Genetic risk factors for stroke and carotid atherosclerosis: insights into pathophysiology from candidate gene approaches

Exploring the bi-directional relationship and shared genes between depression and stroke via NHANES and bioinformatic analysis

Background: Stroke and depression are the two most common causes of disability worldwide. Growing evidence suggests a bi-directional relationship between stroke and depression, whereas the molecular mechanisms underlying stroke and depression are not well understood. The objectives of this study were to identify hub genes and biological pathways related to the pathogenesis of ischemic stroke (IS) and major depressive disorder (MDD) and to evaluate the infiltration of immune cells in both disorders. Methods: Participants from the United States National Health and Nutritional Examination Survey (NHANES) 2005-2018 were included to evaluate the association between stroke and MDD. Two differentially expressed genes (DEGs) sets extracted from GSE98793 and GSE16561 datasets were intersected to generate common DEGs, which were further screened out in cytoHubba to identify hub genes. GO, KEGG, Metascape, GeneMANIA, NetworkAnalyst, and DGIdb were used for functional enrichment, pathway analysis, regulatory network analysis, and candidate drugs analysis. ssGSEA algorithm was used to analyze the immune infiltration. Results: Among the 29706 participants from NHANES 2005-2018, stroke was significantly associated with MDD (OR = 2.79,95% CI:2.26-3.43, p < 0.0001). A total of 41 common upregulated genes and eight common downregulated genes were finally identified between IS and MDD. Enrichment analysis revealed that the shared genes were mainly involved in immune response and immune-related pathways. A protein-protein interaction (PPI) was constructed, from which ten (CD163, AEG1, IRAK3, S100A12, HP, PGLYRP1, CEACAM8, MPO, LCN2, and DEFA4) were screened. In addition, gene-miRNAs, transcription factor-gene interactions, and protein-drug interactions coregulatory networks with hub genes were also identified. Finally, we observed that the innate immunity was activated while acquired immunity was suppressed in both disorders. Conclusion: We successfully identified the ten hub shared genes linking the IS and MDD and constructed the regulatory networks for them that could serve as novel targeted therapy for the comorbidities.

Differential expression of non-coding RNAs and association with cerebral ischemic vascular disorders; diagnostic and therapeutic opportunities

BACKGROUND

Over the last few decades, research associated with the coding genome, primarily DNA and transcriptome (mRNA, rRNA, and tRNA), has changed our understanding in several aspects, including physiology, diagnostics, and therapeutics. A large proportion of the human genome that encodes proteins is essential for physiology. However, the human genome represents a significantly large proportion of non-translational, i.e., non-coding (nc) RNAs like microRNAs, siRNAs, piRNAs, lncRNAs, and circRNAs. These ncRNAs do not translate into functional proteins but are associated with several events, such as the regulation of gene expression via several mechanisms. Our understanding of ncRNAs has advanced in the last decade, such as microRNAs and siRNAs, but still, several other ncRNAs remain unexplored. The study comprehended the association of ncRNAs in cerebral ischemia.

METHODS

In this study searches utilizing multiple databases, PubMed, EMBASE, and Google Scholar were made. The literature survey was done on ncRNA including short and lncRNA associated with the onset, and progression of cerebral ischemia. The literature search was also made for the studies associated with the diagnostic and therapeutic role of ncRNAs for cerebral ischemia.

RESULTS AND DISCUSSION

Reports suggested that both short and long ncRNAs are critical players of gene expression and are hence associated with the pathophysiology of cerebral ischemia. The reports demonstrate ncRNAs precisely lncRNAs and microRNAs are not only associated with cerebral ischemia progression but also potential diagnostic and therapeutic candidates.

IN CONCLUSION

This review is certainly helpful to understand the interplay of ncRNAs in understanding gene expression profile and pathophysiology of cerebral ischemia. These ncRNAs molecules show potential for diagnostic and therapeutic development.

Genetic association of ANRIL with susceptibility to Ischemic stroke: A comprehensive meta-analysis

Background

Ischemic stroke (IS) is a complex polygenic disease with a strong genetic background. The relationship between the ANRIL (antisense non-coding RNA in the INK4 locus) in chromosome 9p21 region and IS has been reported across populations worldwide; however, these studies have yielded inconsistent results. The aim of this study is to clarify the types of single-nucleotide polymorphisms on the ANRIL locus associated with susceptibility to IS using meta-analysis and comprehensively assess the strength of the association.

Methods

Relevant studies were identified by comprehensive and systematic literature searches. The quality of each study was assessed using the Newcastle-Ottawa Scale. Allele and genotype frequencies were extracted from each of the included studies. Odds ratios with corresponding 95% confidence intervals of combined analyses were calculated under three genetic models (allele frequency comparison, dominant model, and recessive model) using a random-effects or fixed-effects model. Heterogeneity was tested using the chi-square test based on the Cochran Q statistic and I2 metric, and subgroup analyses and a meta-regression model were used to explore sources of heterogeneity. The correction for multiple testing used the false discovery rate method proposed by Benjamini and Hochberg. The assessment of publication bias employed funnel plots and Egger’s test.

Results

We identified 25 studies (15 SNPs, involving a total of 11,527 cases and 12,216 controls maximum) and performed a meta-analysis. Eight SNPs (rs10757274, rs10757278, rs2383206, rs1333040, rs1333049, rs1537378, rs4977574, and rs1004638) in ANRIL were significantly associated with IS risk. Six of these SNPs (rs10757274, rs10757278, rs2383206, rs1333040, rs1537378, and rs4977574) had a significant relationship to the large artery atherosclerosis subtype of IS. Two SNPs (rs2383206 and rs4977574) were associated with IS mainly in Asians, and three SNPs (rs10757274, rs1333040, and rs1333049) were associated with susceptibility to IS mainly in Caucasians. Sensitivity analyses confirmed the reliability of the original results. Ethnicity and individual studies may be the main sources of heterogeneity in ANRIL.

Conclusions

Our results suggest that some single-nucleotide polymorphisms on the ANRIL locus may be associated with IS risk. Future studies with larger sample numbers are necessary to confirm this result. Additional functional analyses of causal effects of these polymorphisms on IS subtypes are also essential.

PON1 (Paraoxonase 1) Q192R gene polymorphism in ischemic stroke among North Indian population

Background:

PON1 is an High Density Lipoprotein (HDL)-associated esterase. Two common polymorphisms in the PON1 gene, Q192R and L55M substitutions, determine the inter-individual variation in PON1 activity. The association of these polymorphisms with the risk of ischemic stroke remains controversial. In the present study, the role of PON1 Q192R gene polymorphism in ischemic stroke was studied in the Indian population.

Design and Methods:

In the present case-control study, the PON1 Q192R gene polymorphism was screened in ischemic stroke patients (n: 63) and age, sex-matched controls (n: 63) using thePolymerase Chain Reaction-Restriction Segment Length Polymorphism (PCR-RFLP) method.

Results:

The mean age of stroke presentation was 58.11 ± 15.4 years. A total of 17.4% cases presented with young stroke (<45 years age) and 9.52% cases were seen to have a recurrent stroke. The distribution of -192Q/R PON1 gene polymorphism was not seen to differ between cases and controls. The traditional stroke risk factors did not have any effect on the PON1 genotype expression. A multivariate logistic regression analysis was done in order to assess an independent association of age, gender, traditional stroke risk factors, and PON1 polymorphism with acute ischemic stroke. However, neither the RR genotype nor the presence of the R allele was associated with an increase in the risk of acute ischemic stroke (OR [RR genotype]-4.76, P value: 0.24, 95% CI: 0.3497–64.8531; OR [R allele]-0.94, P value: 0.90, 95% CI: 0.3516–2.4989).

Conclusion:

PON1 Q192R gene polymorphism is not associated with an increased risk of acute ischemic stroke in the North Indian population. Further studies with a larger sample size are needed before PON1 Q192R gene polymorphism can be considered as a genetic risk factor for ischemic stroke.

Gene polymorphism in tissue epidermal growth factor receptor (EGFR) influences clinical and histological vulnerability of carotid plaques

INTRODUCTION

Different models have been proposed for the prediction of the risk/benefit ratio of surgery in patients with carotid atheromasic disease, mainly based on clinical patients' characteristics and risk factors, but no definite biological markers predictive of plaque instability and disease evolution have emerged so far, able to help the surgeon in the choice and timing of treatment. The main purpose of the present study was to assess the role of the polymorphism for genes commonly implicated in cell proliferation and neoangiogenesis in the clinical and histopathological carotid plaque vulnerability.

MATERIALS AND METHODS

We retrospectively studied 29 consecutive patients who underwent carotid endarterectomy in 6 months. All histological variables were collected, as well as patients' cardiovascular risk factors, clinical presentation, and brain computed tomography (CT) for the presence of ischemic lesions. Next-Generation Sequencing (NGS) was performed on 10-µm FFPE sections by means of a multi-gene panel used for sequencing 343 amplicons in 28 genes.

RESULTS

Among the gene variants observed, the polymorphism p.(Gln787=) in the EGFR gene was inversely correlated with intraplaque hemorrhage (p = 0.014), but also with the presence of ischemic brain lesions at CT (p = 0.001). Also p.(Gly105=) polymorphism in the IDH1 gene was inversely correlated with the presence of ischemic brain lesions (p = 0.038).

CONCLUSIONS

The variant p.(Gln787=) in the EGFR gene seems to play a role in plaque stability in patients with carotid atheromasic disease, on both histopathological and clinical grounds, probably acting on plaque matrix remodeling. This can open new scenarios on the pre-surgical management of these patients.

Susceptibility of PON1/PON2 Genetic Variations to Ischemic Stroke Risk in a Chinese Han Population

Background

Paraoxonases (PONs) are a family of orphan enzymes with multiple functions, including anti-inflammatory, antioxidative, antiatherogenic activities. Studies have suggested that genetic variations in PON1 and PON2 are associated with ischemic stroke (IS) risk; however, the conclusion remains unclear in the Chinese population.

Methods

To investigate the susceptibility of genetic variations in PON1 and PON2 to risk of IS and its subtypes, this case–control study was carried out on a Chinese population comprising 300 IS patients and 300 healthy controls. Genotypes of six genetic variations in PON1 and PON2 were identified with an improved multiplex ligase detection–reaction technique.

Results

PON1 rs662 was associated with increased risk of IS (CT vs. TT — OR_adjusted 1.79, 95% CI 1.08–2.97; p=0.025). Stratified analysis for patients by sex revealed that the significant association of PON1 rs662 with IS risk was maintained in the male cohort (CT vs. TT — OR_adjusted 2.59, 95% CI 1.29–5.21 [p=0.009]; CT/CC vs. TT — OR_adjusted 2.03, 95% CI 1.05–3.93 [p=0.036]), but not in the female cohort. Analysis according to IS subtype revealed that PON1 rs662 genetic variation was an increased risk in the subcohort of patients with large-artery atherosclerosis (CT/CC vs. TT — OR_adjusted 2.31, 95% CI 1.09–4.91; p=0.029), but not in patients with other types of IS.

Conclusion

This study suggested that PON1 rs662 presented a potential risk of IS, especially for males, and this association was more obvious for large-artery atherosclerosis.

Serum uric acid and risk of stroke: a dose-response meta-analysis

The relationship between serum uric acid and risk of stroke is still controversial. Therefore, we conducted a meta-analysis based on the cohort study to explore the relationship between serum uric acid and risk of stroke, and further illuminate whether there is a linear or non-linear relationship between them. We manually searched the database including Cochrane, PubMed, Embase, Web of Science, and selected cohort studies focusing on the relationship between serum uric acid and stroke risk. Random effect model was used for statistical analysis. Twenty-one cohort studies involving 818,098 participants were included. The pooled relative risk for the high-vs-low categories was 1.22 (95% CI: 1.15-1.30). In addition, there was a non-linear dose-response relationship between uric acid and stroke risk. Serum uric acid was in the range of 3-5 mg/dl, with the lowest risk of stroke. In conclusion, high serum uric acid level increases the risk of stroke, with a non-linear dose-response relationship.

Application of Genome-Wide Association Studies in Coronary Artery Disease

Coronary artery disease (CAD) is a complex disease caused by the combination of environmental and genetic factors. It is one of the leading causes of death and disability in the world. Much research has been focussed on CAD genetic mechanism. In recent years, genome-wide association study (GWAS) has developed rapidly around the world. Medical researchers around the world have successfully discovered a series of CAD genetic susceptibility genes or susceptible loci using medical research strategies, leading CAD research toward a new stage. This paper briefly summarizes the important progress made by GWAS for CAD in the world in recent years, and then analyzes the challenges faced by GWAS at this stage and the development trend of future research, to promote the transformation of genetic research results into clinical practice and provide guidance for further exploration of the genetic mechanism of CAD.

Haptoglobin genotype 2-2 associated with atherosclerosis in patients with ischemic stroke

AIM

Ischemic stroke (IS) is multifactorial disease and therefore different genes and proteins play a role in its development. Haptoglobin (Hp) removes free hemoglobin and protects from iron-induced oxidative damage, inflammatory response, atherosclerosis and cerebrovascular diseases. The aim of this study was to investigate Hp genetic variants in patients with carotid atherosclerotic lesions and IS.

MATERIAL AND METHODS

A total of 121 subjects with IS participated in the study, 81 male and 40 female.

RESULTS

Among 121 patients with IS, 79 had diffuse atherosclerotic plaques and stenosis. Hp genotype was statistically significantly associated with CDFI neck carotid artery stenosis findings (p = 0.006). Patients with Hp1-2 genotype had statistically significantly larger odds for atherosclerotic changes compared to those with Hp1-1 genotype, as well as those with Hp2-2 genotype.

CONCLUSION

This study has shown an association of the Hp2-2 genotype and atherosclerosis in patients with IS, indicating Hp2-2 genotype as a genetic biomarker for precision medicine and personalized healthcare.

The Role of the Endothelium in Premature Atherosclerosis: Molecular Mechanisms

Atherosclerotic disease is still one of the leading causes of mortality. Atherosclerosis is a complex progressive and systematic artery disease that involves the intima of the large and middle artery vessels. The inflammation has a key role in the pathophysiological process of the disease and the infiltration of the intima from monocytes, macrophages and T-lymphocytes combined with endothelial dysfunction and accumulated oxidized low-density lipoprotein (LDL) are the main findings of atherogenesis. The development of atherosclerosis involves multiple genetic and environmental factors. Although a large number of genes, genetic polymorphisms, and susceptible loci have been identified in chromosomal regions associated with atherosclerosis, it is the epigenetic process that regulates the chromosomal organization and genetic expression that plays a critical role in the pathogenesis of atherosclerosis. Despite the positive progress made in understanding the pathogenesis of atherosclerosis, the knowledge about the disease remains scarce.

Association between Lys198Asn polymorphism of endothelin-1 gene and ischemic stroke: A meta-analysis

BACKGROUND

Endothelin (ET)-1 is a potent vasoconstrictor peptide produced by endothelial cells and associated with vascular dysfunction and cardiovascular disease. Lys198Asn is a single-nucleotide polymorphism (SNP) of gene encoding ET-1 (EDN1). It is hypothesized that it might have a role in altering ET-1 and ultimately leading to vascular dysfunction and ischemic stroke. We therefore conducted a meta-analysis to investigate the association between Lys198Asn polymorphism of EDN1 gene and susceptibility of ischemic stroke.

METHODS

This meta-analysis was conducted according to the guidance of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. We searched PubMed, Google Scholar, Embase, Web of Science, J-STAGE, and China National Knowledge Infrastructure (CNKI) for relevant studies. The association between Lys198Asn polymorphism and ischemic stroke susceptibility was evaluated by calculating the pooled ORs and 95% CIs.

RESULTS

Our analysis included 1,291 cases and 2,513 controls. Meta-analysis established a significant association between Lys198Asn SNP of EDN1 gene and ischemic stroke when assuming either recessive model (OR: 1.30; 95% CI: 1.02-1.65; p = .03; I2  = 41%) or dominant model (OR: 1.48; 95% CI: 1.24-1.76; p < .001; I2  = 61%). There was no evidence of publication bias in either of the recessive model (Egger test: p = .23; Begg test: p = .85) or dominant model (Egger test: p = .79; Begg test: p = .85). A subgroup analysis based on subtypes of ischemic stroke showed that Lys198Asn SNP was only associated with large vessel infarction but not with lacunar infarction caused by small vessel disease. A subgroup analysis based on ethnicity revealed that the Lys198Asn polymorphism of the EDN1 gene was associated with ischemic stroke only in Caucasians.

CONCLUSIONS

The present meta-analysis suggests that Lys198Asn polymorphism of EDN1 gene is associated with an increased risk for ischemic stroke.

The Effect of AMBP SNPs, Their Haplotypes, and Gene-Environment Interactions on the Risk of Atherothrombotic Stroke Among the Chinese Population

Background/Objectives: Ischemic stroke (IS) is a severe and complex disorder with high morbidity and mortality rates and it has been associated with both environmental and genetic predisposing factors. The purpose of this study was to evaluate the association of the alpha-1-microglobulin/bikunin precursor (AMBP) gene polymorphisms with IS and any possible interactions between specific AMBP alleles and traditional risk factors among a Han Chinese cohort. Materials and Methods: We conducted a candidate gene study designed to characterize nine (9) single nucleotide polymorphisms (SNPs) of the AMBP gene among 195 patients with atherothrombotic stroke (ATS) (a major subtype of IS) and 184 nonstroke controls. Allelic and genotypic frequency differences were evaluated using a logistic regression model. False discovery rate (FDR) correction for multiple comparisons was used. The interactional analyses were performed using the multifactor dimensionality reduction test. Results: We found an association between the rs2567698 CC genotype (odds ratio [OR], 95% confidence interval [CI]: 2.176, 1.159-4.086) and the T allele (OR, 95% CI: 0.654, 0.446-0.960) with risk of ATS in men. However, these associations did not survive FDR correction. In haplotype analyses, the GCCCCCCCC haplotype had a higher frequency (OR, 95% CI: 2.191, 1.048-4.580) in ATS in the ≥45 years of age subgroup, whereas the GCCTCCCCC haplotype decreased the risk for ATS (OR, 95% CI: 0.543, 0.345-0.853) in men. In addition, we also found interactions for ATS risk between SNPs in the AMBP gene and modifiable risk factors for ATS, including: rs11788411 and hypertension in the overall population and women; rs2251680 and hypertension in subjects aged 45 years and older, as well as the interaction among hypertension and the rs2567698 and rs10817564 genotypes in men. Conclusion: Our results show a possible association between AMBP SNP haplotypes and gene-environment interactions with ATS susceptibility in a Han Chinese cohort.

Modifiable and non-modifiable risk factors in ischemic stroke: a meta-analysis

Background

Stroke is a heterogeneous, multifactorial disease regulated by modifiable and non-modifiable risk factors like total cholesterol, triglycerides, high density lipid-cholesterol (HDL-C), low density lipid-cholesterol (LDL-C) and glucose and non-modifiable factors like age. Evaluation of these risk factors for ischemic stroke may contribute to more effective prevention.

Methods

This meta-analysis investigated the data up to 2018 with respect to age, total cholesterol, triglycerides, high density lipid-cholesterol (HDL-C), low density lipid-cholesterol (LDL-C) and glucose levels in the Ischemic stroke patients and controls. Data from each eligible study was extracted such as year of publication, first author name, ethnicity/country, number of ischemic stroke patients and healthy controls and studies were subjected to heterogeneity analysis.

Results

Meta-analysis of the modifiable and non-modifiable risk factors like total cholesterol, HDL-C and LDL-C glucose, triglycerides levels and age were not having significantly associated with ischemic stroke (p>0.05). However meta-analysis of triglyceride yielded significant association ischemic stroke with overall 95% CI (−0.62- (−0.09) and P= 0.007 and glucose also showed significant association with ischemic stroke with 95% CI (-1.08- (−0.14), P=0.01. Studies were subjected to heterogeneity which revealed significant heterogeneity with (P<0.00) and I2>96%.

Conclusion

Meta-analysis revealed that levels of triglyceride and glucose are the predisposing factors for ischemic stroke in the Asian population.

Comparison of carotid plaque burden among healthy middle-aged men living in the US, Japan, and South Korea

BACKGROUND

Carotid plaque has emerged as a marker of coronary heart disease (CHD) risk. Comparison of carotid plaque burden between different race/ethnic groups may provide a relative estimate of their future CHD risk.

METHODS

We conducted a population-based study among apparently healthy middle-aged men aged 40-49 years (ERA JUMP study (n = 924)) and recruited 310 Whites in Pittsburgh, US, 313 Japanese in Otsu, Japan, and 301 Koreans in Ansan, South Korea. The number of carotid plaque and CHD risk factors was assessed using a standardized protocol across all centers. The burden of carotid plaque was compared between race/ethnic groups after adjustment for age and BMI, and after multivariable adjustment for other CHD risk factors using marginalized zero-inflated Poisson regression models. Cross-sectional associations of risk factors with plaque were examined.

RESULTS

Whites (22.8%) had more than four-fold higher prevalence (p < 0.01) of carotid plaque than Japanese men (4.8%) while the prevalence among Koreans was 10.6%. These differences remained significant after adjustment for age, BMI as well as other risk factors - incidence density ratio (95% confidence interval) for plaque was 0.13 (0.07, 0.24) for Japanese and 0.32 (0.18, 0.58) for Koreans as compared to Whites. Age, hypertension and diabetes were the only risk factors significantly associated with presence of carotid plaque in the overall population.

CONCLUSION

Whites have significantly higher carotid plaque burden than men in Japan and Korea. Lower carotid plaque burden among Japanese and Koreans is independent of traditional CVD risk factors.

Alterations in bone turnover markers in patients with noncardio-embolic ischemic stroke

Background

The major cause of ischemic stroke is unstable or thrombogenic atherosclerotic plaques. Vascular calcification, a process that appears crucial for plaque stability, shares common features with bone formation. Many bone turnover proteins exhibit metabolic properties, but the evidence is conflicting regarding their possible involvement in vascular disease. Antibodies against sclerostin and dickkopf-1 are currently being evaluated as potential therapy for treating bone disorders. It is important to carefully assess the cardiovascular and metabolic effects of these proteins. The aim of the present study was to explore serum levels of bone turnover markers in patients with acute noncardio-embolic ischemic stroke in comparison with healthy controls.

Methods

In a cross-sectional study, we compared 48 patients aged ≥75 years with noncardio-embolic ischemic stroke and 46 healthy controls. Serum levels of dickkopf-1, sclerostin, osteoprotegerin, osteopontin and osteocalcin were determined by Luminex technique.

Results

We found clearly increased serum levels of osteoprotegerin, sclerostin, dickkopf-1 and osteopontin in patients with stroke compared with healthy controls. No difference was seen in serum levels of osteocalcin between the two groups.

Conclusion

Our findings strengthen the hypothesis of bone turnover markers being involved in vascular disease. Whether these proteins can be used as candidate markers for increased stroke risk or prognostic biomarkers remains to be further elucidated.

The ANRIL Genetic Variants and Their Interactions with Environmental Risk Factors on Atherothrombotic Stroke in a Han Chinese Population

BACKGROUND

Ischemic stroke (IS) is considered to be a heterogeneous, multifactorial disease with a strong genetic background. This study aims to determine whether variants in the antisense noncoding RNA in the INK4 locus (ANRIL) gene are associated with IS in Han Chinese, as well as whether there is evidence of a gene-environment interactions.

MATERIALS AND METHODS

A case-controlled association study was conducted in which only patients with atherothrombotic stroke (ATS) were enrolled. Multifactor dimensionality reduction model was employed to screen the best interaction combinations among gene and environmental risk factors; RESULTS: A total of 405 subjects (200 cases and 205 controls) and 16 single nucleotide polymorphisms (SNPs) in ANRIL gene were included in this study. The 4 SNPs (rs1537378, rs2184061, rs7044859, and rs7865618) were found to be significantly related to ATS in Chinese Han nationality. In overall people or subjects aged 45 years or older, the GG genotype and G allele of rs1537378, the AA genotype and A allele of rs2184061 and rs7865618, and the AA genotype of rs7044859 increased the risk of ATS. In males, the GG genotype and G allele of rs1537378, the AA genotype and A allele of rs7865618, and the A allele of rs2184061 conferred a susceptibility to ATS. Additionally, the AAAGAGCAAAAAATAG haplotype exhibited an elevated risk of ATS, and a significant interaction was found in ATS susceptibility between ANRIL gene and dyslipidemia; CONCLUSIONS: The ANRIL gene was related to ATS susceptibility in a Han Chinese. Future studies should be performed with larger samples and among different ethnic populations.

Carotid Artery Atherosclerosis: A Review on Heritability and Genetics

Carotid atherosclerosis (CAS) is associated with increased cardiovascular risk, and therefore, assessing the genetic versus environmental background of CAS traits is of key importance. Carotid intima-media-thickness and plaque characteristics seem to be moderately heritable, with remarkable differences in both heritability and presence or severity of these traits among ethnicities. Although the considerable role of additive genetic effects is obvious, based on the results so far, there is an important emphasis on non-shared environmental factors as well. We aimed to collect and summarize the papers that investigate twin and family studies assessing the phenotypic variance attributable to genetic associations with CAS. Genes in relation to CAS markers were overviewed with a focus on genetic association studies and genome-wide association studies. Although the role of certain genes is confirmed by studies conducted on large populations and meta-analyses, many of them show conflicting results. A great focus should be on future studies elucidating the exact pathomechanism of these genes in CAS in order to imply them as novel therapeutic targets.

Genetic Risk Analysis of Coronary Artery Disease in a Population-based Study in Portugal, Using a Genetic Risk Score of 31 Variants

BACKGROUND

Genetic risk score can quantify individual's predisposition to coronary artery disease; however, its usefulness as an independent risk predictor remains inconclusive.

OBJECTIVE

To evaluate the incremental predictive value of a genetic risk score to traditional risk factors associated with coronary disease.

METHODS

Thirty-three genetic variants previously associated with coronary disease were analyzed in a case-control population with 2,888 individuals. A multiplicative genetic risk score was calculated and then divided into quartiles, with the 1st quartile as the reference class. Coronary risk was determined by logistic regression analysis. Then, a second logistic regression was performed with traditional risk factors and the last quartile of the genetic risk score. Based on this model, two ROC curves were constructed with and without the genetic score and compared by the Delong test. Statistical significance was considered when p values were less than 0.05.

RESULTS

The last quartile of the multiplicative genetic risk score revealed a significant increase in coronary artery disease risk (OR = 2.588; 95% CI: 2.090-3.204; p < 0.0001). The ROC curve based on traditional risk factors estimated an AUC of 0.72, which increased to 0.74 when the genetic risk score was added, revealing a better fit of the model (p < 0.0001).

CONCLUSIONS

In conclusion, a multilocus genetic risk score was associated with an increased risk for coronary disease in our population. The usual model of traditional risk factors can be improved by incorporating genetic data.

Stroke, Vascular Dementia, and Alzheimer's Disease: Molecular Links

Stroke is a brain disease that occurs when blood flow stops, resulting in reduced oxygen supply to neurons. Stroke occurs at any time and at any age, but increases after the age of 55. It is the second leading cause of death and the third leading cause of disability-adjusted, life-years. The pathophysiology of ischemic stroke is complex and recent molecular, cellular, and animal models and postmortem brain studies have revealed that multiple cellular changes have been implicated, including oxidative stress/mitochondrial dysfunction, inflammatory responses, micro RNA alterations, and marked changes in brain proteins. These cellular changes provide new information for developing therapeutic strategies for ischemic stroke treatment. Research also revealed that stroke increases with a number of modifiable factors and most strokes can be prevented and/or controlled through pharmacological or surgical interventions and lifestyle changes. Ischemic stroke is the major risk factor for vascular dementia and Alzheimer's disease. This review summarizes the latest research findings on stroke, including causal factors and molecular links between stroke and vascular disease/Alzheimer's disease.

Understanding AMD by analogy: systematic review of lipid-related common pathogenic mechanisms in AMD, AD, AS and GN

RATIONALE

Age-related macular degeneration (AMD) is one of the leading causes of blindness among the elderly. Due to its complex etiology, current treatments have been insufficient. Previous studies reveal three systems closely involved in AMD pathogenesis: lipid metabolism, oxidation and inflammation. These systems are also involved in Alzheimer's disease, atherosclerosis and glomerulonephritis. Understanding commonalities of these four diseases may provide insight into AMD etiology.

OBJECTIVES

To understand AMD pathogenesis by analogy and suggest ideas for future research, this study summarizes main commonalities in disease pathogenesis of AMD, Alzheimer's disease, atherosclerosis and glomerulonephritis.

METHODS

Articles were identified through PubMed, Ovid Medline and Google Scholar. We summarized the common findings and synthesized critical differences.

RESULTS

Oxidation, lipid deposition, complement activation, and macrophage recruitment are involved in all four diseases shown by genetic, molecular, animal and human studies. Shared genetic variations further strengthen their connection. Potential areas for future research are suggested throughout the review.

CONCLUSIONS

The four diseases share many steps of an overall framework of pathogenesis. Various oxidative sources cause oxidative stress. Oxidized lipids and related molecules accumulate and lead to complement activation, macrophage recruitment and pathology. Investigations that arise under this structure may aid us to better understand AMD pathology.

The Ubiquitin E3 Ligase TRAF6 Exacerbates Ischemic Stroke by Ubiquitinating and Activating Rac1

Stroke is one of the leading causes of morbidity and mortality worldwide. Inflammation, oxidative stress, apoptosis, and excitotoxicity contribute to neuronal death during ischemic stroke; however, the mechanisms underlying these complicated pathophysiological processes remain to be fully elucidated. Here, we found that the expression of tumor necrosis factor receptor-associated factor 6 (TRAF6) was markedly increased after cerebral ischemia/reperfusion (I/R) in mice. TRAF6 ablation in male mice decreased the infarct volume and neurological deficit scores and decreased proinflammatory signaling, oxidative stress, and neuronal death after cerebral I/R, whereas transgenic overexpression of TRAF6 in male mice exhibited the opposite effects. Mechanistically, we demonstrated that TRAF6 induced Rac1 activation and consequently promoted I/R injury by directly binding and ubiquitinating Rac1. Either functionally mutating the TRAF6 ubiquitination site on Rac1 or inactivating Rac1 with a specific inhibitor reversed the deleterious effects of TRAF6 overexpression during I/R injury. In conclusion, our study demonstrated that TRAF6 is a key promoter of ischemic signaling cascades and neuronal death after cerebral I/R injury. Therefore, the TRAF6/Rac1 pathway might be a promising target to attenuate cerebral I/R injury.SIGNIFICANCE STATEMENT Stroke is one of the most severe and devastating neurological diseases globally. The complicated pathophysiological processes restrict the translation of potential therapeutic targets into medicine. Further elucidating the molecular mechanisms underlying cerebral ischemia/reperfusion injury may open a new window for pharmacological interventions to promote recovery from stroke. Our study revealed that ischemia-induced tumor necrosis factor receptor-associated factor 6 (TRAF6) upregulation binds and ubiquitinates Rac1 directly, which promotes neuron death through neuroinflammation and neuro-oxidative signals. Therefore, precisely targeting the TRAF6-Rac1 axis may provide a novel therapeutic strategy for stroke recovery.

Association of FOXF2 gene polymorphisms with ischemic stroke in Chinese Han population

Recently, a novel locus at chromosome 6p25 (rs12204590, near FOXF2) associated with an increased risk of stroke in European populations was identified. However, whether polymorphisms in FOXF2 are also associated with the incidence of ischemic stroke in other populations remains unknown. In this case-control study, 803 Chinese Han patients with ischemic stroke and 803 matched control individuals were enrolled. Four tag SNPs and rs12204590 located in or near FOXF2 were selected, and the associations between genotypes/alleles and ischemic stroke were analyzed. In our study, we did not detect an association between the previously reported locus rs12204590 and ischemic stroke. By the genotype analysis, a novel SNP rs1711972, near FOXF2, was observed to be associated with an increased risk of ischemic stroke(CA genotype, adjusted OR = 1.35; 95% CI, 1.07 to 1.70), but not significantly after Bonferroni corrections for multiple tests. However, in the subgroup analysis, we discovered that rs1711972 was associated with an increased risk of large-artery atherosclerotic stroke in the additive model (P = 0.020; CA genotype, adjusted OR = 1.50; 95%CI, 1.09 to 2.07) and dominant model (P = 0.010; OR = 1.47; 95%CI, 1.09 to 1.99). Collectively, these results indicate that a novel SNP near FOXF2 may influence the risk of large-artery atherosclerotic stroke in Chinese Han population.

Impact of Tag Single Nucleotide Polymorphisms (SNPs) in CCL11 Gene on Risk of Subtypes of Ischemic Stroke in Xinjiang Han Populations

BACKGROUND CCL11 is an important inflammatory cytokine associated with inflammation-related diseases such as atherosclerosis and stroke. The aim of this study was to investigate the relationship between CCL11 gene polymorphism with subtypes of ischemic stroke in Xinjiang Han populations. MATERIAL AND METHODS The improved multiple ligase detection reaction (iMLDR) method was used to analyze the genotypes of 6 tag SNPs in the CCL11 gene (rs1129844, rs17809012, rs1860183, rs1860184, rs4795898, and rs4795895) in a case-control study of 406 lacunar stroke patients, 214 large-artery atherosclerotic (LAA) stroke patients, and 425 controls. RESULTS We found the GG genotype of rs4795895 was significantly associated with increased risk of lacunar stroke (adjusted OR=1.676, 95%CI=1.117-2.515), and the GA genotype of rs17809012 was associated with a significant increase in risk of LAA stroke (adjusted OR=1.337, 95%CI=1.127-1.585). Hypertension stratification analyses showed that the GA genotype of rs17809012 was significantly associated with LAA stroke in the hypertensive group (adjusted OR=1.274, 95%CI=1.015-1.601). In the non-hypertensive group, the GA genotype of rs17809012 was significantly associated with LAA stroke (adjusted OR=1.361, 95%CI=1.041-1.780). The GG genotype of rs4795895 (adjusted OR=1.147, 95%CI=1.115-4.134) and the TT genotype of rs1860184 were significantly associated with lacunar stroke (adjusted OR=2.440, 95%CI=1.550-3.840). CONCLUSIONS This study demonstrates that the CCL11 gene could play an important role in the pathogenesis of lacunar stroke and LAA stroke in the Han population of China.

Effect of APOE ε4 allele on survival and fertility in an adverse environment

Background

The apolipoprotein-ε4 allele (APOE-ε4) is strongly associated with detrimental outcomes in affluent populations including atherosclerotic disease, Alzheimer’s disease, and reduced lifespan. Despite these detrimental outcomes, population frequencies of APOE-ε4 are high. We hypothesize that the high frequency of APOE-ε4 was maintained because of beneficial effects during evolution when infectious pathogens were more prevalent and a major cause of mortality. We examined a rural Ghanaian population with a high pathogen exposure for selective advantages of APOE-ε4, to survival and or fertility.

Methods and findings

This rural Ghanaian population (n = 4311) has high levels of mortality from widespread infectious diseases which are the main cause of death. We examined whether APOE-ε4 was associated with survival (total follow-up time was 30,262 years) and fertility after stratifying by exposure to high or low pathogen levels. Households drawing water from open wells and rivers were classified as exposed to high pathogen levels while low pathogen exposure was classified as those drawing water from borehole wells. We found a non-significant, but positive survival benefit, i.e. the hazard ratio per APOE-ε4 allele was 0.80 (95% confidence interval: 0.69 to 1.05), adjusted for sex, tribe, and socioeconomic status. Among women aged 40 years and older (n = 842), APOE-ε4 was not associated with the lifetime number of children. However, APOE-ε4 was associated with higher fertility in women exposed to high pathogen levels. Compared with women not carrying an APOE-ε4 allele, those carrying one APOE-ε4 allele had on average one more child and those carrying two APOE-ε4 alleles had 3.5 more children (p = 0.018).

Conclusions

Contrary to affluent modern-day populations, APOE-ε4 did not carry a survival disadvantage in this rural Ghanaian population. Moreover, APOE-ε4 promotes fertility in highly infectious environments. Our findings suggest that APOE-ε4 may be considered as evolutionarily adaptive. Its adverse associations in affluent modern populations with later onset diseases of aging further characterize APOE-ε4 as an example of antagonistic pleiotropy.

Myeloperoxidase polymorphism and coronary artery disease risk: A meta-analysis

The myeloperoxidase (MPO) gene 463G/A and 129G/A polymorphisms have been reported to be associated with coronary artery disease (CAD), but the results remain inconclusive. This meta-analysis was designed to clarify these controversies.PubMed, EMBASE, and the Cochrane Library were used to retrieve the relevant literature up to March 2015 according to keywords. A total of 8 case-control studies, including 3491 cases and 7293 controls, were included in this meta-analysis. Summary odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were calculated.There was strong evidence of an association between the MPO 463G/A polymorphism and CAD. The data revealed that only the dominant model was associated with CAD (dominant model: OR = 0.872, 95% CI = 0.77-0.99). Regarding the 129G/A gene polymorphism, the pooled OR for the genotype AA + AG versus GG was 0.906 (95% CI = 0.74-1.10).This meta-analysis suggested an association between the MPO 463G/A polymorphism and the risk of CAD, but there is no significant association between the MPO 129G/A gene polymorphism and CAD risk.

The research on association of copy number variation in chromosome 9p21 region with atherothrombotic stroke in the Han Chinese population

BACKGROUND/PURPOSE

The copy number variants (CNVs) contain more genetic information compared with SNPs. The aim of this study was to elucidate whether the CNVs in Chromosome 9p21 region are associated with increased risk of Atherothrombotic stroke (ATS) in a Han Chinese population.

METHODS

A case-controlled association study was conducted in which only patients with ATS were enrolled. The CNVs were detected by the method of multiplex competitive amplification. The differences in distribution of CNVs between cases and controls were analyzed using univariate and multivariate logistic regression analysis. Subgroup analyses were also carried out to determine whether the effect of the CNVs was specific to age and gender among the subjects.

RESULTS

A total of 274 ATS patients and 282 health controls were included in the present study. 4 genes (ANRIL, CDKN2A, CDKN2B, and MTAP) including eight gene fragments in all were analyzed for CNV. The results showed that the copied number of most CNV in the 4 genes is two. There was no significant difference of CNV frequency between groups.

CONCLUSIONS

The obtained data suggested a negative association between CNV of the four genes and ATS. It is necessary to perform sequencing analyses across the entire 9p21 region for detecting rare or uncommon CNV.

Association of GWAS-Reported Variant rs11196288 near HABP2 with Ischemic Stroke in Chinese Han Population

A recent genome-wide association analysis identified a novel single nucleotide polymorphism locus on chromosome 10q25.3 (rs11196288, near HABP2) associated with the risk of early-onset ischemic stroke (IS) in European population, but not with late-onset IS. However, the role of this genome-wide association study (GWAS)-reported variant in ischemic stroke in Chinese Han population remained unknown. In our study, 389 adult ischemic stroke patients with an age of onset <60 years and 389 matched healthy controls were enrolled to investigate association of rs11196288 genotypes with early-onset ischemic stroke and its subtypes; the association was further examined in another independent population consisting of 349 ischemic stroke patients with an age of onset ≧60 years and 349 matched healthy individuals. Logistic regression analysis showed no significant association between rs11196288 and early-onset ischemic stroke (IS), large artery atherosclerotic (LAA) stroke, or small vessel disease (SVD) stroke (all P > 0.050). Nevertheless, in subgroup analysis of the older population, rs11196288 presented significant effect on late-onset SVD stroke susceptibility in the dominant model (GG/GA vs AA, OR 1.70; 95%CI 1.02 to 2.85; P = 0.042). The results indicated that the role of rs11196288 polymorphism in ischemic stroke susceptibility in Chinese Han population may be different from that in European. Larger studies with diverse populations are warranted to confirm and extend our findings.

Platelet glycoprotein gene Ia C807T, HPA-3, and Ibα VNTR polymorphisms are associated with increased ischemic stroke risk: Evidence from a comprehensive meta-analysis

Background/aims

Platelet glycoproteins play a crucial role in the initial stage of thrombus formation and may contribute to the pathophysiology of atherosclerosis. Polymorphisms in glycoprotein genes alter the function of the protein, possibly leading to increased risk of ischemic stroke. However, previous genetic association studies that examined the relationship between glycoprotein genes polymorphisms and ischemic stroke have yielded inconsistent results. This study aimed to evaluate the association between glycoprotein genes and ischemic stroke by the application of meta-analysis.

Methods

Relevant studies were identified by an extensive search through databases. The quality of included studies was assessed independently using the Newcastle–Ottawa Scale. Allele and genotype frequencies for each included study were extracted. The odds ratio (OR) with 95% confidence interval (95%CI) was calculated using a random-effects or fixed-effects model. Q statistic was used to evaluate homogeneity, and a meta-regression model was used to explore the study-level variables and to describe the heterogeneity in included studies. Egger’s test and funnel plot were used to assess publication bias.

Results

A total of 60 studies (9 polymorphisms) were included and identified in the current meta-analysis. The Newcastle–Ottawa Scale scores ranged from 7 to 9 except for two studies with Newcastle–Ottawa Scale scores of 6. The T allele or TT genotype of the glycoprotein Ia C807T polymorphism were associated with an increased susceptibility to ischemic stroke in combined population (807T allele: OR, 95%CI: 1.24, 1.03–1.50, p = 0.02) or Asian populations (807T allele: OR, 95%CI: 1.31, 1.10–1.54, p = 0.002 and 807TT genotype: OR, 95%CI: 1.53, 1.13–2.08, p = 0.006, respectively), and the Ser allele of HPA-3 was associated with increased risk of ischemic stroke in combined population or in Asians (OR, 95%CI: 1.21, 1.04–1.40, p = 0.01 or 1.54, 1.18–2.01, p = 0.001). Of note, the Ser/Ser genotype was more common in Asians (OR, 95%CI: 2.09, 1.40–3.13, p < 0.001). For glycoprotein Ibα variable number tandem repeat, only B allele showed a mild significant association with ischemic stroke risk in combined population or in Caucasians (OR, 95%CI: 2.17, 1.04–4.55, p = 0.04 or 1.79, 1.02–3.13, p = 0.04). There was no significant association between HPA-1, HPA-2, HPA-4, HPA-5, glycoprotein Ibα-5 T/C as well as Ia G873A polymorphisms and increased risk of ischemic stroke.

Conclusions

We found that glycoprotein Ia C807T T allele or the TT genotype, the Ser-allele of HPA-3 and B allele of glycoprotein Ibα variable number tandem repeat polymorphisms were associated with increased risk for ischemic stroke. Future studies with larger sample sizes will be necessary to confirm the results. In addition, analyses of ischemic stroke subtypes and gene–gene and gene–environment interactions are warranted.

Influence of the Cyclooxygenase-2 Gene -765G/C and -1195G/A Polymorphisms on Development of Ischemic Stroke

BACKGROUND

Many studies have investigated the association between the cyclooxygenase-2 (COX-2) gene polymorphism and ischemic stroke. However, results of these studies still remain controversial. To better explain the association between COX-2 polymorphisms (-765G/C and -1195G/A) and ischemic stroke risk, a meta-analysis was performed.

METHODS

Relevant studies were identified from 4 Chinese databases (Chinese Biological Medical Literature database, Chinese National Knowledge Infrastructure database, Chongqing VIP database, and Chinese WANFANG database), PUBMED and EMBASE prior to December 2015. The strength of association between COX-2 polymorphism and ischemic stroke was evaluated by the odds ratio (OR) with 95% confidence interval (CI). Inconsistency index (I(2)) and the Cochran's Q statistic were used to check heterogeneity. Publication bias was evaluated by funnel plots and Egger's regression test.

RESULTS

A total of 4086 ischemic stroke cases and 4747 controls were identified. Significant association between COX-2 -765G/C polymorphism and the risk of ischemic stroke was found in Brazilians and the African-Americans. The OR of (CC+GC versus GG) for the Brazilians and African-Americans were (6.328, 95% CI = 2.295-17.448) and (1.644, 95% CI = 1.060-2.551). In addition, the recessive model of the Brazilians gave an OR of 3.621 (95% CI: 1.519-8.630). Furthermore, the (GC versus GG) and the allele model of the African-Americans were (OR: 1.615, 95% CI = 1.015-2.572) and (OR: 1.422, 95% CI = 1.033-1.957). Significant association was also observed for COX-2 -1195G/A polymorphism in the subtypes of small vessel disease (SVD) of ischemic stroke.

CONCLUSIONS

Our study suggests that COX-2 -765G/C and -1195G/A polymorphisms may contribute to susceptibility of ischemic stroke, specifically in Brazilians and the African-Americans, and those of SVD.

Association of APOE (E2, E3 and E4) gene variants and lipid levels in ischemic stroke, its subtypes and hemorrhagic stroke in a South Indian population

In the present study we evaluated the association of APOE (E2/E3/E4) polymorphism with ischemic stroke (n=620), its subtypes and hemorrhagic stroke (n=250) in a South Indian population from Telangana. The genotypes were determined using PCR-RFLP while lipid levels were measured using commercially available kits. We found significant difference in the genotypic distribution between hemorrhagic stroke patients and controls for certain genetic models [E2/E2 vs. E2/E4; E3/E3 vs. E2/E3; E3/E3 vs. E2/E4; E4/E4 vs. E2/E3; E4/E4 vs.E2/E4 and E3 vs. E4]. However, no significant difference was observed in genotypic distribution between ischemic stroke patients and controls. On analysing the genotypic distribution between ischemic and hemorrhagic stroke patients, statistically significant difference was observed in specific genetic models [E2/E2 vs. E2/E4; E3/E3 vs. E2/E3; E3/E3 vs. E2/E4; E4/E4 vs. E2/E3 and E4/E4 vs. E2/E4]. In ischemic stroke subtypes analysing for alleles E3 vs. E2 and E3 vs. E4, we found significant association with intracranial large artery (p=0.01), cardioembolic stroke (p=0.001 and p=0.0004) and lacunar stroke (p=0.02). Analysing the association of various genotypes with different lipid levels significant association was observed for VLDL (P=0.000) and for triglyceride (P=0.000) levels with E2/E4 and E3/E4 genotypes in ischemic stroke but not in hemorrhagic stroke. In conclusion, our results suggest that APOE polymorphism does seem to play a role in hemorrhagic stroke and also in the development of specific subtypes of ischemic stroke. Further, in ischemic stroke VLDL and triglycerides levels were found to be significantly associated with E2/E4 and E3/E4 genotypes.

Impact of TLR5 rs5744174 on stroke risk, gene expression and on inflammatory cytokines, and lipid levels in stroke patients

Many studies reported that toll-like receptors (TLRs) played an important role in the process of ischemic stroke (IS). However, the impact of TLR5 rs5744174 on stroke risk, gene expression and on inflammatory cytokines, and lipid levels in ischemic stroke patients has not yet been reported and was therefore the subject of this study. In this case-control study, a total of 816 ischemic stroke patients and 816 healthy controls were genotyped using Sequenom MassArray technology. The mRNA expression of TLR5 was detected through quantitative real-time PCR among 52 ischemic stroke patients. The levels of IL-1b, IL-6, IL-8, and TNFα were measured by ELISA among 62 IS patients. Total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were determined among 816 IS patients using a Hitachi 7600 Automatic Biochemistry Analyzer. Our result showed TLR5 rs5744174 polymorphism was not associated with stroke risk, TLR5 mRNA expression and inflammatory cytokines of IS patients (P > 0.050), but was significantly associated with HDL-C (recessive model: β = - 0.14, 95 % CI: -0.24 to -0.03, P = 0.009). TLR5 rs5744174 polymorphism may have no impact on the stroke risk, gene expression and inflammatory cytokines, but may influence the HDL-C serum level of IS patients in Chinese Han population.

Impact of chromosome 12p13 variants on ischemic stroke risk

BACKGROUND

In 2009, a genome-wide association study (GWAS) identified two variants (rs12425791 and rs11833579) near NINJ2 gene that confer susceptibility to stroke in Caucasian populations. Recently, a number of studies have been conducted to replicate this finding in Asian populations. However, the results are conflicting. Thus, we performed a quantitative analysis to summarize the evidence regarding the association between these two polymorphisms and ischemic stroke risk.

METHODS

Pertinent studies were identified by searching PubMed and Embase through September 2014. Studies that reported odds ratio (OR) with 95% confidence interval (CI) for the association between these two polymorphisms and stroke risk were included.

RESULTS

Eight independent publications, with 8626 cases and 8046 controls for rs12425791 and 9142 cases and 8657 controls for rs11833579, were included. Overall, significantly increased ischemic stroke risk was associated with rs12425791 A allele when all studies were pooled into the meta-analysis (AA/GA vs. GG: OR = 1.08, 95% CI: 1.01-1.14). However, rs11833579 was not associated with increased stroke risk in any genetic model.

CONCLUSIONS

These findings indicate that rs12425791 G>A polymorphism may be a low-penetrance susceptibility marker of stroke in Asian populations and further studies are warranted to verify this association.

Association of C7673T polymorphism in apolipoprotein B gene with ischemic stroke in the Chinese population: a meta-analysis

BACKGROUND

Epidemiological studies have evaluated the association between the C7673T polymorphism in apolipoprotein B (apoB) gene and ischemic stroke (IS), but the results are still debatable even in the Chinese population. This meta-analysis was therefore designed to clarify these controversies.

METHODS

All of the relevant studies were identified from PubMed, Embase, Chinese National Knowledge Infrastructure database and Chinese Wanfang database up to 31 October 2014. Statistical analyses were conducted with Revman 5.2 and STATA 12.0 software. Odds ratio (OR) with 95% confidence interval (CI) values were applied to evaluate the strength of the association. A fixed or random effect model was selected for pooling data based on the heterogeneity test. Publication bias was assessed by Begg's test and Egger's test.

RESULTS

A significant association was found between the C7673T polymorphism in apoB gene and IS under the heterozygous genetic model (OR = 1.868, 95% CI = 1.160-3.007) and the allelic genetic model (OR = 1.742, 95% CI = 1.294-2.346), respectively. In the subgroup analysis by the geographic region, T allele could increase the risk of IS in northern Chinese (OR = 2.359, 95% CI: 1.425-3.907), but not in southern Chinese individuals (OR = 1.485, 95% CI: 0.778-2.832). Further stratification for source of controls showed that statistical significance was found among the population-based studies.

CONCLUSION

Our meta-analysis revealed that C7673T polymorphism in apoB gene was significantly associated with increased IS risk in the Chinese population.

Chromosome 12p13 variants contribute to large artery atherosclerotic stroke risk in a Chinese population

Recently, a genome-wide association study (GWAS) identified two common variants (rs12425791 and rs11833579) on Chromosome 12p13 that confer risk for stroke. The aim of this study was to evaluate whether these two variants are associated with risk of large artery atherosclerotic (LAA) stroke in a Chinese population. Rs12425791 and rs11833579 were genotyped using the improved multiple ligase detection reaction in 423 patients with LAA stroke and 423 healthy controls. We found a statistically significantly increased risk of LAA stroke associated with the rs12425791AA genotype (OR=2.28, 95% CI=1.15-4.51) and rs11833579 AA genotype (OR=1.92, 95% CI=1.16-3.15) compared with their GG genotype. When we evaluated these two polymorphisms together, we found that the combined genotypes with 3-4 variant alleles (rs12425791A and rs11833579A) were associated with an increased risk of LAA stroke (OR=2.06, 95% CI=1.26-3.36) compared to 0-2 variants. Moreover, genotype-phenotype correlation analysis showed that rs12425791AA and rs11833579AA carriers had significantly decreased NINJ2 mRNA expression levels in the Chinese population (P=0.003 for rs12425791 and P=0.005 for rs11833579). These results suggested that the rs12425791 and rs11833579 polymorphisms on Chromosome 12p13 may be associated with the risk of LAA stroke and might be used as candidate biomarkers for LAA stroke susceptibility.

Association Between TRAF6 Gene Polymorphisms and Susceptibility of Ischemic Stroke in Southern Chinese Han Population

The tumor necrosis factor receptor-associated factor 6 (TRAF6) gene encodes a protein that acts downstream of the Toll-like receptor (TLR) pathway. TLRs activate inflammatory cascades and mediate inflammatory injury after cerebral ischemia. However, the role of TFAR6 gene polymorphisms in ischemic stroke (IS) remains unknown. This study aims to investigate the associations of TRAF6 gene polymorphisms with susceptibility to IS and IS-related quantitative traits in Southern Chinese Han population. A total of 816 IS cases and 816 age- and gender-matched controls were included. Two variants of the TRAF6 gene (rs5030411 and rs5030416) were genotyped using the Sequenom MassARRAY iPLEX platform. Our study showed that rs5030416 was significantly associated with increased susceptibility to IS in the additive model [ORadj 1.25(1.04-1.51), P adj = 0.019, P Bc = 0.038] and dominant model [ORadj 1.23(1.04-1.60), P adj = 0.021, P Bc = 0.042] after adjusting by age and sex and applying a Bonferroni correction. No significant association was found between rs5030411 and IS susceptibility (all P > 0.05). The haplotype rs5030416 (allele C)-rs5030411 (allele C) was significantly associated with IS susceptibility (P adj = 0.015). Moreover, a significant association of rs5030411 with TC levels in IS patients under the additive model [β 0.16(0.01-0.30), P adj = 0.034] and recessive model [β 0.45(0.12-0.78), P adj = 0.007] was observed after adjustment by age and sex. This association remained statistically significant under the recessive model (P Bc = 0.042) after Bonferroni correction. Our results suggest that TRAF6 gene polymorphisms may be involved in the pathogenesis of IS.

Effect of the -148C/T, 448G/A, and -854G/A Polymorphisms of the β-Fibrinogen Gene on the Risk of Ischemic Stroke in Chinese Population

BACKGROUND

Several investigations have been performed to examine the influence of the β-fibrinogen (FGβ) gene polymorphisms on the risk of ischemic stroke, but the results of these studies are controversial. Our study aimed at investigating whether the FGβ gene (-148 C/T, 448 G/A, and -854 G/A) polymorphisms were associated with susceptibility to ischemic stroke by conducting meta-analysis.

METHODS

Relevant studies were identified from 4 Chinese databases, PUBMED and EMBASE before May 30, 2014. The strength of association was evaluated by the odds ratio with 95% confidence interval. Inconsistency index and the Cochran's Q statistic were used to check heterogeneity. Publication bias was tested using funnel plots and Egger's regression test.

RESULTS

Thirty-two independent studies with 4311 cases and 4124 controls were included. Significant association between -148 C/T polymorphism and the risk of ischemic stroke was found in overall analysis and middle-age, but not in young adults and elderly people. Similarly, association was also observed for -854 G/A polymorphism, especially in cerebral arterial main trunk infarction (MCI) and cerebral penetrating arterial infarction (PCI). However, no significance was found between 448 G/A polymorphism and ischemic stroke in Chinese people; likewise, no evidence of a significant association was observed when stratified according to the subtype of ischemic stroke (MCI and PCI).

CONCLUSIONS

These results suggest that -148 C/T and -854 G/A polymorphisms probably contribute to susceptibility of ischemic stroke.

PPARγ and IL-6 - 174G>C gene variants in Croatian patients with ischemic stroke

AIM

Etiology of ischemic stroke (IS) is multifactorial and includes interaction of genetic and environmental factors. Different genes, their polymorphisms, host susceptibility, and inflammation processes play a role in IS development. The aim of this study was to evaluate the effect of PPAR-γ and IL-6 gene variants on IS onset.

MATERIAL AND METHODS

A total of 301 subjects (144 males, 157 females) participated in the study, 114 patients with IS and 187 healthy controls.

RESULTS

Statistically significant predictors of IS were male gender (OR 7.13, 95% CI 2.92-17.39, p<0.001), hypertension (OR 7.82. 95% CI 2.53-24.19, p<0.001), lowered HDL cholesterol (OR 8.20, 95% CI 2.41-27.94, p=0.001), elevated C-reactive protein (OR 5.26, 95% CI 1.92-14.41) and IL-6 -174 GC (OR 2.44 95% CI 1.01-5.91, p=0.0048) genotype. Males, compared to females, had 7 times higher odds for stroke. IL6 -174G/C genotype increased the odds for IS for 2.4 times. PPARγ was not statistically significantly associated with stroke.

CONCLUSION

We can point to the IL-6 -174G>C polymorphisms as candidate gene marker and risk factor for the prediction of ischemic stroke.

Genetics of ischaemic stroke in young adults

Background

Stroke may be a clinical expression of several inherited disorders in humans. Recognition of the underlined genetic disorders causing stroke is important for a correct diagnosis, for genetic counselling and, even if rarely, for a correct therapeutic management. Moreover, the genetics of complex diseases such the stroke, in which multiple genes interact with environmental risk factors to increase risk, has been revolutionized by the Genome-Wide Association Study (GWAS) approach.

Scope of review

Here we review the single-gene causes of ischemic stroke, bringing the reader from the candidate gene method toward the exciting new horizons of genetic technology.

Major conclusions

The aetiological diagnosis of ischemic stroke in young adults is more complex than in the elderly. The identification of a genetic cause is important to provide appropriate counseling and to start a correct therapy, when available. The advent of GWAS technology, such as for other complex pathological conditions, has contributed enormously to the understanding of many of these genetic bases. For success large, well phenotyped case cohorts are required, and international collaborations are essential.

General significance

This review focuses on the main causes of genetically-based ischemic stroke in young adults, often classified as indeterminate, investigating also the recent findings of the GWAS, in order to improve diagnostic and therapeutic management.

•

The aetiological diagnosis of stroke in young adults needs a different and more complex diagnostic work up than in older adults.

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Stroke may be a clinical expression of several inherited disorders in humans.

•

The most common genetic causes of stroke are CADASIL, Fabry and mitochondrial diseases.

•

Recognition of the underlined genetic disorders causing stroke is important for the correct management of the patient.

Inflammatory markers and extent and progression of early atherosclerosis: Meta-analysis of individual-participant-data from 20 prospective studies of the PROG-IMT collaboration

BACKGROUND

Large-scale epidemiological evidence on the role of inflammation in early atherosclerosis, assessed by carotid ultrasound, is lacking. We aimed to quantify cross-sectional and longitudinal associations of inflammatory markers with common-carotid-artery intima-media thickness (CCA-IMT) in the general population.

METHODS

Information on high-sensitivity C-reactive protein, fibrinogen, leucocyte count and CCA-IMT was available in 20 prospective cohort studies of the PROG-IMT collaboration involving 49,097 participants free of pre-existing cardiovascular disease. Estimates of associations were calculated within each study and then combined using random-effects meta-analyses.

RESULTS

Mean baseline CCA-IMT amounted to 0.74 mm (SD = 0.18) and mean CCA-IMT progression over a mean of 3.9 years to 0.011 mm/year (SD = 0.039). Cross-sectional analyses showed positive linear associations between inflammatory markers and baseline CCA-IMT. After adjustment for traditional cardiovascular risk factors, mean differences in baseline CCA-IMT per one-SD higher inflammatory marker were: 0.0082 mm for high-sensitivity C-reactive protein (p < 0.001); 0.0072 mm for fibrinogen (p < 0.001); and 0.0025 mm for leucocyte count (p = 0.033). 'Inflammatory load', defined as the number of elevated inflammatory markers (i.e. in upper two quintiles), showed a positive linear association with baseline CCA-IMT (p < 0.001). Longitudinal associations of baseline inflammatory markers and changes therein with CCA-IMT progression were null or at most weak. Participants with the highest 'inflammatory load' had a greater CCA-IMT progression (p = 0.015).

CONCLUSION

Inflammation was independently associated with CCA-IMT cross-sectionally. The lack of clear associations with CCA-IMT progression may be explained by imprecision in its assessment within a limited time period. Our findings for 'inflammatory load' suggest important combined effects of the three inflammatory markers on early atherosclerosis.

TNFSF4 gene polymorphism rs3861950 but not rs3850641 is associated with the risk of cerebral infarction in a Chinese population

Tumor necrosis factor superfamily member 4 (TNFSF4) plays a key role in the process of atherosclerosis, a common risk factor for both myocardial and cerebral infarctions. Recent studies indicate that the single nucleotide polymorphism (SNP) rs3850641 in TNFSF4 is associated with higher risk of myocardial infarction, but little is known about the association between TNFSF4 variation and cerebral infarction (CI). A case-control study involving 385 CI patients and 385 age-matched, sex-matched non-CI controls was conducted in a Chinese population, only the most common subtype, atherosclerosis CI, was recruited. Two SNPs of TNFSF4, rs3850641 and rs3861950, were genotyped by the TaqMan SNP genotyping method, and verified partly by genomic DNA sequencing. The results revealed a significant allelic association between rs3861950 and CI (Odds ration = 1.733, 95 % confidence interval = 1.333-2.254, P = 0.000). Genotypic association analysis demonstrated that the CC genotype of rs3861950 confers susceptibility to CI (Odds ration = 2.896, 95 % confidence interval = 1.368-6.132), and it was associated with a significantly higher risk of ischemic stroke (Odds ration = 3.520, 95 % confidence interval = 1.546-8.015, P = 0.003) after adjusting for the other confirmed risk factors such as the history of hypertension, diabetes, CAD, smoking and alcohol drinking. While the odds ratio of the T allele to the C allele was 1.733 (95 % confidence interval: 1.333-2.254). However, there was no significant association between rs3850641 and CI (Odds ration = 1.288, 95 % confidence interval = 0.993-1.670, P = 0.056). TNFSF4 gene polymorphism rs3861950, but not rs3850641, is associated with the risk of atherosclerosis CI in a Chinese population.

Genetic polymorphism of β-fibrinogen gene-455G/A can contribute to the risk of ischemic stroke

Many studies have investigated the association between the β-fibrinogen gene-455G/A (FGβ-455G/A) polymorphism and the risk of ischemic stroke. However, these evidences were inadequate to provide stronger conclusions because most studies were generally small. To shed light on these inconclusive findings, we conducted a large sample size meta-analysis of studies relating to the FGβ-455G/A polymorphism and the risk of ischemic stroke. Odds ratios with a 95 % confidence interval were used to investigate the association between FGβ-455G/A polymorphism and ischemic stroke. Publication bias was tested by Egger's test and funnel plot. Inconsistency index and Cochran's Q statistic were used to check heterogeneity. Cumulative and recursive cumulative meta-analyses were performed to provide a framework for updating a genetic effect from all of the included studies. Twenty-six independent publications with 4,070 cases and 4,649 controls were included in this meta-analysis. Results showed that the β-fibrinogen-455G/A polymorphism was significantly associated with the risk of ischemic stroke. The FGβ-455G/A polymorphism was found to be a risk factor for ischemic stroke in Asians and adults, while association was not observed for Caucasians and juveniles based on the small size and it may be necessary to conduct larger studies on them to investigate the association in the future. The cumulative meta-analysis indicated a decline from 1998 to 2003, and the results remained stable during the period 2004-2012. The results indicate that FGβ-455G/A polymorphism may be a susceptible predictor of ischemic stroke. More studies are needed to elucidate the relationship further.

Hyperuricemia and risk of stroke: a systematic review and meta-analysis of prospective studies

INTRODUCTION

Hyperuricemia may be associated with an increased risk of stroke, but to date results from prospective studies have been inconsistent. This study aimed to evaluate the association between hyperuricemia and risk of stroke incidence and mortality by performing a meta-analysis.

MATERIALS AND METHODS

Studies were identified by searching multiple electronic databases through July 13, 2013, and by reviewing reference lists of obtained articles. Prospective studies reported a multivariate-adjusted estimate, represented as relative risk (RRs) with 95% confidence intervals (CIs) for the association between hyperuricemia and risk of stroke incidence and mortality were eligible. A random-effects model was used to compute the pooled risk estimate.

RESULTS

A total of fourteen articles including results from 15 prospective studies with 22,571 cases of stroke and 1,042,358 participants were included in the meta-analysis. Overall, presence of hyperuricemia was associated with a significantly greater risk of both stroke incidence (RR, 1.22; 95% CI, 1.02-1.46) and mortality (RR, 1.33; 95% CI, 1.24-1.43). In addition, the pooled estimate of multivariate RRs of stroke incidence and mortality were 1.08 (95% CI: 0.85-1.38); 1.26 (95% CI: 1.14-1.40) among men and 1.25 (95% CI: 1.04-1.46); 1.41 (95% CI: 1.31-1.52) among women respectively.

CONCLUSIONS

Results from this meta-analysis indicate that hyperuricemia may modestly increase the risks of both stroke incidence and mortality. Future studies should explore whether hyperuricemia is a modifiable risk factor for stroke.

Systems Biology of Human Atherosclerosis

Systems biology describes a holistic and integrative approach to understand physiology and pathology. The “omic” disciplines include genomics, transcriptomics, proteomics, and metabolic profiling (metabonomics and metabolomics). By adopting a stance, which is opposing (yet complimentary) to conventional research techniques, systems biology offers an overview by assessing the “net” biological effect imposed by a disease or nondisease state. There are a number of different organizational levels to be understood, from DNA to protein, metabolites, cells, organs and organisms, even beyond this to an organism’s context. Systems biology relies on the existence of “nodes” and “edges.” Nodes are the constituent part of the system being studied (eg, proteins in the proteome), while the edges are the way these constituents interact. In future, it will be increasingly important to collaborate, collating data from multiple studies to improve data sets, making them freely available and undertaking integrative analyses.