Polymorphism of angiotensin-converting enzyme, angiotensinogen, and apolipoprotein E genes in Korean patients with cerebral infarction

Apolipoprotein E Gene Polymorphism Effects on Lipid Metabolism and Risk of Cerebral Infarction in Northwest Han Chinese Population

Background

The apolipoprotein E (ApoE) genetic variation may contribute to the development of Cerebral Infarction (CI). Serum lipid levels are known risk factors for CI, but the effect of the ApoE gene polymorphism on lipid metabolism remains unclear. This retrospective cohort study was designed to determine the role of ApoE genotypes in CI risk and the relationships between ApoE gene polymorphism and serum lipid levels among the population of northwest China.

Patients and Methods

517 CI patients and 517 non-CI controls were enrolled in the study. Polymerase chain reaction and hybridization were utilized to determine the ApoE gene polymorphisms.

Results

The ε3/ε4 genotype and ε4 allele frequency were significantly higher in CI patients than in controls. When stratified by age and sex, statistically significant differences in the distribution and frequency of the ε3/ε4 genotype and ε4 allele were found between patients and controls. Compared to ε2 carriers, ε4 carriers had significantly lower ApoE levels and higher low-density lipoprotein cholesterol (LDL-C), ApoB and ApoB/ApoA-I levels in both two groups. Additionally, control participants with ε4 carriers had significantly higher levels of lipoprotein and total cholesterol (TC) levels than ε2 carriers, while CI patients with ε4 carriers had a significantly lower level of ApoA-I. After adjusting for other established risk factors, drinking, hypertension, lipoprotein, triglycerides (TG) and ε4 allele were significant independent risk factors for CI, which was shown to be associated with a nearly two-fold CI risk.

Conclusion

This study demonstrated that ε4 allele is independent risk factors for CI among patients in Northwest China. ApoE polymorphism was associated with CI, which was partly mediated through blood lipids and may also be mediated through non-lipid pathways. These data might be of great clinical significance in individualized preventive and therapeutic strategies.

Association between Apolipoprotein ε4 Gene Polymorphism and Risk of Ischemic Stroke: A Meta-Analysis

BACKGROUND

Previous studies examining the association of apolipoprotein E (APOE) gene polymorphism with the risk of ischemic stroke (IS) have yielded conflicting results. Therefore, we performed a meta-analysis to investigate the association between APOE ε4 gene polymorphism and risk of IS.

SUMMARY

A literature search for genetic association studies published before May 30, 2015, was conducted in the PubMed, EMBASE and Google Scholar databases. The following search terms were used: (apolipoprotein E) or (APOE) and (ε4) and (polymorphism) or (polymorphisms) and ('ischemic stroke' or 'IS') and ('cerebral infarction' or 'CI') and ('genetic polymorphism' or 'single nucleotide polymorphisms' or 'SNP'). ORs and 95% CIs were used to calculate the strength of association. Begg's funnel plot was used to assess the potential for publication bias. In our meta-analysis, 26 case-control studies involving 6,397 IS cases and 19,053 controls were included. Overall significant association between carrier of ε4 allele and risk of IS was observed (OR 1.43, 95% CI 1.10-1.85, p = 0.007). In the subgroup analysis based on ethnicity, a significant association between Apo ε4 carrier and risk of IS was observed in Asian studies (OR 1.53, 95% CI 1.04-2.25, p = 0.031) whereas borderline significant association between APO ε4 carrier and risk of IS was observed in Caucasian studies (OR 1.36, 95% CI 0.95-1.93, p = 0.093).

KEY MESSAGES

Our meta-analysis suggests that APOE ε4 allele is associated with higher risk of IS in Asian population as compared to Caucasian population.

[Association of T174M polymorphism of the angiotensinogen gene with the higher risk of cerebral stroke in women]

AIM

To study the association of M235T (rs699) and T174M (rs4762) polymorphisms of the angiotensinogen (AGT) gene with the risk of cerebral stroke (CS) in the Russians of the Central Chernozem Region.

MATERIALS AND METHODS

A total of 638 DNA samples obtained from 353 patients with CS and 285 sex- and age-matched healthy individuals were examined. The polymorphisms were genotyped by polymerase chain reaction (T174M) and TaqMan allelic discrimination (M235T) assays.

RESULTS

Heterozygous AGT 174TM genotype carriers were found to be at a higher risk for CS (odd ratio (OR) = 1.52; 95% confidence interval (CI), 1.08-2.15; p = 0.02). A gender-stratified analysis showed that the mutant 174M allele (OR = 1.86; 95% CI, 1.14-3.03, p = 0.01) and variant 174TM and 174MM genotypes (OR = 1.86; 95% CI, 1.09-3.20; p = 0.02) were associated with the higher risk of cerebral stroke in women.

CONCLUSION

The association of AGT T174M polymorphism with the risk of CS was first found; but the higher risk of the disease in the carriers of variant alleles and genotypes was observed in the women only.

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.

Assessment of two missense polymorphisms (rs4762 and rs699) of the angiotensinogen gene and stroke

The renin-angiotensin system has an important role in the pathogenesis of stroke. We investigated whether two missense single nucleotide polymorphisms (SNPs; rs4762, Thr207Met, T207M; and rs699, Met268Thr, M268T) of angiotensinogen (AGT; serpin peptidase inhibitor, clade A, member 8) are associated with the development and clinical phenotypes of ischemic stroke (IS) and intracerebral hemorrhage (ICH). We analyzed 197 stroke patients (120 IS and 77 ICH) and 301 control subjects. The patients were classified into subgroups in accordance to the scores of the National Institutes of Health Stroke Survey (NIHSS, <6 and ≥6) and Modified Barthel Index (MBI, <60 and ≥60). Multiple logistic regression models were used to analyze the genotype and allele distributions of each SNP. One of the missense SNPs, rs4762 (T207M) was associated with the development of ICH (P=0.038 in log-additive model and P=0.021 in allele distributions). The T allele frequency of T207M was higher in the ICH group (16.2%) compared with the control group (9.6%). The TC haplotype frequency differed significantly between the ICH and control groups (P=0.014). With regard to clinical features, T207M correlated with the NIHSS scores of the ICH patients (P=0.039 in codominant1, P=0.015 in dominant, P=0.011 in overdominant and P=0.039 in log-additive models). However, the two missense SNPs, rs4762 and rs699, were not associated with IS and its clinical features, including NIHSS and MBI scores. These data suggest that a missense SNP (rs4762, T207M) of the AGT gene may be associated with the development of ICH and contribute to the neurological functional levels of ICH patients.

Synergistic effects of ACE (I/D) and ApoE (HhaI) gene polymorphisms among the adult Asian Indians with and without metabolic syndrome

A total of 350 (184 males and 166 females) adults participated in the study. A sample of 138 individuals was selected randomly for genotyping. The synergistic effect of ACE (I/D) and ApoE (HhaI) on metabolic syndrome (MS) showed that individuals with e4/4+D/D combination had the highest occurrence of metabolic abnormalities.

Association between renin-angiotensin-aldosterone system genotypes and haplotypes and risk of ischemic stroke of atherosclerotic etiology

OBJECTIVE

The association of renin C-4063T and angiotensinogen (AGT) T174M, AGT M235T and AGT A-6G polymorphisms with ischemic stroke of atherosclerotic etiology was investigated in 329 Tunisian patients with stroke and 444 controls.

MATERIALS AND METHODS

Genotyping was performed using PCR-RFLP and the contributions of polymorphisms to the risk of stroke were analyzed using haplotype and multivariate regression analysis.

RESULTS

AGT 235T and AGT-6G allele and AGT 235T/T, AGT-6A/G and AGT-6G/G genotype frequencies were higher in patients. Linkage disequilibrium (LD) was noted for AGT174T with AGT235M and AGT(-6)A in patients, while AGT235M was in LD with AGT(-6)A in controls and AGT235T was in LD with AGT(-6)G in both groups. The AGT 174T/235T/-6A and AGT 174T/235M/-6G haplotypes were positively and negatively associated with stroke respectively. Multivariate regression analysis identified AGT 174T/235M/-6A, AGT 174T/235T/-6G, AGT 174T/235T/-6A and AGT 174M/235T/-6A haplotypes to be significantly associated with an increased risk of stroke.

CONCLUSIONS

Renin-angiotensin-aldosterone system polymorphisms influence the risk of atherosclerotic stroke in Tunisians.

Interaction of angiotensin-converting enzyme and apolipoprotein E gene polymorphisms in ischemic stroke involving large-vessel disease

A relationship between apolipoprotein E (Apo E) genotype and angiotensin-converting enzyme (ACE) insertion-deletion (Ins-Del) mutation and stroke was suggested. We investigated the association of Apo E4 and ACE Ins/Del genotypes with stroke risk and changes in serum lipids in 228 consecutive Tunisian stroke patients, and 323 age-and gender-matched controls. Comparable frequencies of ACE Ins/Del alleles were seen between patients and controls. The prevalence of Apo epsilon3 allele and Apo E3/E3 were lower (P < 0.001), while the frequency of Apo epsilon4 allele and epsilon4-containing genotypes (E3/E4 and E4/E4) were elevated (P < 0.001) among patients. Higher proportion of Apo E4-carrying + ACE Del/Del positive cases were seen in young (<50 years) patients (P = 0.012), and was associated with large vessel stroke (P = 0.035). Mean serum cholesterol, LDL, HDL, and triglycerides were comparable between E4-containing and no E4-containing and ACE Del/Del-positive patients. Apo E4 and ACE Del/Del genotype combination substantially increase stroke risk, supporting the notion that interactions of multiple gene variants influence stroke pathogenesis.

Polymorphisms of the renin-angiotensin system are associated with blood pressure, atherosclerosis and cerebral white matter pathology

BACKGROUND

The renin-angiotensin system is involved in the development of hypertension, atherosclerosis and cardiovascular disease. We studied the association between the M235T polymorphism of the angiotensinogen gene (AGT) and the C573T polymorphism of the angiotensin II type 1 receptor (AT1R) and blood pressure, carotid atherosclerosis and cerebrovascular disease.

METHODS

We genotyped over 6000 subjects from the Rotterdam Study and more than 1000 subjects from the Rotterdam Scan Study. We used logistic regression and univariate analyses, adjusting for age and sex with, for AGT, the MM and, for AT1R, the TT genotype as reference.

RESULTS

We found that AGT-235T increased systolic (p for trend = 0.03) and diastolic blood pressure (p for trend = 0.04). The prevalence of carotid plaques was increased 1.25-fold (95% CI 1.02-1.52) in AGT-TT carriers. There was a significant increase in mean volume deep subcortical white matter lesions (WML) for AGT-TT carriers (1.78 ml vs 1.09 ml in the reference group; p = 0.008). A significant interaction was found between AGT and AT1R, further increasing the effect on periventricular and subtotal WML (p for interaction = 0.02). We found a non-significant increased risk of silent brain infarction for AGT-TT carriers and AT1R-CC carriers, but no effect on stroke.

CONCLUSION

We found an association between AGT and blood pressure, atherosclerosis and WML. Also, we found synergistic effects between AGT and AT1R on the development of WML. These findings raise the question of whether the renin-angiotensin system may be a therapeutic target for the prevention of cerebral white matter pathology.

Polymorphism of apolipoprotein E (APOE) and lipoprotein lipase (LPL) genes and ischaemic stroke in individuals of Yakut ethnicity

There is evidence that most forms of ischaemic stroke (IS) result from synergistic effects of the modifiable predisposing factors and multiple genes. In the present work, we report results of case-control study of IS association with apolipoprotein E gene (APOE) (promoter and coding polymorphisms) and lipoprotein lipase gene (LPL) (presence/absence of a HindIII cutting site). We studied 107 unrelated patients of Yakut ethnicity (69 men and 38 women, mean age 58.4+/-11.5 years) with first-ever IS in carotid/middle cerebral artery regions. The control group included 101 subjects of the same ethnicity (61 men and 40 women, mean age 57.6+/-11.6 years) free of clinically detectable cerebrovascular disease, and without any history of stroke. A positive association of IS with APOE -427T allele (p=0.0012, OR=3.99) and -427T/T genotype (p=0.0005, OR=4.96) and a negative association with -427C allele (p=0.0012, OR=0.25), -427T/C genotype (p=0.0003, OR=0.18), epsilon2 allele (p=0.018, OR=0.35), epsilon2/3 genotype (p=0.017, OR=0.28) and -491A/-427C/epsilon2 haplotype (p=0.0026, OR=0.18) were observed. For atherothrombotic subgroup the same allele and genotype associations were found plus association with APOE -491A allele (p=0.026, OR=3.98). No reliable IS associations were found with LPL T+495G (HindIII) polymorphism. An association of APOE promoter polymorphisms (A-491T, T-427C) with an IS is shown in our study for the first time. Our study provides evidence for the role of APOE gene as a prognostic genetic marker for IS, especially for its atherothrombotic subtype.

Genetics of ischaemic stroke among persons of non-European descent: a meta-analysis of eight genes involving approximately 32,500 individuals

BACKGROUND

Ischaemic stroke in persons of European descent has a genetic basis, but whether the stroke-susceptibility alleles, the strength of any association, and the extent of their attributable risks are the same in persons of non-European descent remains unanswered. Whether ethnicity itself has a relevant or substantial contribution on those effect estimates is controversial. Comparative analyses between the ethnic groups may allow general conclusions to be drawn about polygenic disorders.

METHODS AND FINDINGS

We performed a literature-based systematic review of genetic association studies in stroke in persons of non-European descent. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined for each gene-disease association using fixed and random effect models. We further performed a comparative genetic analysis across the different ethnic groups (including persons of European descent derived from our previous meta-analysis) to determine if genetic risks varied by ethnicity. Following a review of 500 manuscripts, eight candidate gene variants were analysed among 32,431 individuals (12,883 cases and 19,548 controls), comprising mainly Chinese, Japanese, and Korean individuals. Of the eight candidate genes studied, three were associated with ischaemic stroke: the angiotensin I converting enzyme (ACE) insertion/deletion (I/D) polymorphism with a mean OR of 1.90 (95% CI 1.23-2.93) in the Chinese and 1.74 (95% CI 0.88-3.42) in the Japanese; the summary OR for the C677T variant of 5,10-methylenetetrahydrofolate reductase (MTHFR) was 1.18 (95% CI 0.90-1.56) in Chinese and 1.34 (95% CI 0.87-2.06) in Koreans; and the pooled OR for the apolipoprotein E (APOE) gene was 2.18 (95% CI 1.52-3.13) in Chinese and 1.51 (95% CI 0.93-2.45) in Japanese. Comparing the commonly investigated stroke genes among the Asian groups against studies in persons of European descent, we found an absence of any substantial qualitative or quantitative interaction for ORs by ethnicity. However, the number of individuals recruited per study in the studies of persons of non-European descent was significantly smaller compared to studies of persons of European descent, despite a similar number of studies conducted per gene.

CONCLUSIONS

These data suggest that genetic associations studied to date for ischaemic stroke among persons of non-European descent are similar to those for persons of European descent. Claims of differences in genetic effects among different ethnic populations for complex disorders such as stroke may be overstated. However, due to the limited number of gene variants evaluated, the relatively smaller number of individuals included in the meta-analyses of persons of non-European descent in stroke, and the possibility of publication bias, the existence of allele variants with differential effects by ethnicity cannot be excluded.

Association of gene polymorphism with genetic susceptibility to stroke in Asian populations: a meta-analysis

Stroke is a heterogeneous multifactorial disease and is thought to have a polygenic basis. Case-control studies on gene sequence variations have identified a number of potential genetic predisposition factors, but due to the conflicting results, uncertainty remains on the effect of these polymorphisms on risk for the development of stroke. To qualitatively and quantitatively assess the risk associated with different gene polymorphisms for stroke in Asian populations, we comprehensively searched and identified all the studies of association. Clinically overt case-control studies were selected only if neuroimaging had been used as the confirmatory measure for diagnosis of stroke. We performed a meta-analysis of the three most investigated genes, viz., methylenetetrahydrofolate reductase (MTHFR), apolipoprotein E (ApoE) and angiotensin-converting enzyme (ACE). Statistically significant association with stroke were identified for C677T polymorphism of MTHFR [random effects odds ratio (OR) = 1.47, 95% confidence interval (95% CI) 1.19, 1.82; P = 0.0004] and marginally significant association was detected with allele epsilon 4 of ApoE (random effects OR = 1.47, 95% CI 1.00, 2.15; P = 0.049). The sensitivity analysis (exclusion of studies with controls not in Hardy-Weinberg equilibrium) revealed a significant association of stroke with the MTHFR C677T and ApoE epsilon 4 alleles but showed no association with ACE gene insertion/deletion polymorphism.

Angiotensin II type-1 receptor A1166C polymorphism is associated with increased risk of ischemic stroke in hypertensive smokers

Recent observations revealed a novel role of angiotensin-converting enzyme 2 and the angiotensin II type-1 receptor (AT1R) in lung injury, thereby extending knowledge about the functions of the angiotensin system. Angiotensin II, whose target is the AT1R, is a potent vasoconstrictor. Accordingly, an imbalance leading to enhanced activity of the angiotensin II-AT1R axis is postulated to contribute to both circulatory disturbances and lung injury. In this context, a functional single-nucleotide polymorphism, AT1R A1166C, which leads to enhanced responsiveness of the AT1R, has been postulated as a candidate susceptibility factor for ischemic stroke. The aim of our study was to investigate its occurrence in ischemic stroke and to analyze its possible synergistic associations with clinical risk factors. Genetic and clinical data on 308 consecutive patients with acutely developing ischemic stroke were analyzed. A total of 272 stroke and neuroimaging alteration-free subjects served as a control group. Univariate and logistic regression statistical approaches were used. Alone, the AT1R 1166C allele did not pose a risk of stroke. In hypertensive smokers, however, it was associated with an increased risk of ischemic stroke (OR 22.3, 95% CI 5.8-110.2, p<0.001). Further subgroup analysis revealed the same association for both small-vessel (OR 24.3, 95% CI 6.1-121.1, p<0.001) and large-vessel (OR 21.3, 95% CI 4.6-81.1, p<0.001) infarction. On a pathophysiological basis, our results suggest the possibility that the AT1R A1166C polymorphism might give rise to ischemic stroke indirectly via an unfavorable effect on the cardiorespiratory function.

The genetics of stroke

PURPOSE OF REVIEW

Ischaemic stroke is a heterogeneous disease caused by different pathogenic mechanisms, of which small artery and large artery stroke are the most common. The identification of the genes involved is unclear. The likely candidate genes associated with stroke are those that are associated with matrix deposition (stromelysin-1, MMP3), inflammation (IL-6), and lipid metabolism (hepatic lipase, APOE, PON1) and clotting (factor V Leiden, fibrinogen).

RECENT FINDINGS

In this review we will only discuss those genes in which there has been a significant contribution to the understanding of stroke since October 2003.

SUMMARY

The published data were reviewed to determine the robustness of these associations and to examine whether there is any evidence of risk modification by factors such as smoking habit, known to be associated with stroke.

TNF-alpha and TNF-beta gene polymorphisms in cerebral infarction

Tumor necrosis factor (TNF) is an important cytokine in the inflammation process of atherosclerosis. Two biallelic polymorphisms in the TNF-alpha (TNF-alpha -308) and TNF-beta (TNF-beta +252) genes have been reported to be associated with TNF production and susceptibility to inflammatory diseases. We investigated two genetic polymorphisms in the TNF locus (TNF-alpha -308 G-->A and TNF-beta +252 A-->G) as risk factors for cerebral infarction (CI) by determining its prevalence in 294 survivors of CI, and in 581 age-, gender-, and race-matched controls. A significant association was found for the TNF-alpha and TNF-beta genotypes in CI patients compared with controls. A significant increase was found for the TNF-alpha A allele in controls compared with CI patients (chi2 = 7.593, p = 0.006, odds ratio = 1.74, confidence interval = 1.17-2.59). In addition, the TNF-alpha GG genotype increased the relative risk for CI in subjects with the TNF-beta AA genotype (chi2 = 4.998, p = 0.025). As a result, compared to controls, the frequency of the TNF-alpha AA genotype was decreased, whereas that of TNF-beta AA was increased in CI patients. The former implies an association with resistance, whereas the latter suggests an association with susceptibility to the disease. These results show that the TNF-alpha -308 and TNF-beta +252 locus plays an important role in the etiopathogenesis of CI.