Association between angiotensin II type 1 receptor gene polymorphisms and ischemic stroke: a meta-analysis

Genetic Variants Associated with High Susceptibility of Premature Ischemic Stroke

Background

Several polymorphisms had been associated with an increased risk of ischemic stroke, but results are inconclusive. The aim of this study was to examine the association between AGTR1 A1166C and TSP-1 N700S polymorphisms and ischemic stroke in a young Mexican population.

Methods

In a case-control study, 250 patients ≤ 45 years of age with ischemic stroke and 250 controls matched by age and gender were included. The polymorphisms were determined in all participants by polymerase chain reaction.

Results

There were statistical differences in genotype distribution (p = 0.01) and allele frequency (p = 0.001) of AGTR1 A1166C polymorphism. In contrast, there was a similar genotype distribution (p = 0.96) and allele frequency (p = 0.76) of the TSP1 N700S genetic variant between groups. Hypertension (p = 0.03), smoking (p = 0.02), and family history of atherothrombotic disease (p = 0.04) were associated with stroke, but not diabetes (p = 0.30) and dyslipidemia (p = 0.08).

Conclusions

This is the first study in Mexican population to explore several genetic variants in young patients with ischemic stroke. Our results suggest that polymorphisms in the renin-angiotensin-aldosterone system could contribute to premature hypertension, endothelial dysfunction, atherothrombosis, vasoconstriction, smooth muscle cell migration, and proliferation. In contrast, polymorphisms in the coagulation factors are not associated with ischemic stroke. Environmental factors such as diabetes and dyslipidemia could be less important in the pathogenesis of ischemic stroke at a young age. We suggest that those polymorphisms should be determined in individuals with a family history of thrombosis to avoid the stroke development. Therefore, genotype-environmental combination could determine several possible phenotypes at different moments in life.

Association of miR-155 and Angiotensin Receptor Type 1 Polymorphisms with the Risk of Ischemic Stroke in a Chinese Population

There is increasing evidence suggesting that dysregulation of miR-155 and its target angiotensin receptor type 1 (AT1R) are linked to the incidence of ischemic stroke (IS), but the underlying mechanisms remain to be clarified. In this study, we therefore sought to investigate how miR-155 and AT1R polymorphisms affect IS risk. We included 579 IS patients and 509 age-matched controls in the present analysis, genotyping individuals for the rs767649 polymorphism in miR-155, as well as for the rs1492099 and rs275653 polymorphisms in AT1R via iMLDR-TM genotyping technology. The allele and genotype frequencies for the assessed polymorphisms were comparable in IS patients and controls, without any detectable association between AT1R haplotype and IS risk. We conducted additional trial of ORG 10172 in acute stroke treatment-mediated stratification, which indicated that the AT1R rs1492099 T allele was linked to a decreased risk of large-artery atherosclerosis (LAA) stroke. We further found that those with the AT1R rs275653 AA genotype had a decreased risk of small-artery occlusion (SAO) strokes. We further confirmed elevated miR-155 expression in IS patients, but observed no link between the rs767649 polymorphism and expression of this microRNA. Similarly, rs1492099 and rs275653 polymorphisms did not impact AT1R expression levels. The miR-155 rs767649 polymorphism does not seem to be a key determinant of IS risk, whereas the AT1R rs1492099 polymorphism is linked to reduced LAA-stroke risk, and the rs275653 AA genotype is potentially protective against SAO strokes.

Sonographic evaluation of atherosclerosis burden in carotid arteries of ischemic stroke patients and its relation to paraoxonase 1 and 2, MTHFR and AT1R genetic variants

OBJECTIVE

Common variants of the Paraoxonase (PON), 5-Methyl-Tetrahydrofolate-Reductase (MTHFR) and Angiotensin-II receptor 1 (AT1R) genes have been associated with ischemic stroke (IS) risk. Moreover, carotid atherosclerosis is a common cause of IS. The aim of this study is to explore whether variants in these genes associate with the severity of ultrasonographic determined atherosclerosis assessed in carotid arteries.

PATIENTS AND METHODS

Etiologic subtype of cerebral ischemia was determined according to the TOAST classification. Genotypes were detected by PCR and restriction analysis. An ultrasonographic supra-aortic trunks study was performed to all patients to assess their atherosclerotic involvement based on predefined criteria.

RESULTS

In IS patients, none of the analyzed gene distributions differed concerning the stenosis degree. Nevertheless, a trend was observed for the rs662 and rs7493 variants of the PON1 and PON2 genes respectively. When evaluated the results based on different inheritance models, a significant contribution of rs7493 variant according to a dominant (OR=2.397, 95% CI (1.001-5.376); p=0.045) and log-additive inheritance forms (OR=1.85, 95% CI (1.07-3.2); p=0.03) was observed. Only rs7493 reached statistical significance (p=0.013), when genotype distribution was analyzed according to carotid intima-media thickness (cIMT) and remain significant in multivariate logistic regression analysis (OR=2.66, 95% CI (1.1 to 6.4); p=0.03).

CONCLUSION

In IS patients of the north area of the Gran Canaria island the PON2 (rs7493) gene variant associates with a worse ultrasonographic profile. Conversely, the Cys311Cys homozygosis of the rs7493 variant was also related to a better ultrasonographic profile in our study.

[Update on the genetics of stroke]

Stroke is a disease with significant morbidity, mortality, and economic and social impacts. It is a complex entity whose pathogenesis involves multiple environmental and genetic factors, with the latter having a role in up to 50% of strokes. The objective of the review is to analyze the available methods for the genetic diagnosis including linkage studies of variation in copy number, gene - candidate approximations, or whole genome (GWAS) and polymorphisms associated with its pathogenesis. We describe several single nucleotide polymorphisms (SNPs) associated with stroke in association studies and GWAS such as SNPs of angiotensin, the aldosterone system, paraoxonases, nitric oxide, coagulation, and fibrinolysis system, among others. We also analyze the role of certain polymorphisms in the phenotype of the carotid plaque, intracranial aneurysms and lobar hemorrhages. Pharmacogenomic aspects in which SNPs affect the response and safety regarding the use of different drugs are also described. Several SNPs that significantly contribute to the risk of stroke are also described. The advent of techniques like GWAS has contributed to the understanding of genetics and pharmacogenomics of stroke.

The AGTR1 gene A1166C polymorphism as a risk factor and outcome predictor of primary intracerebral and aneurysmal subarachnoid hemorrhages

Associations between the angiotensin II type 1 receptor (AGTR1) gene A1166C polymorphism and hypertension, aortic abdominal aneurysms (as a risk factor) as well as cardiovascular disorders (as a risk factor and an outcome predictor) have been demonstrated. We aimed to investigate the role of this polymorphism as risk factors and outcome predictors in primary intracerebral hemorrhage (PICH) and aneurysmal subarachnoid hemorrhage (aSAH). We have prospectively recruited 1078 Polish participants to the study: 261 PICH patients, 392 aSAH patients, and 425 unrelated control subjects. The A1166C AGTR1 gene polymorphism was studied using the tetra-primer ARMS-PCR method. Allele and genotype frequencies were compared with other ethnically different populations. The A1166C polymorphism was not associated with the risk of PICH or aSAH. Among the aSAH patients the AA genotype was associated with a good outcome, defined by a Glasgow Outcome Scale of 4 or 5 (p<0.02). The distribution of A1166C genotypes in our cohort did not differ from other white or other populations of European descent. In conclusion, we found an association between the A1166C AGTR1 polymorphism and outcome of aSAH patients, but not with the risk of PICH or aSAH.

Which risk factors are more associated with ischemic rather than hemorrhagic stroke in black Africans?

OBJECTIVE

To comprehensively examine the relationship of vascular risk factors to stroke type in native black Africans.

METHODS

We explored 34 candidate demographic, clinical, and laboratory variables in 282 consecutive adult stroke patients with brain imaging.

RESULTS

Ischemic stroke (IS) was found in 61.7% (174). Gender, alcohol, cigarette, homocysteine, C-reactive peptide, anthropometry, and carotid parameters were not significantly associated with stroke type (p>0.05). Patients with IS had relatively lower BP, were significantly older, and more frequently had diabetes mellitus, cardiac disease, or previous transient ischemic attack than patients with hemorrhagic stroke (HS). However, in multivariate regression model predicting 69% of stroke type correctly, age≥62 years (OR: 4.0, 95% CI: 2.0-7.9), previous TIA (OR: 4.3, 95% CI: 1.2-15.7) and systolic BP≥140 mmHg (OR: 0.4, 95% CI: 0.2-0.9) were the only independent significant predictors of IS.

CONCLUSIONS

With increasing proportion of the population over 61 years and better BP control, the proportion of IS is expected to rise in black African countries currently undergoing epidemiological transition (changing lifestyle/disease pattern). Therefore, relevant components of the stroke intervention quadrangle (stroke surveillance, acute care, preventive and rehabilitation services) should be tailored toward this need.

Lack of association of angiotensin II type 1 receptor A1166C gene polymorphism with the risk of end-stage renal disease

The association between angiotensin II type 1 receptor (AT1R) A 1166C (rs5186) gene polymorphism and end-stage renal disease (ESRD) risk remains controversial. We aimed to assess the association between AT1R A1166C gene polymorphism and ESRD susceptibility by performing a meta-analysis. Eligible studies were searched according to a predefined criterion using electronic databases. Eight articles were identified for the analysis of the association between AT1R A1166C gene polymorphism and ESRD risk. A allele and AA genotype were not associated with ESRD risk in overall populations, Caucasians and Asians (overall populations: p = 0.834 and 0.832, Caucasians: p = 0.853 and 0.884, Asians: p = 0.243 and 0.982). CC and AC genotype were not associated with ESRD risk in overall populations, Caucasians and Asians (overall populations: p = 0.304 and 0.712, Caucasians: p = 0.510 and 0.987, Asians: p = 0.319 and 0.225). In conclusion, AT1R A1166C gene polymorphism may not be correlated with ESRD risk in overall populations, Caucasians and Asians. However, more studies should be performed in the future.

Impact of angiotensin I converting enzyme insertion/deletion polymorphisms on dilated cardiomyopathy and hypertrophic cardiomyopathy risk

Background

Genetic factors in the pathogenesis of cardiomyopathies have received a lot attention during the past two decades. Angiotensin I converting enzyme (ACE) insertion/deletion (I/D) polymorphisms were found to be associated with cardiomyopathies. However, the previous results were inconsistent. The current meta-analysis aims to examine the association of ACE I/D polymorphisms and dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM).

Methods

Eight studies on DCM (1387 controls and 977 patients) and eight studies on HCM (1055 controls and 827 patients) were included in this meta-analysis.

Results

The overall data showed no significant association between ACE I/D polymorphism and DCM risk. Further subgroup analysis by ethnicity also did not find a significantly increased risk for D allele carriers among East Asians and Europeans. However, the overall analysis suggested that the D allele carriers might be associated with increased risk of HCM (DD/ID vs. II: OR = 1.69, 95% CI 1.04–2.74, P = 0.03).

Conclusion

In summary, the meta-analysis indicated that certain ACE I/D polymorphism might be associated with HCM but not DCM susceptibility. Given the limited sample sizes, further large multicenter case-control investigation is needed.