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

Stroke Demographics, Risk Factors, Subtypes, Syndromes, Mechanisms and Inter-Ethnic Differences between Chinese, Malays and Indians in Singapore-A Hospital-Based Study

Disparities in stroke may be due to socioeconomics, demographics, risk factors (RF) and ethnicity. Asian data are scant. This retrospective hospital-based study aimed to explore demographics, RF, stroke subtypes and mechanisms among the Chinese, Malays and Indians in Singapore. Stroke was subtyped into haemorrhagic stroke (HS) and ischaemic stroke (IS). For IS, the clinical syndrome was classified using the Oxfordshire Community Stroke Project (OCSP) classification while the stroke mechanism was categorised using the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification. During the study period 1 June 2015 to 31 December 2023, data were collected on 1165 patients, with a mean age of 65.6 ± 12.9 yr; 47.4% were female, 83% were Chinese and hypertension (63.5%) and hyperlipidaemia (60.3%) were the most common RF. HS comprised 23.5% (95%CI 21.1-26.1%) (intracerebral 21.7%, subarachnoid 1.3%) of the patients, while IS comprised 76.5% (95%CI 73.9-78.9%) (small artery occlusion 29.0%, cardioembolism 13.3%, large artery atherosclerosis 9.4%, stroke of other determined aetiology 6.2%, stroke of undetermined aetiology 18.6%); 55% of patients had lacunar syndrome. A multivariable analysis showed that HS was associated with ethnicity (p = 0.044), diabetes mellitus (OR 0.27, 95%CI 0.18-0.41, p < 0.001) and smoking (OR 0.47, 95%CI 0.34-0.64, p < 0.001). There were no significant inter-ethnic differences by the OCSP (p = 0.31) or TOAST (p = 0.103) classification. While differences in stroke subtype in Asia may be due to RF, ethnicity has a role. More studies are needed to further explore this.

Carotid atherosclerotic disease: A systematic review of pathogenesis and management

Carotid stenosis is an important contributor to ischemic stroke risk with resultant significant impact on neurological disability and death in adults and with worldwide implications. Management of carotid stenosis is impacted by whether there are associated symptoms along with the degree of stenosis. Understanding of the pathogenesis of carotid atherosclerosis or stenosis is important in management of carotid stenosis. Atherosclerotic plaque formation is a chronic insidious process with a number of potential contributors to the formation of such a plaque. The definition of atherosclerosis is not simply limited to abnormal deposition of lipid but also includes a chronic, complex, inflammatory process. Molecularly, in atherosclerosis, there is decreasing nitric oxide (NO) bioavailability, activity and/or expression of endothelial NO synthase, or increasing degradation of NO secondary to enhanced superoxide production. These above changes cause endothelial dysfunction leading to formation of foam cell followed by formation on lipid plaque. After lipid plaque formation, stable or unstable atherosclerotic plaque is formed depending on the calcium deposition over the lipid plaque. It continues to be clearly established that carotid intervention for symptomatic high-grade carotid stenosis is best managed with intervention either by carotid endarterectomy or carotid stenting. However, asymptomatic carotid stenosis is the subject of considerable controversy in terms of optimal management. This review of carotid atherosclerosis is an attempt to incorporate the information provided by more recent studies on pathogenesis and management which may help in the decision-making process for optimal management for protection against stroke.

Methylenetetrahydrofolate reductase polymorphism in healthy volunteers and its correlation with homocysteine levels in patients with thrombosis

OBJECTIVE:

To determine prevalence of methylenetetrahydrofolate reductase (MTHFR) mutations in apparently healthy individuals residing in Mumbai and patients with deep vein thrombosis (DVT) and coronary artery disease (CAD) and to correlate these polymorphisms with homocysteine (Hcy) levels.

MATERIALS AND METHODS:

This case–control study was initiated after receiving ethical approval and following the participant's written consent. One hundred and twenty unmatched healthy volunteers and 240 patients with arterial and venous thrombosis were enrolled. The prevalence of C677T and A1298C MTHFR mutations was detected using polymerase chain reaction-restriction fragment length polymorphism technique. Serum Hcy concentration and lipid levels were determined using biochemical kits.

RESULTS:

Allele frequency of 677T was 7%, 15%, and 14% in healthy controls, DVT, and CAD patients, respectively, while for 1298C allele, it was 31%, 33%, and 29%, respectively. The lipid markers in CAD patients were significantly low in comparison to the controls while the Hcy level in patients with thrombosis was higher in comparison with the controls. Highest Hcy levels were observed in participants with TT genotype followed by CT genotype and CC genotype in all the three groups. A higher risk of raised Hcy levels was seen in the variants (CT + TT) as compared to CC genotype in DVT (odds ratio [OR] = 3.39, 95% confidence interval [CI] = 1.39–8.2,P < 0.01) and CAD (OR = 21.67, 95%CI = 4.87–96.47,P < 0.0001). The risk observed for A1298C was 2.28 and 2.12 times higher in variants (AC + CC) of both DVT and CAD (OR = 2.28, 95%CI = 1.09–4.75 and OR = 2.12, 95%CI = 1.02–4.40, respectively).

CONCLUSIONS:

The prevalence of variants was more in thrombosis patients as compared to unmatched controls. Our study highlights the fact that MTHFR C677T polymorphism as compared to A1298C significantly affects Hcy levels in patients with thrombosis indicating that patients with mutant variants are at higher risk of rapid progression of their disease condition.

Vascular Genetic Variants and Ischemic Stroke Susceptibility in Albanians from the Republic of Macedonia

BACKGROUND

Acute first-ever ischemic stroke (FIS) is a heterogeneous, polygenic disorder. The contribution of vascular genetic variants as inherited causes of ischemic stroke has remained controversial.

AIM

To examine the association of genetic variants in vascular factors with the occurrence of FIS.

MATERIAL AND METHODS

The current research was performed in a group of 39 patients with FIS (study group) and 102 healthy volunteers (control group). We analyzed the prevalence of vascular genetic variants in following genes: factor V, prothrombin, methylenetetrahydrofolate reductase (MTHFR), factor XIII, plasminogen activator 1, endothelial protein C receptor (EPCR), apolipoprotein B, apolipoprotein E, β-fibrinogen, human platelet antigen 1, angiotensin-converting enzyme (ACE), endothelial nitric oxide synthase (eNOS) and lymphotoxin alpha.

RESULTS

It was found that heterozygous LTA 804C>A and FXIII V34L Leu/Leu were significantly more frequent in patients with FIS than in control group (p = 0.036 and p = 0.017, respectively). The frequency of FXIII V34L Val/Val was significantly lower in patients with FIS than in control group (p = 0.020). Other frequencies of vascular gene variants in patients with FIS and in control group were not significantly different.

CONCLUSIONS

This is the first comprehensive study to present data indicating that polymorphism of vascular genes in the prevalence of acute FIS exists in the Albanian population from the Republic of Macedonia. Variations in these genes have been detected in patients with acute FIS, suggesting that their combination might act in a susceptible or protective manner in this Albanian population.

Genetic susceptibility to cerebrovascular disease

PURPOSE OF REVIEW

Cerebrovascular disease (CeVD) remains a major cause of death and a leading cause of disability worldwide. CeVD is a complex and multifactorial disease caused by the interaction of vascular risk factors, environment, and genetic factors. In the present article, we discussed genetic susceptibility to CeVD, with particular emphasis on genetic studies of the associations between lipid traits and CeVD.

RECENT FINDINGS

Several animal and clinical studies clearly defined genetic predisposition to atherosclerosis and CeVD, and particularly to ischemic stroke. Recent evidence has shown that traditional vascular risk factors explain only a small proportion of variance in atherosclerosis, suggesting that additional nontraditional factors and novel genetic determinants impact CeVD. With the help of genome-wide technology, novel genetic variants have been implicated in CeVD and lipid metabolism such as those in protein convertase subtilisin/kexin type 9 (PCSK9) gene in stroke and familial hypercholesterolemia. These studies are important as they contribute to our understanding of the genetic mechanisms underlying CeVD and to developing more effective CeVD prevention strategies.

SUMMARY

CeVD is a complex and multifactorial disease and genetics likely plays an important role in its pathogenesis. The gene-gene and gene-environment interactions of genes involved in biology of vascular disease, including the lipid metabolism are important factors for individual susceptibility to CeVD. Accounting for individual variation in genes, environment and lifestyle will bring us closer to precision medicine, which is an emerging and recently introduced new approach for disease treatment and prevention in clinical practice.

Rare and Coding Region Genetic Variants Associated With Risk of Ischemic Stroke: The NHLBI Exome Sequence Project

IMPORTANCE

Stroke is the second leading cause of death and the third leading cause of years of life lost. Genetic factors contribute to stroke prevalence, and candidate gene and genome-wide association studies (GWAS) have identified variants associated with ischemic stroke risk. These variants often have small effects without obvious biological significance. Exome sequencing may discover predicted protein-altering variants with a potentially large effect on ischemic stroke risk.

OBJECTIVE

To investigate the contribution of rare and common genetic variants to ischemic stroke risk by targeting the protein-coding regions of the human genome.

DESIGN, SETTING, AND PARTICIPANTS

The National Heart, Lung, and Blood Institute (NHLBI) Exome Sequencing Project (ESP) analyzed approximately 6000 participants from numerous cohorts of European and African ancestry. For discovery, 365 cases of ischemic stroke (small-vessel and large-vessel subtypes) and 809 European ancestry controls were sequenced; for replication, 47 affected sibpairs concordant for stroke subtype and an African American case-control series were sequenced, with 1672 cases and 4509 European ancestry controls genotyped. The ESP's exome sequencing and genotyping started on January 1, 2010, and continued through June 30, 2012. Analyses were conducted on the full data set between July 12, 2012, and July 13, 2013.

MAIN OUTCOMES AND MEASURES

Discovery of new variants or genes contributing to ischemic stroke risk and subtype (primary analysis) and determination of support for protein-coding variants contributing to risk in previously published candidate genes (secondary analysis).

RESULTS

We identified 2 novel genes associated with an increased risk of ischemic stroke: a protein-coding variant in PDE4DIP (rs1778155; odds ratio, 2.15; P = 2.63 × 10(-8)) with an intracellular signal transduction mechanism and in ACOT4 (rs35724886; odds ratio, 2.04; P = 1.24 × 10(-7)) with a fatty acid metabolism; confirmation of PDE4DIP was observed in affected sibpair families with large-vessel stroke subtype and in African Americans. Replication of protein-coding variants in candidate genes was observed for 2 previously reported GWAS associations: ZFHX3 (cardioembolic stroke) and ABCA1 (large-vessel stroke).

CONCLUSIONS AND RELEVANCE

Exome sequencing discovered 2 novel genes and mechanisms, PDE4DIP and ACOT4, associated with increased risk for ischemic stroke. In addition, ZFHX3 and ABCA1 were discovered to have protein-coding variants associated with ischemic stroke. These results suggest that genetic variation in novel pathways contributes to ischemic stroke risk and serves as a target for prediction, prevention, and therapy.

Tumor necrosis factor beta NcoI polymorphism (rs909253) is associated with inflammatory and metabolic markers in acute ischemic stroke

Polymorphisms in genes coding for pro-inflammatory molecules represent important factors for the pathogenesis and outcome of stroke. The aim of this study was to evaluate the relationship between the tumor necrosis factor beta (TNF-β) NcoI (rs909253) polymorphism with inflammatory and metabolic markers in acute ischemic stroke. Ninety-three patients and 134 controls were included. The TNF-β polymorphism was determined using PCR-RFLP with NcoI restriction enzyme. Stroke subtypes and neurological deficit score were evaluated. White blood cell counts, erythrocyte sedimentation rate (ESR), plasma levels of IL-6 and TNF-α, serum high sensitivity C-reactive Protein (hsCRP), serum lipid profile, plasma levels of glucose and insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) were determined. Stroke patients presented higher white blood cell counts, hsCRP, ESR, glucose, insulin, and HOMA-IR, and lower HDL cholesterol than controls (p < 0.01). There was no difference in genotypic and allelic frequency of TNF-β NcoI polymorphism among patients and controls (p > 0.05). However, stroke patients carrying the TNFB2/B2 genotype presented higher levels of TNF-α, white blood cell counts, total cholesterol, LDL cholesterol, glucose, insulin, and HOMA-IR than those with other genotypes (p < 0.05). White blood cells, IL-6, hsCRP, and ESR were positively correlated with the neurological deficit of the patients (p < 0.05). Taken together, TNF-β NcoI polymorphism, by itself, was not associated with increased susceptibility for stroke development. However, the homozygous genotype for the allele TNFB2 was associated with higher expression of classical inflammatory and metabolic markers of development and outcome of stroke than other genotypes. The identification of variant alleles might allow both better prediction of susceptibility for stroke as well the identification of novel stroke mechanisms that could be target to new therapeutic approaches. Stroke patients carrying the TNFB2 variant allele could have a beneficial effect with the anti-inflammatory therapies in the early inflammatory phase of stroke.

A systematic appraisal of field synopses in genetic epidemiology: a HuGE review

Evidence from genetic association studies is accumulating rapidly. Field synopses have recently arisen as an unbiased way of systematically synthesizing this evidence. We performed a systematic review and appraisal of published field synopses in genetic epidemiology and assessed their main findings and methodological characteristics. We identified 61 eligible field synopses, published between January 1, 2007, and October 31, 2013, on 52 outcomes reporting 734 significant associations at the P < 0.05 level. The median odds ratio for these associations was 1.25 (interquartile range, 1.15-1.43). Egger's test was the most common method (n = 30 synopses) of assessing publication bias. Only 12 synopses (20%) used the Venice criteria to evaluate the epidemiologic credibility of their findings (n = 449 variants). Eleven synopses (18%) were accompanied by an online database that has been regularly updated. These synopses received more citations (P = 0.01) and needed a larger research team (P = 0.02) than synopses without an online database. Overall, field synopses are becoming a valuable tool for the identification of common genetic variants, especially when researchers follow relevant methodological guidelines. Our work provides a summary of the current status of the field synopses published to date and may help interested readers efficiently identify the online resources containing the relevant genetic evidence.

Meta-Analysis of the ACE Gene Polymorphism in Cerebral Infarction

Background:

The angiotensin-1 converting enzyme (ACE) gene is known to have two polymorphic alleles insertion/deletion(I/D). People with the DD genotype have been shown to be at greater risk of cerebral infarction, but only in some studies. Identification of cerebral infarction susceptibility genes and quantification of associated risks have been hampered by conflicting results from underpowered case-control studies. This meta-analysis was made to look specifically into the genetics of cerebral infarction among Han Chinese population.

Methods:

Genetic associations studies published from January 1, 1990 to December 30, 2007 were collected from databases of MEDLINE, EMBASE, CBM and CNKI. Data were extracted using standardised forms and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

Results:

Twenty-nine original case-control studies of Han Chinese population, comprising 3654 patients with cerebral infarction and 3058 controls were included in the meta-analysis. Using the random effects model, the pooled ORs of ACE DD genotype VS ID+ II was 1.91 (95% CI 1.56 to 2.34, P<0.00001).

Conclusions:

These data suggest that the ACE DD genotype may be a risk factor for cerebral infarction in Han Chinese population. A large scale case-control study is needed to clarify the functional effect of the polymorphism of the ACE I/D gene in the pathogenesis of cerebral infarction in Han Chinese population.

Association between the methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism and ischemic stroke in the Chinese population: a meta-analysis

PURPOSE

The association between the methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism and ischemic stroke (IS) has been extensively studied; however, the results from genetic association studies have been inconsistent even in the Chinese population. As far as we know, there was no previous meta-analysis concerning this association in the Chinese population. Therefore, the aim of our meta-analysis was to further evaluate the association in the Chinese population.

METHODS

We collected all of the relevant studies from Pubmed, OVID, Embase, Chinese Wan Fang database, CNKI, Chongqing VIP database and CBM up to August 2014. The available data was analyzed by Stata (version 12.0). We used odds ratios (ORs) and corresponding 95% confidence intervals (CIs) to present the strength of the association. Heterogeneity was evaluated by the Q-test and I(2) statistic. Different genetic models, subgroup analysis, publication bias and sensitivity analysis were used to improve the comprehensive understanding.

RESULTS

The results showed a significant association between the MTHFR gene C677T polymorphism and IS in six genetic models (additive model: OR = 1.34, 95%CI: 1.17 ∼ 1.54, p < 0.001; dominant model: OR = 1.44, 95% CI:1.26 ∼ 1.64, p < 0.001; recessive model: OR = 1.45, 95% CI: 1.15 ∼ 1.83, p = 0.001; heterozygote model: OR = 1.35, 95% CI: 1.18 ∼ 1.55, p < 0.001; homozygote model: OR = 1.80, 95% CI: 1.34 ∼ 2.41, p < 0.001; and allelic model: OR = 1.34, 95% CI: 1.17 ∼ 1.53, p < 0.001) based on the overall population, as well as subgroup analysis. In addition, the similar results were obtained in the sensitivity analysis based on studies with the high quality.

CONCLUSIONS

This meta-analysis presented a significant association between the MTHFR gene C677T polymorphism and IS, the T allele might be a risk factor for IS in the Chinese population.

Designing algorithms for determining significance of DNA missense changes

Humans differ from each other in their genomes by <1 %. This determines the difference in susceptibility to disease, phenotypes, and traits. Predominantly, when looking for causal disease mutations, protein-coding sequences are screened first since those have the highest probability of affecting the function of a protein. Recent technological advances have seen a rise in the number of experiments being conducted to study a variety of diseases from monogenic to complex traits. Several computational approaches have been developed to extract putative functional missense variants. In this chapter we review some of these approaches and describe a standard step-by-step procedure that can be used to classify variants for the purpose of clinical care. We also provide two examples demonstrating this approach, one for a patient with a dilated cardiomyopathy diagnosis, and the other for a patient with an unknown etiology undergoing whole-genome sequencing (WGS).

Association between angiotensin converting enzyme gene insertion/deletion polymorphism and ischemic stroke in north Indian population: a case-control study and meta-analysis

OBJECTIVE

The purpose of this case-control study was to determine the relationship between angiotensin converting enzyme (ACE) insertion/deletion polymorphism and serum ACE level in north Indian patients with ischemic stroke.

METHODS

In the present study, 224 ischemic stroke patients and 224 age- and sex-matched control participants were recruited. Genotyping was performed using polymerase chain reaction (PCR) method. Serum ACE levels were measured by colorimetric method. Our results were integrated with other reported studies from India for a meta-analysis.

RESULTS

We observed that DD genotypes were more frequently distributed in cases (32·6%) compared with controls (26·8%). Borderline significance was observed between DD genotype and risk of small vessel disease (SVD) stroke as compared to controls (OR, 1·9; 95% CI, 0·88-4·4; P value 0·09) assuming dominant model of inheritance. The mean ACE serum level in IU/l for II, ID, and DD genotypes were 17·1 ± 7·7, 26 ± 12·4, and 51·3 ± 21 (P value < 0·001) in cases and 16·5 ± 9·4, 26·8 ± 13, and 45·19 ± 18·3 (P value < 0·001) in controls, respectively.

DISCUSSION

The results of the study show lack of significant association between ACE insertion/deletion polymorphism and ischemic stroke, however, higher risk was observed with DD genotype in small vessel disease stroke, but with borderline significance. Meta-analysis of studies from India showed that DD genotype is associated with risk of ischemic stroke.

Apolipoprotein E polymorphisms and ischaemic stroke: a two-center Greek study

BACKGROUND AND PURPOSE

Apolipropotein E(apoE) is a plasma protein exhibiting three common isoforms (E2, E3, E4). Its involvement in lipoprotein metabolism may have an impact on stroke occurrence. As results in the literature are inconclusive further studies are needed to elucidate its role. Our objective was to study the role of apoE isoforms and the interplay with environmental risk factors in patients with first ischaemic stroke occurrence in the Greek population.

METHODS

Three hundred and twenty-nine patients with first-ever ischaemic stroke were included in our study. Strokes of cardioembolic origin and patients with autoimmune or prothrombotic syndromes were excluded. A control group of 361 subjects with no stroke history were also included in our study. Risk factors (hyperlipidemia, hypertension, diabetes mellitus and smoking) were assessed. ApoE alleles were determined in all subjects participating in the study.

RESULTS

Genotype ε3/ε3 was found to have a protective role against stroke occurrence compared with other genotypes (odds ratio 0.674, 95% confidence interval 0.480-0.946) especially in the female patient subgroup. In multivariate analysis after adjustment for age, body mass index (BMI), hypertension, dyslipidemia, diabetes mellitus and smoking, the role of genotype was limited and outweighed by risk factors in both genders. No association between apoE alleles and BMI, cholesterol, triglycerides or high-density lipoprotein plasma levels was noted.

CONCLUSIONS

Our study was indicative of a protective role of the ε3/ε3 genotype, especially in female patients. However, risk factors such as age, BMI, hypertension, dyslipidemia, diabetes mellitus and smoking have a strong impact on stroke occurrence and outweigh the protective role of the ε3/ε3 genotype.

Genetics of ischaemic stroke

Recent advances in genomics and statistical computation have allowed us to begin addressing the genetic basis of stroke at a molecular level. These advances are at the cusp of making important changes to clinical practice of some monogenic forms of stroke and, in the future, are likely to revolutionise the care provided to these patients. In this review we summarise the state of knowledge in ischaemic stroke genetics particularly in the context of how a practicing clinician can best use this knowledge.

Association of the APOE, MTHFR and ACE Genes Polymorphisms and Stroke in Zambian Patients

The aim of the present study was to investigate the association of APOE, MTHFR and ACE polymorphisms with stroke in the Zambian population. We analyzed 41 stroke patients and 116 control subjects all of Zambian origin for associations between the genotype of the APOE, MTHFR and ACE polymorphisms and stroke. The APOE ε2ε4 genotype showed increased risk for hemorrhagic stroke (P<0.05) and also a high risk for ischemic stroke (P=0.05). There was complete absence of the APOE ε2ε2 and the MTHFR TT genotypes in the Zambian population. The difference between cases and controls was not significant for the other genetic variants when analyzed for relationship between stroke, stroke subtype and genotype. We show that genetic variation at the APOE locus affects susceptibility to stroke. No detectable association were observed for the MTHFR and ACE genotypes and stroke in the Zambian population.

BRG1 variant rs1122608 on chromosome 19p13.2 confers protection against stroke and regulates expression of pre-mRNA-splicing factor SFRS3

A single nucleotide polymorphism (SNP) rs1122608 on chromosome 19p13.2 and in the BRG1/SMARCA4 gene was previously associated with coronary artery disease (CAD). CAD and ischemic stroke are both associated with atherosclerosis. Thus, we tested the hypothesis that rs1122608 is associated with ischemic stroke. Further studies were used to identify the most likely mechanism by which rs1122608 regulates atherosclerosis. For case-control association studies, two independent Chinese Han GeneID cohorts were used, including a Central cohort with 1,075 cases and 2,685 controls and the Northern cohort with 1,208 cases and 824 controls. eQTL and real-time RT-PCR analyses were used to identify the potential candidate gene(s) affected by rs1122608. The minor allele T of SNP rs1122608 showed significant association with a decreased risk of ischemic stroke in the Central GeneID cohort (adjusted P adj = 2.1 × 10(-4), OR 0.61). The association was replicated in an independent Northern GeneID cohort (P adj = 6.00 × 10(-3), OR 0.69). The association became more significant in the combined population (P adj = 7.86 × 10(-5), OR 0.73). Allele T of SNP rs1122608 also showed significant association with a decreased total cholesterol level (P adj = 0.013). Allele T of rs1122608 was associated with an increased expression level of SFRS3 encoding an mRNA splicing regulator, but not with the expression of BRG1/SMARCA4 or LDLR (located 36 kb from rs1122608). Increased expression of SFSR3 may decrease IL-1β expression and secretion, resulting in reduced risk of atherosclerosis and stroke. This is the first study that demonstrates that rs1122608 confers protection against ischemic stroke and implicates splicing factor SFSR3 in the disease process.

Association of oxysterol binding protein-related protein 9 polymorphism with cerebral infarction in Hunan Han population

BACKGROUND

Oxysterol binding protein-related protein 9 (ORP9) may be related to the pathogenesis of cerebral infarction since it is closely related with glucose and lipid metabolism. The present study was designed to investigate the genetic relationship between ORP9 gene polymorphisms and cerebral infarction (CI) in Hunan Han population.

METHODS

Total 544 cerebral infarction patients (60.0 ± 10.3 years) and 284 healthy controls (59.0 ± 9.5 years) were enrolled. Sociodemographic and clinical data of the subjects, such as age, gender, body mass index, smoking, drinking, diabetes mellitus, hypertension, systolic and diastolic blood pressures, fasting blood glucose, triglycerides, total cholesterol, low-density and high-density lipoprotein were recorded, and two single-nucleotide polymorphisms (SNPs) of ORP9 gene including rs856600 and rs768529 with high mutation annotation format (MAF) values of 0.103 and 0.485 were studied by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

No statistical difference was observed in allele distributions and frequencies of the two SNPs between control and CI groups. However, the percentage of atherosclerosis in CI group was significantly higher than that in the control group (p < 0.001). The frequencies of the TT genotype and T allele of rs768529 were significantly higher in patients with vulnerable plaque than those in patients with stable plaque (p < 0.001, p = 0.002). Logistic association analysis showed no correlations between cerebral infarction and different alleles (p > 0.05).

CONCLUSION

T allele of rs768529 may be a risk factor for the formation of the carotid vulnerable plaque in Chinese Hunan Han population.

The role of classic risk factors and prothrombotic factor gene mutations in ischemic stroke risk development in young and middle-aged individuals

BACKGROUND

In young individuals, a genetically predisposing hypercoagulability and classic modifying risk factors can act synergistically on the ischemic stroke risk development. The aim of the study was to compare the prevalence of classic vascular risk factors and polymorphisms of the G20210A coagulation factor II (prothrombin), Arg506Glu coagulation factor V Leiden, C677T methylenetetrahydrofolate reductase (MTHFR), and 4G/5G plasminogen activator inhibitor-1 (PAI-1) and the impact of these gene mutations and classic vascular risk factors on the overall stroke risk in individuals aged 55 years or younger.

METHODS

The study included 155 stroke patients aged 55 years or younger and 150 control subjects. Stroke prevalence and odds ratio (OR) were assessed for the following parameters: G20210A prothrombin, Arg506Glu factor V Leiden, C677T MTHFR, and 4G/5G PAI-1 polymorphisms; total number of study polymorphisms in a particular subject (genetic sum); and classic vascular risk factors of hypertension, obesity, diabetes mellitus, cigarette smoking, hypercholesterolemia, hypertriglyceridemia, and elevated levels of low-density lipoprotein (LDL) cholesterol and very low-density lipoprotein cholesterol.

RESULTS

The prevalence of hypertension (P < .001), smoking (P < .001), decreased HDL cholesterol levels (P < .001), obesity (P = .001), elevated LDL cholesterol (P = .036), C677T MTHFR polymorphism (P < .001), and genetic sum was significantly higher in the group of stroke patients. The following parameters were found to act as independent risk factors for ischemic stroke: decreased HDL cholesterol level (P < .001; OR 4.618; 95% confidence interval [CI] 2.381-8.957); hypertension (P = .001; OR 2.839; 95% CI 1.519-5.305); obesity (P = .040; OR 2.148; 95% CI 1.036-4.457); smoking (P = .001; OR 2.502; 95% CI 1.436-4.359); and genetic sum as a continuous variable (P < .01; OR 2.307; 95% CI 1.638-3.250).

CONCLUSIONS

Gene mutations of the procoagulable and proatherosclerotic factors investigated exerted a synergistic action in the development of overall risk of ischemic stroke in young and middle-aged individuals.

Two novel susceptibility SNPs for ischemic stroke using exome sequencing in Chinese Han population

Genome-wide association studies (GWAS) of ischemic stroke (IS) have been performed on several cohorts of Caucasian or African population and Japanese, resulting in somewhat inconsistent conclusion. We aimed to identify susceptibility loci for IS by exome sequencing in a Chinese Han population. Exome sequencing was used to screen susceptibility loci among 100 cases and 100 matched controls. Significant SNPs from the first stage were verified in up to 3,554 participants from three hospital-based case-control studies. In the initial exome sequencing analysis, rs10489177 in c1orf156 gene located on chromosome 1q24 (p < 1 × 10(-8)) and rs17118 in XYLB gene located on chromosome 3p21 (p < 1 × 10(-6)) were found to be significantly associated with IS. In the following validation stage, significantly increased odds ratios were observed in individuals with rs10489177 GG (OR = 2.02, 95 % CI = 1.35-3.03) or rs17118 AA genotype (OR = 1.50, 95 % CI = 1.17-1.91). The rs10489177 GG genotype was associated with significantly increased risk for IS in individuals without hypertension (OR = 2.78, 95 % CI = 1.59-4.86) and in individuals without diabetes (OR = 1.93, 95 % CI = 1.27-2.94). In contrast, the rs17118 AA genotype may significantly increase the risk for IS, particularly for individuals with hypertension (OR = 1.73, 95 % CI = 1.08-2.78) and for individuals without diabetes (OR = 1.52, 95 % CI = 1.17-1.98) or non-smoker (OR = 1.59, 95 % CI = 1.16-2.19). Collectively, our study identified two novel loci (rs17118 and rs10489177) which were associated with an increased risk for IS in Chinese Han populations. Further studies are needed to confirm these associations in other populations and elucidate the biological mechanisms underlying the observed associations.

Association of pregnancy-associated plasma protein-A gene polymorphism with ischemic stroke in northern Chinese Han population

OBJECTIVES

The pregnancy-associated plasma protein-A (PAPP-A), belonging to the metalloproteinase superfamily, plays an important role in destabilization of atherosclerotic plaques. The aim of this study is to evaluate whether PAPP-A gene polymorphism is associated with the risk of ischemic stroke (IS) in northern Chinese Han populations.

METHODS

A total of 368 patients with IS and 374 aged-matched healthy controls in a Chinese Han population were included in the case-control study. The single-nucleotide polymorphism (SNP) IVS6+95 (rs13290387) in the PAPP-A gene was analyzed by the polymerase chain reaction-ligation detection reaction (PCR-LDR) method.

RESULTS

Compared with the GG+CG genotype, the frequencies of the CC genotype of IVS6+95 (rs13290387) in the patients with IS were significantly higher than those in the controls (P  =  0·026). After adjusting the confounding risk factors of IS (age, gender, smoking, alcohol drinking, hypertension, diabetes mellitus, and hyperlipidemia) by the multivariate logistic analysis, this significant correlation still remained (P  =  0·010).

DISCUSSION

The CC genotype of IVS6+95 (rs13290387) was associated with increased incidence of IS in northern Chinese Han populations. This is an initial study to indicate that PAPP-A (rs13290387) might contribute to IS susceptibility in northern Chinese Han populations.

Association of nNOS gene polymorphism with ischemic stroke in Han Chinese of North China

Nitric oxide (NO) is an important messenger molecule and effector molecule. This study aimed to investigate the relation of neuronal nitric oxide synthase (nNOS) gene polymorphism with ischemic stroke in Han Chinese of North China. This was a case-control study. A total of 413 patients with ischemic stroke were recruited from Han Chinese of North China. There were 201 males and 212 females. In addition, 477 healthy subjects served as controls including 224 males and 253 females. Multiplex SNaPshot was employed to detect nNOS gene polymorphism (rs2293050, rs2139733, rs7308402, and rs1483757). Results showed that the rs1483757, rs2139733, and rs2293050 genotypes and allele frequencies were comparable between patients and controls. However, ischemic stroke patients had significantly reduced AG genotype and A allele frequency when compared with controls (P = 0.037, P = 0.041). After adjusting confounding factors (gender, age, smoking, history of drinking, hypertension, and diabetes), AG genotype and A allele were still related to ischemic stroke (OR = 0.572, 95% CI: 0.335–0.978, P = 0.041; OR = 0.611, 95% C: 0.378–0.985, and P = 0.041) and both were found to be protective factors. Our results showed that rs7308402 gene polymorphism of nNOS is related to ischemic stroke in Han Chinese of North China.

Significant association between angiotensin-converting enzyme gene insertion/deletion polymorphism and risk of recurrent miscarriage: a systematic review and meta-analysis

BACKGROUND

Many studies have investigated the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and risk of recurrent miscarriage, but the impact is unclear due to inconsistencies among those studies. This study aimed to quantify the strength of the association between ACE I/D polymorphism and recurrent miscarriage risk by performing a systematic review and meta-analysis.

DESIGN AND METHODS

We searched PubMed, Embase, Web of Science, and Wanfang Medicine databases for eligible articles relating the association between ACE I/D polymorphism and risk of recurrent miscarriage in humans. We estimated the summary odds ratios (ORs) with their 95% confidence intervals (95% CIs) to assess the association.

RESULTS

Eleven studies with a total of 3357 individuals were included in this meta-analysis. Compared to the ACE II genotype, DD and ID were both associated with increased risk of recurrent miscarriage (OR DD versus II=1.81, 95% CI 1.23-2.66, P=0.003; OR ID versus II=1.50, 95% CI 1.25-1.80, P<0.001). Sensitivity analyses further confirmed the association above. No evidence of publication bias was observed.

CONCLUSION

Meta-analyses of available data show a significant association between ACE I/D polymorphism and recurrent miscarriage risk, and the ACE polymorphic D allele contributes to increased risk of recurrent miscarriage.

Lack of association between a functional variant of the BRCA-1 related associated protein (BRAP) gene and ischemic stroke

Background

Atherosclerosis shares common pathogenic features with myocardial infarction (MI) and ischemic stroke. BRCA-1 associated protein (BRAP), a newly identified risk gene for MI, aggravates the inflammatory response in atherosclerosis. The aim of this study was to test the association between the BRAP gene and stroke in a Taiwanese population.

Methods

A total of 1,074 stroke patients and 1,936 controls were genotyped for the functional SNP rs11066001. In our previous studies, the rare allele of this SNP has been repeatedly shown to exert a recessive effect. Therefore, in the current study, we tested for the same recessive model. First, the genotype distributions between all the controls and all the stroke cases were compared. Then to reduce heterogeneity, we explored several population subsets by selecting young stroke subjects (using 45 years of age as the cutoff point), age- and sex-comparable controls, plaque-free controls, and stroke subtypes.

Results

We did not find any significant association for the entire data set (OR = 0.94, p = 0.74) or for the subset analyses using age- and sex-comparable controls (p = 0.70) and plaque-free controls (p = 0.91). Analyses of the four stroke subtypes also failed to show any significant associations (p = 0.42 – 0.98). For both young and old subjects, the GG genotype of rs11066001 was similar in the stroke cases and unmatched controls (8.1% vs. 9.4% in young subjects and 8.0% vs. 7.8% in old subjects). Comparing stroke cases with plaque-free controls also failed to find any significant association.

Conclusions

The BRAP polymorphism may not play an important role in ischemic stroke in the studied population.

South Asians have elevated postexercise blood pressure and myocardial oxygen consumption compared to Europeans despite equivalent resting pressure

Background

Stroke mortality rate is higher in South Asians than in Europeans, despite equivalent or lower resting blood pressure (BP). Elevated recovery BP after exercise predicts stroke, independently of resting values. We hypothesized that South Asians would have adverse postexercise hemodynamics and sought explanations for this.

Methods and Results

A population-based sample of 147 European and 145 South Asian middle-aged men and women performed the Dundee 3-minute step test. Cardiovascular risk factors were measured. BP, heart rate, and rate–pressure product, a measure of myocardial oxygen consumption, were compared. With 90% power and 5% significance, we could detect a difference of 0.38 of a standard deviation in any outcome measure. Resting systolic BP was similar in South Asians (144 mm Hg) and Europeans (142 mm Hg) (P=0.2), as was exercise BP (P=0.4). However, recovery systolic BP at 3 minutes after exercise was higher in South Asians by 4.3 mm Hg (95% confidence interval [CI], 0.2 to 8.3 mm Hg; P=0.04). This effect persisted when adjusted for exercise BP and work effort (5.4 mm Hg [95% CI, 2.2 to 8.7 mm Hg; P=0.001]). Adjustment for baroreflex insensitivity and greater aortic stiffness in South Asians contributes greatly to attenuating this ethnic difference (1.9 mm Hg [95% CI, −0.9 to 4.6 mm Hg; P=0.4]). Similarly, rate–pressure product recovery after exercise was impaired in South Asians by 735 mm Hg/min (95% CI, 137 to 1334 mm Hg/min; P=0.02); again, adjustment for baroreflex insensitivity and aortic stiffness attenuated this difference (261 mm Hg/min [95% CI, −39 to 561 mm Hg/min; P=0.3]).

Conclusion

Postexercise recovery of BP and rate–pressure product is impaired in South Asians compared to Europeans even though resting and exercise BP are similar. This is associated with the autonomic dysfunction and aortic stiffness in South Asians. (J Am Heart Assoc. 2012;1:e000281 doi: 10.1161/JAHA.111.000281.)

Association between the apolipoprotein E gene polymorphism and ischemic stroke in Chinese populations: New data and meta-analysis

Ischemic stroke (IS) is a complex multifactorial inherited disease. Many studies have focused on the potential genetic effects of apolipoprotein E (ApoE) gene polymorphism on IS. However, inconsistencies still exist in the association of ApoE gene polymorphism with IS. The aim of this study was to investigate the ApoE gene polymorphism in relation to IS in the Guangxi Han populations and assess the risk of various ApoE genotypes associated with IS in Chinese populations. We conducted a case-control study involving a total of 166 IS cases and 192 healthy controls to investigate the association of ApoE gene polymorphism with IS in the Guangxi Han populations. Furthermore, we performed a meta-analysis to investigate whether the ApoE gene polymorphism is associated with IS in Chinese populations. There was no evidence for a significant association between ApoE gene polymorphism and IS in the Guangxi Han populations (ɛ2/ɛ2 vs. ɛ3/ɛ3: OR=1.25, 95% CI=0.08–20.17; ɛ2/ɛ3 vs. ɛ3/ɛ3: OR=1.49, 95% CI=0.79–2.79; ɛ2/ɛ4 vs. ɛ3/ɛ3: OR=1.25, 95% CI=0.17–9.00; ɛ3/ɛ4 vs. ɛ3/ɛ3: OR=1.10, 95% CI=0.60–2.04; ɛ4/ɛ4 vs. ɛ3/ɛ3: OR=2.50, 95% CI=0.22–27.87; allele ɛ2 vs. allele ɛ3: OR=1.39, 95% CI=0.80–2.44; allele ɛ4 vs. allele ɛ3: OR=1.16, 95% CI=0.68–1.98). In our meta-analysis, a significant association of ApoE gene polymorphism with IS was found in the genetic model of ɛ2/ɛ4 vs. ɛ3/ɛ3 (OR=2.04, 95% CI=1.45–2.85), ɛ3/ɛ4 vs. ɛ3/ɛ3 (OR=1.93, 95% CI=1.42–2.62), ɛ4/ɛ4 vs. ɛ3/ɛ3 (OR=3.41, 95% CI=2.17–5.34) and allele ɛ4 vs. allele ɛ3 (OR=2.34, 95% CI=1.91–2.86). However, no clear associations were found in the model of ɛ2/ɛ2 vs. ɛ3/ɛ3 (OR=1.56, 95% CI=0.90–2.71), ɛ2/ɛ3 vs. ɛ3/ɛ3 (OR=0.93, 95% CI=0.79–1.09) and allele ɛ2 vs. allele ɛ3 (OR=1.10, 95% CI=0.97–1.25). In conclusion, no association was found between ApoE gene polymorphism and IS in the Guangxi Han populations, while the results of the meta-analysis indicate that the ApoE mutation allele ɛ4 increases the risk of IS in Chinese populations.

Large-scale meta-analysis of genetic studies in ischemic stroke: Five genes involving 152,797 individuals

BACKGROUND:

Ischemic stroke descent has a genetic basis. Stroke represents a complex trait, which is assumed to be polygenic. On this topic, the role of a wide number of candidate genes has been investigated in stroke through association studies.

MATERIALS AND METHODS:

We performed a literature-based systematic review of genetic association studies in stroke abound several populations. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined for each gene-disease association. Following a review of 300 manuscripts, five candidate gene variants were analyzed among 152,797 individuals (45,433 cases and 107,364 controls).

RESULTS:

For these five candidate genes studied, the prothrombin OR is 1,57 (1,23-2,89), the factor V Leiden OR is 1,43 (0,67-6,24), the mean OR of angiotensin I converting enzyme (ACE) insertion/deletion (I/D) polymorphism is 1,11 (1,02-1,25), the summary OR for the C677T variant of 5,10-methylenetetrahydrofolate reductase (MTHFR) is 1,23 (0,61-1,47) and the pooled OR for the apolipoprotein E (APOE) gene is 0,95 (0,77-1,14) .

CONCLUSION:

These data suggest the genetic associations of some genes with ischemic stroke and it is necessary to compete with other genes. Our findings could represent an epidemiological base and a useful tool to address further molecular investigations and to realize more detailed meta-analyses.

Angiotensin-converting enzyme insertion/deletion polymorphism contributes to ischemic stroke risk: a meta-analysis of 50 case-control studies

Background

Many studies have investigated the association between the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and risk of ischemic stroke. However, the evidence is inadequate to draw robust conclusions because most studies were generally small and conducted in heterogeneous populations. To shed light on these inconclusive findings, we conducted a large meta-analysis of studies relating the ACE I/D polymorphism to the risk of ischemic stroke.

Methods

Relevant studies were identified by searching PubMed and Embase through February 2012 and by reviewing the references of retrieved articles. We included studies that reported odds ratio (OR) with 95% confidence interval (CI) for the association between this polymorphism and ischemic stroke risk.

Results

Fifty independent publications, with 10 070 stroke cases and 22 103 controls, were included. The results indicated that the DD homozygote carriers had a 37% higher risk of ischemic stroke when compared with the homozygotes II and heterozygote ID [odds ratio (OR) = 1.37, 95% confidence interval (CI): 1.22–1.53]. Subgroup analyses indicated that this higher risk was more pronounced among Asians, hospital-based studies, and small vessel disease (SVD). Potential publication bias may exist, but correction for this bias using a formal statistical method did not materially alter the combined risk estimate.

Conclusion

The results of our meta-analysis indicate that the D allele of ACE I/D polymorphism is a low-penetrance susceptibility marker of ischemic stroke.

Novel association of a PROC variant with ischemic stroke in a Chinese Han population

Protein C (PC) is a well-characterized anticoagulant enzyme. However, the association between PC and ischemic stroke (IS) remains controversial. The aim of the present study was to investigate whether any genetic variant in the human protein C gene (PROC) was associated with susceptibility to IS in the Chinese Han population. All exons and the 5'- and 3'-untranslated regions of PROC were initially sequenced to identify informative variants. Potential abnormal variants were analyzed in a population of 788 IS patients and 1,200 healthy controls. The analysis was stratified by stroke etiology, and the results were replicated in 262 IS patients and 288 healthy controls. Finally, functional studies were performed to evaluate the effects of the variant. A three-nucleotide duplication/deletion variant (c.574_576del) was identified and found to be significantly associated with IS (OR 2.56, 95 % CI 1.45-4.52, P = 0.001). Stratification by stroke etiology after adjustment for IS risk factors showed that this association persisted in the lacunar and cardioembolic subtypes (P < 0.001 and P = 0.008, respectively) but not in the atherothrombotic and undetermined subtypes (P = 0.070 and P = 0.998, respectively). The functional studies showed a significant difference in the anticoagulant activity of PC in c.574_576del carriers and non-carriers (P < 0.001). Our results suggested that the novel PROC c.574_576del variant is a possible genetic determinant of an increased risk of IS and diminished anticoagulant activity of PC.

The Influence of Stroke Risk Factors and Comorbidities on Assessment of Stroke Therapies in Humans and Animals

The main driving force behind the assessment of novel pharmacological agents in animal models of stroke is to deliver new drugs to treat the human disease rather than to increase knowledge of stroke pathophysiology. There are numerous animal models of the ischaemic process and it appears that the same processes operate in humans. Yet, despite these similarities, the drugs that appear effective in animal models have not worked in clinical trials. To date, tissue plasminogen activator is the only drug that has been successfully used at the bedside in hyperacute stroke management. Several reasons have been put forth to explain this, but the failure to consider comorbidities and risk factors common in older people is an important one. In this article, we review the impact of the risk factors most studied in animal models of acute stroke and highlight the parallels with human stroke, and, where possible, their influence on evaluation of therapeutic strategies.

Free-floating thrombus of the carotid artery with a homozygous methylenetetrahydrofolate reductase gene mutation: a case report

Free-floating thrombus (FFT) of the carotid artery is a rare condition of currently unknown etiology. We describe a symptomatic patient with an FFT in the left common carotid artery. A duplex ultrasonography scan showed the presence of a mobile floating thrombus moving in cyclical motion with the cardiac cycles in the left common carotid artery. During emergency surgery, an FFT was seen at this location and removed. No underlying wall defect was seen at the time of surgery. In a genetic screening test, TT homozygous for the methylenetetrahydrofolate reductase (MTHFR) C677T genetic polymorphisms was detected. The patient recovered uneventfully, with no neurogical events. Lifelong anticoagulant therapy was recommended. An aggressive surgical approach is recommended in the patient to prevent embolic episodes.

Prothrombotic gene variants and mortality after cerebral ischemia of arterial origin

BACKGROUND

Several functional prothrombotic gene variants have been associated with cerebral ischemia and myocardial infarction. We hypothesized that such gene variants may also be associated with mortality after cerebral ischemia of arterial origin because of an increased risk of fatal vascular events.

METHODS

We performed a case-control study in 316 long-term survivors and 887 patients with recent cerebral ischemia of arterial origin. False discovery rate q values were calculated to account for multiple testing. The mean duration between occurrence of cerebral ischemia and DNA collection was 16.8 years in long-term survivors and 3.2 months in recent patients.

RESULTS

Two of 23 variants were associated with mortality: the 95Arg allele of the coagulation factor XIII subunit B (F13B) His95Arg variant (OR, 1.5 for Arg/Arg and His/Arg vs. His/His genotype; 95% CI, 1.1-2.2, q = 0.29) and the 4G allele of the plasminogen activator inhibitor-1 (PAI-1) 4G/5G variant (OR, 1.5 for 4G/4G and 5G/4G vs. 5G/5G genotype; 95% CI, 1.1-2.0, q = 0.29). Both associations disappeared after accounting for multiple testing. Data analysis restricted to recently deceased patients (n = 133) yielded similar results.

CONCLUSIONS

In this hospital-based study none of 23 prothrombotic gene variants were associated with long-term mortality after cerebral ischemia of arterial origin. Prothrombotic gene variants do not appear to play an important role in long-term mortality after cerebral ischemia.

Multilocus analyses of seven candidate genes suggest interacting pathways for obesity-related traits in Brazilian populations

We investigated whether variants in major candidate genes for food intake and body weight regulation contribute to obesity-related traits under a multilocus perspective. We studied 375 Brazilian subjects from partially isolated African-derived populations (quilombos). Seven variants displaying conflicting results in previous reports and supposedly implicated in the susceptibility of obesity-related phenotypes were investigated: β2-adrenergic receptor (ADRB2) (Arg16Gly), insulin induced gene 2 (INSIG2) (rs7566605), leptin (LEP) (A19G), LEP receptor (LEPR) (Gln223Arg), perilipin (PLIN) (6209T > C), peroxisome proliferator-activated receptor-γ (PPARG) (Pro12Ala), and resistin (RETN) (-420 C > G). Regression models as well as generalized multifactor dimensionality reduction (GMDR) were employed to test the contribution of individual effects and higher-order interactions to BMI and waist-hip ratio (WHR) variation and risk of overweight/obesity. The best multilocus association signal identified in the quilombos was further examined in an independent sample of 334 Brazilian subjects of European ancestry. In quilombos, only the PPARG polymorphism displayed significant individual effects (WHR variation, P = 0.028). No association was observed either with the risk of overweight/obesity (BMI ≥ 25 kg/m2), risk of obesity alone (BMI ≥ 30 kg/m2) or BMI variation. However, GMDR analyses revealed an interaction between the LEPR and ADRB2 polymorphisms (P = 0.009) as well as a third-order effect involving the latter two variants plus INSIG2 (P = 0.034) with overweight/obesity. Assessment of the LEPR-ADRB2 interaction in the second sample indicated a marginally significant association (P = 0.0724), which was further verified to be limited to men (P = 0.0118). Together, our findings suggest evidence for a two-locus interaction between the LEPR Gln223Arg and ADRB2 Arg16Gly variants in the risk of overweight/obesity, and highlight further the importance of multilocus effects in the genetic component of obesity.

Genetic susceptibility to ischemic stroke

Clinicians who treat patients with stroke need to be aware of several single-gene disorders that have ischemic stroke as a major feature, including sickle cell disease, Fabry disease, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, and retinal vasculopathy with cerebral leukodystrophy. The reported genome-wide association studies of ischemic stroke and several related phenotypes (for example, ischemic white matter disease) have shown that no single common genetic variant imparts major risk. Larger studies with samples numbering in the thousands are ongoing to identify common variants with smaller effects on risk. Pharmacogenomic studies have uncovered genetic determinants of response to warfarin, statins and clopidogrel. Despite increasing knowledge of stroke genetics, incorporating this new knowledge into clinical practice remains a challenge. The goals of this article are to review common single-gene disorders relevant to ischemic stroke, summarize the status of candidate gene and genome-wide studies aimed at discovering genetic stroke risk factors, and to briefly discuss pharmacogenomics related to stroke treatment.

Bio-Repository of DNA in stroke (BRAINS): a study protocol

Background

Stroke is one of the commonest causes of mortality in the world and anticipated to be an increasing burden to the developing world. Stroke has a genetic basis and identifying those genes may not only help us define the mechanisms that cause stroke but also identify novel therapeutic targets. However, large scale highly phenotyped DNA repositories are required in order for this to be achieved.

Methods

The proposed Bio-Repository of DNA in Stroke (BRAINS) will recruit all subtypes of stroke as well as controls from two different continents, Europe and Asia. Subjects recruited from the UK will include stroke patients of European ancestry as well as British South Asians. Stroke subjects from South Asia will be recruited from India and Sri Lanka. South Asian cases will also have control subjects recruited.

Discussion

We describe a study protocol to establish a large and highly characterized stroke biobank in those of European and South Asian descent. With different ethnic populations being recruited, BRAINS has the ability to compare and contrast genetic risk factors between those of differing ancestral descent as well as those who migrate into different environments.

Genes associated with adult cerebral venous thrombosis

BACKGROUND AND PURPOSE

Quantitative predictions of the risk of cerebral venous thrombosis (CVT) conferred by certain genotypes have yet to be reliably established. We conducted a comprehensive meta-analysis of all candidate genes studied to assess their genetic contribution to the etiology of CVT. We compared our findings against equivalent analyses for pediatric CVT and adult ischemic stroke.

METHODS

Databases were searched to August 2010 for all genes investigated in adult CVT, and odds ratios (ORs) for each gene-disease association were calculated. A mendelian randomization strategy was also undertaken to determine whether a causal relation to one gene could be ascertained.

RESULTS

We identified 26 case-control studies investigating 6 polymorphisms in 6 genes and included 1183 CVT cases and 5189 controls. Statistically significant associations with CVT were found for factor V Leiden/G1691A (OR=2.40; 95% CI, 1.75 to 3.30; P<0.00001) and prothrombin/G20210A (OR=5.48; 95% CI, 3.88 to 7.74; P<0.00001). After iterative analysis controlling for interstudy heterogeneity, methylene tetrahydrofolate reductase/C677T was also found to be significantly associated (OR=2.30; 95% CI, 1.20 to 4.42; P=0.02). Variants in the remaining 3 genes (Janus kinase-2, plasminogen activator inhibitor-1, and protein Z) were not significantly associated. Pooled ORs for CVT risk in adults for factor V Leiden and prothrombin were significantly greater when compared against childhood CVT and adult arterial ischemic stroke. A causal relation with methylene tetrahydrofolate reductase may exist.

CONCLUSIONS

CVT has a genetic basis. Genes involved in the clotting cascade provide a greater level of thrombosis risk in the cerebral venous circulation compared with its arterial circulation, and a greater level of risk exists for adults compared with children.

Angiotensin I - Converting Enzyme Gene Polymorphism and Activity in Patients with Ischemic Stroke

The possible association of ACE polymorphism with ischemic stroke (IS) was evaluated in 65 patients with IS and 330 age and BMI-matched controls. ACE genotypes were determined by polymerase chain reaction (PCR). There was no significant difference in ACE genotype/allele frequencies between case and control group (p>0.05). Patients with D allele had 4,7 times higher risk for large vessel IS than healthy persons D allele possessors. Persons with D allele had 9.2 times higher risk for large vessel disease than small vessel disease. These data suggest a possible association of ACE gene polymorphism with pathogenesis of large vessel IS.

CYP4F2 gene V433M polymorphism is associated with ischemic stroke in the male Northern Chinese Han population

BACKGROUND

CYP4F2 is a member of the cytochrome P450 enzymes and is responsible for metabolizing arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE); 20-HETE plays a role in the regulation of vascular tone in the cerebral, coronary, and renal circulation. The present study aimed to evaluate whether or not the CYP4F2 gene polymorphism V433M (rs2108622) is involved in ischemic stroke in the Northern Chinese Han population.

METHODS

In a case-control study, the participants included 302 (193 males and 109 females) patients with ischemic stroke and 350 (212 males and 138 females) healthy subjects. The V433M polymorphism of the CYP4F2 gene was analyzed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) with the restriction enzyme PvuII.

RESULTS

The frequencies of the GG genotype and the G allele were higher in participants with ischemic stroke than in the control group (P=0.018). Multiple logistic regression analysis revealed the significance of the rs2108622 in males after adjustment for confounding factors. No difference was found in all participants and females.

CONCLUSION

The GG genotype and G allele were associated with ischemic stroke in the male Northern Chinese Han population.