians.

Data Retrieval:

A computer-based online search was conducted in PubMed, Google scholar, China National Knowledge lnfrastructure database between January 1990 and April 2012 for relevant studies. The key words were angiotensinogen or AGT, polymorphism or genetic and ischemic stroke or cerebral infarction.

Selection Criteria:

Case-controlled studies addressing the correlation between angiotensinogen gene M235T polymorphism and ischemic stroke in East Asians were included. The distribution of genotypes in the included studies was tested for Hardy-Weinberg equilibrium. Quality evaluation of the included studies was conducted by two physicians. Statistical analyses were carried out using Stata 12.0 software for meta-analysis. Heterogeneity tests, sensitivity analysis and publication bias were also conducted.

Main Outcome Measures:

The association between angiotensinogen gene M235T polymorphism and ischemic stroke risk in East Asians was assessed.

Results:

Six relevant studies involving 891 patients with ischemic stroke and 727 controls were included in this meta-analysis. Results showed that there was a significant association between angiotensinogen gene M235T polymorphism and the risk of ischemic stroke in East Asians (T vs. M: odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.10–2.16; TT vs. MM: OR = 2.24, 95%CI = 1.37–3.66; TT vs. MT: OR = 1.76, 95%CI = 1.41–2.20; MM + MT vs. TT: OR = 0.57, 95%CI = 0.46–0.70). Sensitivity analysis confirmed that the study results were stable and reliable, with no publication bias.

Conclusion:

The angiotensinogen gene M235T polymorphism is associated with ischemic stroke in East Asians, and the TT genotype and T allele are risk factors for ischemic stroke.

A systematic review and meta-analysis of the association between angiotensin II type 1 receptor A1166C gene polymorphism and myocardial infarction susceptibility

BACKGROUND AND AIM

Many reported studies have been conducted to investigate the association of angiotensin II type 1 receptor (AT1R) A1166C gene polymorphism with myocardial infarction (MI) susceptibility. However, the results from those reports are still conflicting. This meta-analysis was performed to study the relationship between AT1R A1166C gene polymorphism and MI risk.

METHOD

The databases of PubMed, Embase, and Cochrane Library were searched as of 1 March 2012, and eligible investigations were recruited into this meta-analysis.

RESULTS

Eighteen investigations were identified for the analysis of association between AT1R A1166C gene polymorphism and MI risk, 11 in Caucasians, three in Asians, two in Africans, one in the population of Brazil and one in the population of Durban, South Africa . There was a marked association between AT1R C allele and MI susceptibility for overall populations (odds ratio (OR)=1.12, 95% confidence interval (CI): 1.01-1.25, p=0.03), and AT1R AA genotype was associated with a lower risk of MI in overall populations (OR=0.87, 95% CI: 0.78-0.98, p=0.02). However, AT1R A1166C gene polymorphism was not associated with MI risk in the sub-groups of Caucasians, Asians, Africans, Brazil and Durban populations.

CONCLUSIONS

C allele is a risk factor for the MI susceptibility in overall populations, and AA genotype might be a protective factor against the MI risk in overall populations. However, more case-control association investigations on larger, stratified populations are required in the future.

Effect of angiotensin II type I receptor A1166C polymorphism on benazepril action in hypertensive patients: a family-based association test study

BACKGROUND

Few studies have examined the effect of the angiotensin II type I receptor (AT1R) A1166C polymorphism on the antihypertensive effect of the angiotensin-converting-enzyme inhibitor benazepril in patients with hypertension, and no such studies have performed analysis using the Family-Based Association Test (FBAT), The aim of our study was to examine the association between AT1R A1166C gene polymorphism and the antihypertensive effect of benazepril using the FBAT.

METHODS AND RESULTS

A total of 864 patients (aged, 26-62 years) with essential hypertension were identified in an epidemiological survey and enrolled in this study. Blood pressure (BP) was measured before and after 16 days of treatment with benazepril (10 mg/day). The association between the A1166C gene polymorphism and the antihypertensive effect of benazepril was assessed by FBAT. The frequencies of alleles A and C were 95.1% and 4.9%, respectively. FBAT analysis revealed that the C allele was significantly associated with high baseline diastolic BP (Z = 2.041, p = 0.041), decreased systolic BP after treatment (Z = 2.549, p = 0.011), and decreased diastolic BP after treatment (Z = 2.320, p = 0.020).

CONCLUSION

Our results, determined using the FBAT, are the first evidence that the AT1R A1166C polymorphism may increase the antihypertensive effect of benazepril in patients with hypertension.

Pharmacogenetics and rational drug use around the world

The WHO embraces evidence-based medicine to formulate an essential medicines list (EML) considering disease prevalence, drug efficacy, drug safety and cost-effectiveness. The EML is used by developing countries to build a national formulary. As pharmacogenetics in developed countries evolves, the Pharmacogenetics for Every Nation Initiative (PGENI) convened with representatives from China, Mexico, Ghana and South Africa in August 2009 to evaluate the use of human pharmacogenetics to enhance global drug use policy. The diseases causing mortality, the lack of integration of pharmacovigilance at the national formulary level, the pharmacogenetics research agenda and pharmacogenetics clinician education did not differ greatly among the countries. While there are many unanswered questions, systematically incorporating pharmacogenetics at the national formulary level promises to improve global drug use.

Association between the angiotensinogen gene T174M polymorphism and hypertension risk in the Chinese population: a meta-analysis

No consensus has been reached on the association between the angiotensinogen gene polymorphism T174M and hypertension risk in the Chinese population. We conducted a meta-analysis to systematically pursue their possible association. Case-control studies in the Chinese and English publications were identified by searching the MEDLINE, EMBASE, CBM, CNKI, Wanfang and VIP databases. The fixed-effects model and the random-effects model were applied for dichotomous outcomes to combine the results of the individual studies. After this, we selected 16 studies that met the inclusion criteria. In total, the selected studies contributed a study population containing 3828 hypertensive patients and 3251 normotensive controls. We found no statistical association between the T174M polymorphism and hypertension risk in all subjects, in a Han Chinese subgroup or in non-Han Chinese minorities. However, a statistically significant association was observed between the T174M polymorphism and a hypertensive group (systolic blood pressure ≥160 mm Hg and/or diastolic blood pressure ≥95 mm Hg) in the dominant genetic model (MM+MT vs. TT: P=0.03, odds ratio=1.71, 95% confidence interval 1.07-2.74, P(heterogeneity)=0.27, I(2)=24%, fixed-effects model). No evidence of publication bias was observed. More studies, especially studies stratified for different stages of hypertension, should be performed in the future to fully examine this question. Studies investigating gene-gene interactions, gene-environment interactions, as well as their mutual interactions will also be important.

Angiotensin II type 1 receptor gene polymorphism and telomere shortening in essential hypertension

Several genetic studies were carried out among hypertensive patients to assess allelic association at the 1166 position of the 3' untranslated region of angiotensin II type 1 receptor gene. In addition, attempts have also been made to find out whether telomere length attrition is associated with hypertension. The main aim of this study was to examine the association of A1166C polymorphism of angiotensin II type 1 receptor and telomere length with essential hypertension in Egyptian people. Angiotensin II type 1 genotyping and relative telomere length were investigated by PCR in 40 patients of essential hypertension and 15 healthy controls. The homozygous AA1166 allele frequency was 92.8% among the studied subjects. There was no intergroup variation in A allele frequency in normotensive group. The frequency of homozygous A allele was significantly higher in hypertensive than normotensive subjects (97.5 and 80%, respectively) with higher frequencies in male patients. The average telomere length ratio was significantly shorter in hypertensive than in normal subjects (1.08 ± 0.3 and 1.54 ± 0.18, respectively). No correlation was observed between telomere length ratio and body mass index. This study suggests that the homozygous A1166 allele of angiotensin II type 1 and short telomeres may be predisposing factors for essential hypertension in Egyptians and may be involved in the pathogenesis of the disease. Further strategies for treating high-risk patients could result in prevention or delay of end organ damage.

Association of the angiotensin II type I receptor gene +1166 A>C polymorphism with hypertension risk: evidence from a meta-analysis of 16474 subjects

Mounting evidence suggests the potential susceptibility of individuals with a mutation in the angiotensin II type I receptor (AT1R) gene to hypertension. One polymorphism, +1166 A>C, has been extensively studied, but the results have often been irreproducible. We therefore aimed to meta-analyze all available case-control studies from the English language literature to explore the association of this polymorphism with hypertension. A total of 22 studies with 24 populations involving 8249 patients and 8225 controls were identified as of 25 February 2010. A random-effects model was performed regardless of the between-study heterogeneity. The study quality was assessed in duplicate. The data were analyzed using RevMan software (version 5.0.23). Overall, the presence of the +1166 C allele significantly conferred an increased risk of hypertension (odds ratio (OR)=1.14; 95% confidence interval, 1.00-1.30; P=0.05). Under the assumption of three genetic modes of inheritance, an elevated hypertension risk was observed for each comparison (codominant: AC vs. AA, OR=1.10 (P=0.20) and CC vs. AA, OR=1.21 (P=0.36); dominant: OR=1.13 (P=0.09); recessive: OR=1.21 (P=0.36)). Upon stratification by study design, more obvious associations were observed for the population-based design, whereas there were no changes in direction and only slight changes in magnitude upon stratification by sample size and geographical area. No publication biases were indicated by the fail-safe number. Our study pooled previous findings and showed that the AT1R +1166 C allele conferred an increased risk of hypertension. We suggest that confirmation in a large, well-designed study or from functional aspects of this polymorphism is critical.