A1166C polymorphism of the angiotensin II type 1 receptor gene and essential hypertension in Han, Tibetan and Yi populations

Distributive characteristics of the CYP2C9 and AGTR1 genetic polymorphisms in Han Chinese hypertensive patients: a retrospective study

Background

There is an individual variation in response to antihypertensive effect of the angiotensin II receptor antagonist. This study aimed to determine the allele and genotype frequencies of CYP2C9 and AGTR1 genetic polymorphisms and explore the potential role of these polymorphisms in guiding the selection of angiotensinIIreceptor antagonist in Han Chinese hypertensive patients.

Methods

Totally 2419 Han Chinese hypertensive patients and 126 normotensive controls were recruited in this study. Venous blood samples were collected from each patient, and the genetic polymorphisms of CYP2C9 and AGTR1 were assessed using a gene chip platform. The allele and genotype frequency of each gene and the combined genotypes in this study were analyzed respectively.

Results

The gene chip analysis identified an allelic frequency of 96.51% for CYP2C9*1 and 3.49% for CYP2C9*3 in the cohort of Han Chinese hypertensive patients. Statistical analysis showed that the frequency of wild-type homozygous for CYP2C9*1/*1 was 93.30%, while the frequency of heterozygous for *1/*3 or mutant homozygous for *3/*3 was 6.41% or 0.29%. Meanwhile, we detected allelic frequencies of 95.06% and 4.94% for the A and C allele of AGTR1, respectively. While the genotype frequency of wild-type homozygous for AA was 90.41%, the frequency of heterozygous for AC or mutant homozygous for CC was 9.30% or 0.29%. Notably, we observed that 84.66% (2048/2419) of the subjects exhibited a combined genotype of CYP2C9 and AGTR1 as *1/*1 + AA, while the combined genotypes *3/*3 + AC or *3/*3 + CC were not detected in hypertension patients. Besides, no significant association was found between normotensive controls and hypertensive patients, or among the three grades of hypertensive patients.

Conclusions

These data revealed the polymorphisms characteristics of CYP2C9 and AGTR1 in Han Chinese hypertensive patients, providing valuable information for genotype-based antihypertension therapy in prospective clinical studies in the future.

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.

Contribution of Four Polymorphisms in Renin-Angiotensin-Aldosterone-Related Genes to Hypertension in a Thai Population

Introduction

The roles of genes in the renin-angiotensin-aldosterone system (RAAS) in hypertension, including angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II receptor type 1 (AGTR1), and aldosterone synthase (CYP11B2), have been widely studied across different ethnicities, but there has been no such investigation in Thai population.

Materials and Methods

Using 4,150 Thais recorded in the Electricity Generating Authority of Thailand (EGAT) study, we examined the association of rs1799752, rs699, rs5186, and rs1799998 located in or near ACE, AGT, AGTR1, and CYP11B2 genes in hypertension. We investigated their roles in hypertension using multivariate logistic regression and further examined their roles in blood pressure (BP) using quantile regression. Sex, age, and BMI were adjusted as potential confounders.

Results

We did not observe associations between hypertension and rs1799752 (P=0.422), rs699 (P=0.36), rs5186 (P=0.49), and rs1799998 (P=0.71). No evidence of association between these SNPs and BP was found across an entire distribution. A nonlinear relationship between age and BP was observed.

Conclusion

In Thai population, our study showed no evidence of association between RAAS-related genes and hypertension. While our study is the first and largest study to investigate the role of RAAS-related genes in hypertension in Thai population, restricted statistical power due to limited sample size is a limitation.

Association of with-no-lysine kinase 1 and Serine/Threonine kinase 39 gene polymorphisms and haplotypes with essential hypertension in Tibetans

Tibetans have a higher essential hypertension prevalence compared with other ethnics in China. The reason might be due to their unique environmental influence, as well as genetic factor. However, limited studies focus on Tibetan genetics and its association with hypertension. The aim of this study was to investigate the association between With-No-Lysine (K) Kinase 1 (WNK1), Serine/Threonine kinase 39(STK39) genes variants and hypertension in the Tibetan population. 204 Tibetan hypertensive patients and 305 normotensive controls were recruited in an epidemiological survey conducted at 2 sites in the Ganzi Tibetan autonomous region. Patients were genotyped for nineteen WNK1 candidate tag single nucleotide polymorphisms (SNPs) and three STK39 SNPs, and haplotype analysis was performed. Results showed that the allele A in rs1468326 was overrepresented in hypertensive patients versus control (53.4% vs 42.9%, P < 0.05). The multivariable-adjusted odds ratio (OR) for hypertension among CA + AA genotypes carriers was 1.60 (95% CI: 1.02-2.62, P < 0.05), and they also had a higher systolic blood pressure (136.5 ± 28.6 vs 131.7 ± 24.8 mmHg, P < 0.05). However, the TT genotype ratio in rs6749447 was lower in hypertensives (5.4% vs 10.8%, P < 0.05), and the hypertension risk for the TT genotype carriers in rs6749447 decreased after adjustment (OR 0.49, 95% CI 0.19-0.95, P < 0.05). Subjects with haplotype AGACAGGAATCGT showed 1.57 times higher risk of hypertension (95% CI 1.02-2.41, P < 0.05). In conclusion, SNP rs1468326 of WNK1, rs6749447 of STK39, and WNK1 haplotype AGACAGGAATCGT were associated with hypertension in Tibetan individuals. Environ. Mol. Mutagen. 59:151-160, 2018. © 2017 Wiley Periodicals, Inc.

SNPs, linkage disequilibrium, and chronic mountain sickness in Tibetan Chinese

Chronic mountain sickness (CMS) is estimated at 1.2% in Tibetans living at the Qinghai-Tibetan Plateau. Eighteen single-nucleotide polymorphisms (SNPs) from nine nuclear genes that have an association with CMS in Tibetans have been analyzed by using pairwise linkage disequilibrium (LD). The SNPs included are the angiotensin-converting enzyme (rs4340), the angiotensinogen (rs699), and the angiotensin II type 1 receptor (AGTR1) (rs5186) from the renin-angiotensin system. A low-density lipoprotein apolipoprotein B (rs693) SNP was also included. From the hypoxia-inducible factor oxygen signaling pathway, the endothetal Per-Arnt-Sim domain protein 1 (EPAS1) and the egl nine homolog 1 (ENGL1) (rs480902) SNPs were included in the study. SNPs from the vascular endothelial growth factor (VEGF) signaling pathway included are the v-akt murine thymoma viral oncogene homolog 3 (rs4590656 and rs2291409), the endothelial cell nitric oxide synthase 3 (rs1007311 and rs1799983), and the (VEGFA) (rs699947, rs34357231, rs79469752, rs13207351, rs28357093, rs1570360, rs2010963, and rs3025039). An increase in LD occurred in 40 pairwise comparisons, whereas a decrease in LD was found in 55 pairwise comparisons between the controls and CMS patients. These changes were found to occur within and between signaling pathways, which suggests that there is an interaction between SNP alleles from different areas of the genome that affect CMS.

A1166C polymorphism of the angiotensin II type 1 receptor gene contributes to hypertension susceptibility: evidence from a meta-analysis

Background The angiotensin II type 1 receptor (AT1R) gene is a prime candidate for polymorphisms that could contribute to hypertension. A polymorphism in the 3' untranslated region, leading to the transversion of adenine to cytosine at position 1166, has been the most-studied variant. However, the results have been inconsistent, and we therefore performed a meta-analysis to evaluate the association of this polymorphism with hypertension. Methods We conducted an extended a computer-based literature search of PubMed and Web of Knowledge up to November 30, 2015. The extracted data were analysed statistically, and pooled odds ratios with 95% confidence intervals were calculated to assess the strengths of associations using Review Manager software (version 5.2). Results After removing 5 studies that were not consistent with the Hardy-Weinberg equilibrium, we finally collected 41 case-control studies involving 11,837 cases and 11,020 controls to evaluate the association between AT1R polymorphisms and hypertension. We found that the risk of hypertension was higher for allele C than for allele A under the codominant model, significantly higher for genotype CC + AC than for genotype AA under the dominant model, and significantly higher for genotype CC + AC in Caucasians. Conclusion This meta-analysis suggests that the AT1R 1166 CC + AC genotype consistently confers susceptibility to hypertension and that early preventive measures should be applied in clinical settings according to patient genotypes.

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.

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.

The A(1166)C polymorphism of the AT1R gene is associated with an early onset of hypertension and high waist circumference in Jordanian males attending the Jordan University Hospital

There is no agreement on the involvement of angiotensin II type 1 receptor (AT1R) gene A(1166)C variant and essential hypertension. The purpose of this study was to investigate the association between angiotensin II type 1 receptor (AT1R) gene A(1166)C variants with essential hypertension and some related parameters in a sample of Jordanian hypertensive patients. DNA samples from 108 hypertensive individuals and 102 age- and gender-matched non-hypertensive controls of the Jordanian population were analyzed by polymerase chain reaction followed by restriction fragment length polymorphism assay (PCR-RFLP) methods to determine the frequency of A(1166)C variants alleles. No statistically significant differences were found in the distribution of alleles and genotypes between hypertensive and non-hypertensive individuals, not even after gender segregation. The frequency of the variant allele (C(1166)) was significantly higher in the early-onset compared to the late-onset group of hypertensive males, in subjects with positive family history of hypertension, and in subjects with high waist circumference. In conclusion, the A(1166)C polymorphism is not associated with essential hypertension in Jordanian hypertensive individuals. However, it was associated with an early onset of hypertension in males, with positive family history of hypertension, and with high waist circumference irrespective of blood pressure status.

Genetic variants in the renin-angiotensin-aldosterone system and blood pressure responses to potassium intake

OBJECTIVE

Observational epidemiologic studies and clinical trials have documented that dietary potassium intake lowers blood pressure (BP). We examined the association between genetic variants in the renin-angiotensin-aldosterone system and BP responses to potassium intervention.

METHODS

A 7-day high-sodium followed by a 7-day high-sodium plus 60 mmol/day potassium-supplementation feeding study was conducted among 1906 participants from rural northern China. Nine BP measurements were obtained at each intervention phase using a random-zero sphygmomanometer and 181 single-nucleotide polymorphisms (SNPs) in 11 candidate genes of the renin-angiotensin-aldosterone system were used for analyses.

RESULTS

Several SNPs in nuclear receptor subfamily 3, group C, member 2 (NR3C2), angiotensin II type 1 receptor (AGTR1), hydroxysteroid (11-beta) dehydrogenase 1 (HSD11B1), and hydroxysteroid (11-beta) dehydrogenase 2 (HSD11B2) genes were significantly associated with BP responses to potassium intervention. For example, the number of G alleles of the N554S missense mutation (rs5527) of NR3C2 was significantly associated with greater SBP responses to potassium intervention; mean [95% confidence interval (CI)] responses (mmHg) were -3.33 (-3.65 to -3.02) for genotype A/A and -5.47 (-6.64 to -4.29) for A/G, respectively (P value = 0.0004). In addition, the number of C alleles of the A1166C variant (rs5186) in AGTR1 was significantly and inversely associated with SBP responses to potassium intervention; mean (95% CI) responses were -3.55 (-3.87 to -3.24) for genotype A/A, -2.45 (-3.27 to -1.62) for A/C, and 3.25 (-5.73 to 12.23) for CC (P value = 0.003).

CONCLUSION

These novel findings indicated that genetic variants in the renin-angiotensin-aldosterone system may play an important role in determining an individual's BP responses to dietary potassium intake.

Association of angiotensin II type 1 receptor gene A1166C polymorphism with the presence of diabetes mellitus and metabolic syndrome in patients with documented coronary artery disease

BACKGROUND

There are relatively limited data available on the genetic susceptibility to diabetes mellitus and metabolic syndrome in the Iranian population. We have therefore investigated the association between the angiotensin II type I receptor gene polymorphism (AT(1)R/A1166C) and the presence of diabetes mellitus and metabolic syndrome in a well defined group of patients.

METHODS

Patients with angiographically defined coronary artery disease (CAD) (n=309) were evaluated for the presence of AT(1)R/A1166C polymorphism. These patients were classified into subgroups with (n=164, M/F: 109/55) and without (n=145, M/F: 84/61) diabetes mellitus. The AT(1)R polymorphism was assessed using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based method.

RESULTS

There was a higher frequency of polymorphic genotypes (AC+CC) in the diabetic compared with the non-diabetic group (p=0.01). When determined for each gender separately, this difference remained significant in the males (p=0.04) but not in females (p=0.09). With regard to the allele frequencies, the C allele was significantly higher and the A allele frequency was lower in the diabetic group (p=0.01). This remained significant after gender segregation for males (p=0.01) but not females. In the binary logistic regression analysis, only serum fasting glucose was found as the independent predictor for the presence of diabetes in the CAD patients (β=1.16, p<0.001 for total population and β=1.29, p<0.001 for male subjects). There was no significant difference in genotype or allele frequencies between subgroups with and without metabolic syndrome, this being unaffected by gender or the definition of metabolic syndrome used apart from a significantly lower frequency of C allele in male subjects with metabolic syndrome defined by the NCEP ATP III criteria (p=0.04).

CONCLUSION

The AT(1)R/A1166C polymorphism may be associated with the presence of diabetes mellitus in male subjects with documented CAD.

Interactions of renin–angiotensin system gene polymorphisms and antihypertensive effect of benazepril in Chinese population

Aim: Angiotensin-converting enzyme inhibitors are widely used antihypertensive drugs with individual response variation. We studied whether interactions of AGT, AGTR1 and ACE2 gene polymorphisms affect this response. Materials & methods: Our study is based on a 3-year field trial with 1831 hypertensive patients prescribed benazepril. Generalized multifactor dimensionality reduction was used to explore interaction models and logistic regressions were used to confirm them. Results: A two-locus model involving the AGT and ACE2 genes was found in males, the sensitive genotypes showed an odds ratio (OR) of 1.9 (95% CI: 1.3–2.8) when compared with nonsensitive genotypes. Two AGT–AGTR1 models were found in females, with an OR of 3.5 (95% CI: 2.0–5.9) and 3.1 (95% CI: 1.8–5.3). Conclusion: Gender-specific gene–gene interactions of the AGT, AGTR1 and ACE2 genes were associated with individual variation of response to benazepril. Further studies are needed to confirm this finding.

Original submitted 1 November 2010; Revision submitted 10 January 2011

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.

Prevalence and risk factors of chronic kidney disease: a population study in the Tibetan population

BACKGROUND

The prevalence of chronic kidney disease (CKD) at high altitude is not known. We conducted a population-based survey in Tibet to identify the prevalence and associated risk factors of CKD in subjects living at altitudes of > 3500 m.

METHODS

One thousand two hundred and eighty-nine Tibetans (≥ 18 years) from four districts of Lhasa city (altitude 3658 m) and eight villages of Dangxiong County (altitude 4200 m) were interviewed and tested for haematuria, albuminuria and estimated glomerular filtration rate (eGFR).

RESULTS

The adjusted prevalence of hypertension, albuminuria, haematuria and reduced eGFR were 38.8% (95% CI: 36.2-41.5%), 16.2% (95% CI: 14.1-18.2%), 3.9% (95% CI: 2.8-4.9%) and 2.1% (95% CI: 1.3-2.9%), respectively. Both the presence of hypertension and the presence of albuminuria were strongly and independently associated with hyperuricaemia and elevated haematocrit.

CONCLUSIONS

This is the first population-based epidemiological study of CKD in the Tibetan population. We found a higher prevalence of CKD and associated high prevalence of albuminuria, hypertension, hyperuricaemia and high haematocrit in the Tibetan population. The present study indicates the urgent need to develop comprehensive strategies targeted at reducing the CKD burden in this area and may lead to a better understanding of CKD in high-altitude populations.

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.

Genetic associations with mountain sickness in Han and Tibetan residents at the Qinghai-Tibetan Plateau

BACKGROUND

Acute (AMS) and chronic (CMS) mountain sicknesses are illnesses that occur among humans visiting or inhabiting high-altitude environments, respectively. Some individuals are genetically less fit than others when stressed by an extreme high-altitude environment. Seven blood physiological parameters and five genetic polymorphisms were studied in Han patients with AMS and Tibetan patients with CMS.

METHODS

We compared 98 AMS patients with 60 Han controls as well as 50 CMS patients with 36 Tibetan controls. The genetic loci studied are ACE I/D (rs4340), AGT M235T (rs699), AGTR1 A1166C (rs5186), GNB3 A(-350)G (rs2071057) and APOB A/G (rs693).

RESULTS

All physiological parameters (RBC, HCT, Hb, SaO(2), HR, and BPs/d) studied significantly changed in the CMS patients while SaO(2) and HR changed in the AMS Han patients compared to their controls. The ACE D and AGT 235M alleles were found to be significantly associated with AMS and CMS, respectively, while a significantly high incidence of the G-protein (GNB3) (-350)A allele was found in the AMS patients. ACE (I/D) was significantly associated with HR in CMS patients while the AGT M235T was significantly associated with SaO(2) and BPs/d in AMS patients. APOB A/G was significantly associated with BPs/d in AMS and HR in CMS patients.

CONCLUSION

AMS and CMS share very similar genetic results for the ACE I/D and AGT M235T polymorphisms indicating that these mutations have an effect on both illnesses.

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

Introduction. We performed a meta-analysis with the aim of assessing the association of the angiotensin II type 1 (AT1) receptor gene A1166C polymorphism with essential hypertension in Chinese case-control studies. Methods. Studies were searched from the Chinese Biomedicine Database, the China National Knowledge Infrastructure platform, Pubmed and Medline, using the search terms ‘hypertension’, ‘angiotensin II type 1 receptor’, ‘AT1R’, ‘polymorphism’, ‘China’ and ‘Chinese’, without limiting to any specific language. The strength of the association between the A1166C polymorphism and hypertension was evaluated by the odds ratio (OR) with the corresponding 95% confidence interval (CI). The analyses were performed with Cochrane RevMan software version 4.2.

Results. Overall, the variant genotype AC/CC was associated with a statistically increased essential hypertension risk with the pooled OR 1.48 (95% CI: 1.20—1.83). In the subgroup analyses, the association was also significant among studies using Northern populations, Southern populations, Han Chinese and hospital-based controls. The age did not influence the relationship between the AT 1 receptor A1166C polymorphism and hypertension in the subgroup analyses.

Conclusions. The present meta-analysis suggests that the AT1 receptor 1166 AC/CC genotype is associated with susceptibility to hypertension in the Chinese population.

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.

Association between angiotensinogen, angiotensin II receptor genes, and blood pressure response to an angiotensin-converting enzyme inhibitor

BACKGROUND

To identify the genetic contribution to the variation in blood pressure (BP) response to angiotensin-converting enzyme inhibitors (ACEIs), single-nucleotide polymorphisms (SNPs) in the angiotensinogen (AGT), angiotensin receptor 1 (AGTR1), and angiotensin receptor 2 (AGTR2) genes were evaluated for their association with BP response to ACEI in Chinese patients with hypertension in a 2-stage design.

METHODS AND RESULTS

We selected 1447 hypertensive patients from a 3-year benazepril postmarket surveillance trial and genotyped them for 14 SNPs in the AGT, AGTR1, and AGTR2 genes. The AGT rs7079 (C/T) SNP (3'-untranslated region) was significantly associated with the response of diastolic BP to benazepril (diastolic BP response: -7.4 mm Hg for subjects with the CC genotype, -8.9 mm Hg for CA, and -10.1 mm Hg for AA; P=0.001). Although there was no association of individual SNPs in the AGTR1 gene, there was a graded response between common haplotypes and systolic BP reduction in the order of haplotype 2 (H2)/lack of haplotype 3 (non-H3) (-13.6 mm Hg) > non-H2/non-H3 (-10.9 mm Hg) > H3/non-H2 (-6.6 mm Hg) (P=0.004). The total variations in response to ACEI therapy that were explained by the AGT SNP and AGTR1 haplotype groups were 13% for systolic and 9% to 9.6% for diastolic BP, respectively.

CONCLUSIONS

AGT SNP rs7079 and AGTR1 haplotypes were associated with BP reduction in response to ACEI therapy in hypertensive Chinese patients. This will be useful in future studies, providing genetic markers to predict the hypertensive response to ACEI therapy.

Association of the C-344T polymorphism of CYP11B2 gene with essential hypertension in Hani and Yi minorities of China

BACKGROUND

Aldosterone synthase (CYP11B2) is a key enzyme in the biosynthesis of aldosterone. Recently, a C-344T polymorphism in the promoter region of the CYP11B2 gene has been reported to be in association with high blood pressure. We investigated the association between this polymorphism and essential hypertension in Hani (n=305 individuals) and Yi (n=233 individuals) minorities of China.

METHODS

CYP11B2 genotyping with polymerase chain reaction-restriction fragment length polymorphism was performed in 267 normotensive subjects and 271 essential hypertensive subjects. At the same time, the T(-344)C polymorphism detection in 33 subjects was also performed by sequencing.

RESULT

The frequency of CYP11B2 C-344T genotype in normotensive controls and essential hypertensive cohort in Hani population were TT: 0.729 vs. 0.610; CT + CC: 0.271 vs. 0.390, respectively. The frequency of CYP11B2 C-344T genotype in normotensive controls and essential hypertensive cohort in Yi population were TT: 0.612 vs. 0.475; CT + CC: 0.388 vs. 0.525, respectively. The frequency of CC + CT genotype in the essential hypertensive group was significantly higher than that in the normotensive controls in both Hani and Yi populations (P<0.05).

CONCLUSION

The -344C allele of the CYP11B2 may play a role in genetic predisposition to developing essential hypertension in Hani and Yi minorities of China.

T102C genetic polymorphism of the 5-HT2A receptor in Chinese hypertensive patients and healthy controls

1. The 5-HT(2A) receptor belongs to the G-protein superfamily. It plays an important role in vascular regulation. 2. Previous reports in the UK have indicated that there is an association of the T102C genetic polymorphism of the 5-HT(2A) receptor with hypertension, but no studies have been made on the T102C genetic polymorphism in Chinese hypertensive patients. In the present study, we investigated the T102C genetic polymorphism of 5-HT(2A) receptors in Chinese hypertensive patients to determine whether there is an association of this polymorphism with hypertension in Chinese. 3. The present study was conducted on 198 hypertensive patients and 164 healthy controls. Polymerase chain reaction-restriction fragment length polymorphism was used to identify the T102C genetic polymorphism of the 5-HT(2A) receptor. 4. In the present study, the C allele frequency of the 5-HT(2A) receptor genetic polymorphism was 0.343 in hypertensive patients, which was not significantly different to that in healthy controls (0.393; chi(2) = 1.922; P = 0.166; odds ratio = 0.807, 95% confidence interval 0.596-1.093). In addition, no gender differences were observed. 5. In conclusion, to our knowledge, this is the first report on the T102C genetic polymorphism of the 5-HT(2A) receptor in Chinese hypertensive patients. We find that no correlation exists between the T102C genetic polymorphism and hypertension, which affords useful information on the pathogenesis of hypertension in the Chinese population.

Association between angiotensin II type 1 receptor gene polymorphism and essential hypertension: the Ohasama Study

Gene targeting approaches have suggested that the angiotensin II type 1 receptor (AT1R) is involved in blood pressure (BP) regulation and modulation of the effect of angiotensin II. The A1166C polymorphism of the AT1 receptor gene (AT1R/A1166C) is associated with hypertension in Caucasians, but not in Japanese. The goal of this study, the Ohasama Study, was to examine the association between AT1R/A1166C and hypertension, especially home BP, in the Japanese general population. The Ohasama Study was a cohort study based on Japanese rural residents of Ohasama Town in the northern part of Japan. Subjects who gave informed consent to the study protocol and genetic analysis were recruited. Home BP was measured twice in the morning within 1 h of waking up and in the evening just before going to bed. The TaqMan polimerase chain reaction (PCR) method clearly determined AT1R/A1166C genotypes (n =1,207). The genotype distribution of AT1R/A1166C was as follows: AA 84%; AC 15%; CC 1%. There was almost no difference in baseline characteristics among the AT1R genotypes (AA, AC, CC). In the subjects not receiving antihypertensive medication (n =817), both casual BP and home BP were not different among the AT1R genotypes after adjusting for confounding factors (age, sex, body mass index, current smoking habit and current alcohol consumption). The frequency of hypertension showed no difference among AT1R genotypes after adjusting for confounding factors, though the AC and CC genotypes were more frequent in hypertensives than in normotensives. Our data suggested that the AT1R/A1166C polymorphism is not a major genetic predisposing factor for hypertension in Japanese.

Genetics of human hypertension

Hypertension is a complex genetic disorder caused by interplay between several "risk" genes and environmental factors (genetic heritability approximately 30%). Most genetic studies of hypertension use a candidate gene approach and two conclusions have been made: there is no association or linkage with the genes studied, or the hypertension phenotype is heterogeneous and subgroups with hypertension related to certain polymorphisms cannot be identified because of background noise. Studies using intermediate phenotypes suggest the latter is most likely. Another problem is the reliability of gene structure assessment: usually only one or two gene polymorphisms are assessed. The use of intermediate phenotypes and dense mapping of candidate genes would provide a better approach for identifying genotype-phenotype correlations, which might enable the use of genotypes to identify more-specific therapeutic and preventative measures for hypertensives.

A/C1166 gene polymorphism of the angiotensin II type 1 receptor (AT1) and ambulatory blood pressure: the Ohasama Study

We previously investigated the relation between hypertension and each of three major genetic polymorphisms in the renin-angiotensin (AGT)-aldosterone system (R-A-A), AGT M235T, angiotensin convert enzyme (ACE) I/D, and CYP11B2 -344C/T, by means of ambulatory blood pressure (ABP) monitoring in a general Japanese population (the Ohasama Study). A/C1166 gene polymorphism in the 3' untranslated region of the angiotensin II type 1 receptor (AT1) gene is the final remaining major target in R-A-A to be examined in the Ohasama Study population. In the present study, the AT1 A/C1166 polymorphism was genotyped by the TaqMan polymerase chain reaction (PCR) method or restriction fragment length polymorphism (RFLP) in 802 Japanese subjects aged 40 and over, who were previously genotyped for the AGT M235T, ACE D/I, CYP11B2 -344C/T polymorphisms. The AA genotype, AC genotype, and CC genotype were present in 678 (84.5%), 121 (15.1%), and 3 (0.4%) of subjects, respectively. Since the frequency of the C allele was quite low (0.079), the genotypes were classified according to the presence or absence of the C allele. Although daytime blood pressure (BP) was higher in subjects with the C allele, the difference was not statistically significant after adjusting for age, gender, body mass index, and smoking status. No significant difference was noted in the prevalence of cardiovascular diseases or nocturnal BP decline between the two groups. These results indicated that AT1 A/C1166 polymorphism was not associated with any clinical parameters associated with hypertension or atherosclerosis in the Japanese population.