Evaluating the genetic component of ischemic stroke subtypes: a family history study

Integrating transcriptomic and polygenic risk scores to enhance predictive accuracy for ischemic stroke subtypes

Ischemic stroke (IS), characterized by complex etiological diversity, is a significant global health challenge. Recent advancements in genome-wide association studies (GWAS) and transcriptomic profiling offer promising avenues for enhanced risk prediction and understanding of disease mechanisms. GWAS summary statistics from the GIGASTROKE Consortium and genetic and phenotypic data from the UK Biobank (UKB) were used. Transcriptome-Wide Association Studies (TWAS) were conducted using FUSION to identify genes associated with IS and its subtypes across eight tissues. Colocalization analysis identified shared genetic variants influencing both gene expression and disease risk. Sum Transcriptome-Polygenic Risk Scores (STPRS) models were constructed by combining polygenic risk scores (PRS) and polygenic transcriptome risk scores (PTRS) using logistic regression. The predictive performance of STPRS was evaluated using the area under the curve (AUC). A Phenome-wide association study (PheWAS) explored associations between STPRS and various phenotypes. TWAS identified 34 susceptibility genes associated with IS and its subtypes. Colocalization analysis revealed 18 genes with a posterior probability (PP) H4 > 75% for joint expression quantitative trait loci (eQTL) and GWAS associations, highlighting their genetic relevance. The STPRS models demonstrated superior predictive accuracy compared to conventional PRS, showing significant associations with numerous UKB phenotypes, including atrial fibrillation and blood pressure. Integrating transcriptomic data with polygenic risk scores through STPRS enhances predictive accuracy for IS and its subtypes. This approach refines our understanding of the genetic and molecular landscape of stroke and paves the way for tailored preventive and therapeutic strategies.

Family history, waist circumference and risk of ischemic stroke: A prospective cohort study among Chinese adults

BACKGROUND AND AIMS

The associations between genetic factors and waist circumference (WC) with stroke risk have been evaluated in Western studies. However, evidence of this association has rarely been reported in the Chinese population. This study aimed to evaluate the association between WC and family history of stroke (FHS) with ischemic stroke (IS) risk among Chinese adults and to further explore the potential interaction of these associations.

METHODS AND RESULTS

The China Kadoorie Biobank (CKB) study recruited 35,508 participants aged 30-79 years from the Qingdao urban area during 2004-2008. A total of 33,355 participants were included in study. Cox regression analysis was used to estimate the multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI) for the independent and interactional associations between FHS and WC and IS risk. Participants with FHS had a 29% (HR = 1.29, 95% CI: 1.12-1.50) higher IS risk than those without FHS. Participants with excessive WC (85 cm for males and 80 cm for females) had a 78% (HR = 1.78, 95% CI: 1.51-2.10) higher IS risk than those with normal WC. The combined effect of FHS and excessive WC on IS was statistically significant (HR = 2.29, 95% CI: 1.84-2.86). The present study further found statistically significant multiplicative interactions of FHS and WC with IS risk (Pinteraction < 0.001).

CONCLUSION

The present study indicated that FHS and WC were significantly associated with an increased risk of IS. The association between FHS and IS was associated with excessive WC.

Association of MicroRNA Biogenesis Genes Polymorphisms with Risk of Large Artery Atherosclerosis Stroke

Convincing evidence has shown that microRNAs (miRNAs) are involved in the pathogenesis of stroke. This study aimed to examine whether miRNA biogenesis genes polymorphisms are associated with risk of large artery atherosclerosis (LAA) stroke. Three polymorphisms (DROSHA rs10719 T>C, RAN rs3803012 A>G, and PIWIL1 rs10773771 C>T) were screened by certain criteria. A total of 1,785 (710 cases and 1,075 controls) study subjects were included in this study. We found that rs10773771 CC genotype was associated with a decreased risk of LAA stroke (CC vs. TT/CT: OR 0.63, 95% CI 0.46-0.86, P = 3 × 10-3). In silico analysis suggested that rs10773771 can change the mRNA secondary structure of PIWIL1 and affect the binding of the miRNAs and regulatory motifs to the 3'-UTR of PIWIL1. Expression quantitative trait loci analysis showed that rs10773771 could change the expression of PIWIL1 in human skin (P = 1.534 × 10-10) and thyroid tissues (P = 4.869 × 10-6). These findings suggested that PIWIL1 rs10773771 may be associated with a decreased risk of LAA stroke.

Family History is Related to High Risk of Recurrent Events after Ischemic Stroke or Transient Ischemic Attack

OBJECTIVE

Prior data suggest paternal or sibling stroke was associated with increased risk of offspring stroke. Whether family history of cardiovascular disease (FHc) predicts risk of stroke recurrence remains unclear, we aim to determine this issue on patients with ischemic stroke (IS) or transient ischemic attack (TIA).

MATERIALS AND METHODS

This is a post hoc analysis based on the Third China National Stroke Registry III. IS/TIA patients with data of FHc status were included. FHc was defined as family history of coronary heart disease (CHD) or stroke among first-degree relatives (include parents, children, and siblings (same parents)). Cox proportional hazards regression models were performed to assess the association between FHc and recurrent events at 1 year follow-up.

RESULTS

Totally 14,208 patients with verified FHc status were included, 4,454 (31.3%) were female and the median (IQR) age was 62.0 (54.0, 70.0) years. Of these, 294 (2.1%), 726 (5.1%) and 1936 (13.6%) had family history of both CHD and stroke, family history of CHD, and family history of stroke only, respectively. Using multivariable Cox models adjusted for age, sex, and vascular risk factors, we found that patients with FHc experienced higher risk of stroke recurrence (HR=1.151, 95%CI=1.000-1.324) and combined vascular events (HR=1.186, 95%CI=1.036-1.358) at 1 year compared with those without FHc. In sensitivity analysis on patients who received primary secondary prevention treatment of antiplatelet and statins, the association persisted.

CONCLUSIONS

FHc is associated with increased risk of stroke recurrence even under primary secondary prevention treatment.

Etiology and risk factors of intracranial hemorrhage and ischemic stroke in young adults

BACKGROUND

Young stroke incidence has increased worldwide with lifestyle changes. Etiology and risk factors for both ischemic and hemorrhagic stroke in young Asians remain underexplored.

METHODS

We retrospectively reviewed consecutive acute stroke patients aged 16-45 years admitted to the Taipei Veterans General Hospital between 2009 and 2019 to analyze etiologic subtypes, risk factors, and serial modified Rankin Scale scores for 1 year and compare the age groups of 16-30 and 31-45 years.

RESULTS

Among 670 young Taiwanese patients (mean age at onset 37.5 ± 7.0 years; male 65.1%), there were 366 nontraumatic spontaneous hemorrhagic stroke (including 259 intracerebral hemorrhage [ICH] and 107 subarachnoid hemorrhage, SAH), 292 ischemic stroke and 12 cerebral venous thromboses. Notably, ICH was more prevalent in patients aged 16-30 than in those aged 31-45 (54.8% vs 36.8%). Specifically, structural vasculopathy (e.g., arteriovenous malformation, cavernoma) was the most common etiologic subtype in patients aged 16-30 (p < 0.001), whereas hypertensive ICH was the most common subtype in patients aged 31-45 (p < 0.001). On the other hand, the top ischemic subtype for both age groups was other determined diseases (e.g., arterial dissection, autoimmune diseases, moyamoya disease, etc.) rather than large artery atherosclerosis. Hyperlipidemia, diabetes, and cigarette smoking were more common risk factors for infarction than ICH. Familial stroke patients whose first- or second-degree relatives had a stroke by age 80 (n = 104, 15.5%) had more infarctions than those without a familial stroke history. In multivariate analyses, initial stroke severity, and infarction type were important predictors of favorable outcomes after 3 months. At the 1-year follow-up, patients with ICH and SAH had worse functional outcomes and survival rates than those with infarction.

CONCLUSION

An aggressive approach to elucidate the etiology of stroke is indicated because structural vasculopathy-induced ICH and other determined infarction are distinctively prevalent in young adults, particularly those aged 16-30.

Genetic basis of lacunar stroke: a pooled analysis of individual patient data and genome-wide association studies

BACKGROUND

The genetic basis of lacunar stroke is poorly understood, with a single locus on 16q24 identified to date. We sought to identify novel associations and provide mechanistic insights into the disease.

METHODS

We did a pooled analysis of data from newly recruited patients with an MRI-confirmed diagnosis of lacunar stroke and existing genome-wide association studies (GWAS). Patients were recruited from hospitals in the UK as part of the UK DNA Lacunar Stroke studies 1 and 2 and from collaborators within the International Stroke Genetics Consortium. Cases and controls were stratified by ancestry and two meta-analyses were done: a European ancestry analysis, and a transethnic analysis that included all ancestry groups. We also did a multi-trait analysis of GWAS, in a joint analysis with a study of cerebral white matter hyperintensities (an aetiologically related radiological trait), to find additional genetic associations. We did a transcriptome-wide association study (TWAS) to detect genes for which expression is associated with lacunar stroke; identified significantly enriched pathways using multi-marker analysis of genomic annotation; and evaluated cardiovascular risk factors causally associated with the disease using mendelian randomisation.

FINDINGS

Our meta-analysis comprised studies from Europe, the USA, and Australia, including 7338 cases and 254 798 controls, of which 2987 cases (matched with 29 540 controls) were confirmed using MRI. Five loci (ICA1L-WDR12-CARF-NBEAL1, ULK4, SPI1-SLC39A13-PSMC3-RAPSN, ZCCHC14, ZBTB14-EPB41L3) were found to be associated with lacunar stroke in the European or transethnic meta-analyses. A further seven loci (SLC25A44-PMF1-BGLAP, LOX-ZNF474-LOC100505841, FOXF2-FOXQ1, VTA1-GPR126, SH3PXD2A, HTRA1-ARMS2, COL4A2) were found to be associated in the multi-trait analysis with cerebral white matter hyperintensities (n=42 310). Two of the identified loci contain genes (COL4A2 and HTRA1) that are involved in monogenic lacunar stroke. The TWAS identified associations between the expression of six genes (SCL25A44, ULK4, CARF, FAM117B, ICA1L, NBEAL1) and lacunar stroke. Pathway analyses implicated disruption of the extracellular matrix, phosphatidylinositol 5 phosphate binding, and roundabout binding (false discovery rate <0·05). Mendelian randomisation analyses identified positive associations of elevated blood pressure, history of smoking, and type 2 diabetes with lacunar stroke.

INTERPRETATION

Lacunar stroke has a substantial heritable component, with 12 loci now identified that could represent future treatment targets. These loci provide insights into lacunar stroke pathogenesis, highlighting disruption of the vascular extracellular matrix (COL4A2, LOX, SH3PXD2A, GPR126, HTRA1), pericyte differentiation (FOXF2, GPR126), TGF-β signalling (HTRA1), and myelination (ULK4, GPR126) in disease risk.

FUNDING

British Heart Foundation.

Heterogeneity among women with stroke: health, demographic and healthcare utilization differentials

BACKGROUND

Although age specific stroke rates are higher in men, women have a higher lifetime risk and are more likely to die from a stroke. Despite this increased severity, most studies focus on male/female differences in stroke onset, patterns of care and stroke-related outcomes. Given that stroke presents differently in men and women, mixed sex studies fail to fully capture heterogeneity among women with stroke and the subsequent impact on their outcomes. This study examined the sociodemographic characteristics, factors related to stroke incidence and post-stroke functional status between young (< 60) and old (≥ 60) women with stroke.

METHODS

Using 5 years of data from the National Health Interview Survey (NHIS), a nationally representative sample of US adults, cohorts of young and old women with stroke were identified. A set of demographic/lifestyle, health services utilization and health status characteristics were used evaluate within gender heterogeneity in three ways. First, disparities in population characteristics were assessed using Chi-Square and t tests. Second, young and old women with stroke were matched with women without stroke in their respective cohorts to determine differences in factors related to stroke incidence. Finally, the determinants of post-stroke functional limitation for the two cohorts were determined.

RESULTS

Young women with stroke were more likely to be Black, smoke regularly and frequently consume alcohol than older women. Young women were also less likely to engage with their health provider regularly or receive preventative health screenings. Diabetes, high blood pressure, high cholesterol and high BMI were correlated with an increased relative likelihood of stroke among older women. In contrast, family size, smoking frequency, alcohol consumption and sleep were correlated with an increased prevalence of stroke among young women. Although factors correlated with stroke varied between young and old women, health status and receipt of healthcare were the most significant determinants of post-stroke functional status for both cohorts.

CONCLUSIONS

Health related characteristics were the primary correlates of stroke in older women, whereas post-stroke lifestyle and behaviors are the most significant correlates for younger stroke survivors. These findings suggest that while receipt of health services is essential for preventing stroke in both young and old women, providers should stress the importance of post-stoke lifestyle and behaviors to younger women at risk of stroke using approaches that may be different from older stroke women.

Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) represents a cluster of various vascular disorders with different pathological backgrounds. The advanced vasculature net of cerebral vessels, including small arteries, capillaries, arterioles and venules, is usually affected. Processes of oxidation underlie the pathology of CSVD, promoting the degenerative status of the epithelial layer. There are several classifications of cerebral small vessel diseases; some of them include diseases such as Binswanger’s disease, leukoaraiosis, cerebral microbleeds (CMBs) and lacunar strokes. This paper presents the characteristics of CSVD and the impact of the current knowledge of this topic on the diagnosis and treatment of patients.

Interactive Effects of a Combination of the HDAC3 and HDAC9 Genes with Diabetes Mellitus on the Risk of Ischemic Stroke

BACKGROUND AND AIM

 Previous studies indicated that the HDAC3 and HDAC9 genes play critical roles in atherosclerosis and ischemic stroke (IS). The purpose of this study was to investigate the association of combined single-nucleotide polymorphisms in the HDAC3 and HDAC9 genes with the susceptibility to IS.

METHODS

 A case-control study was conducted including 863 IS patients and 863 age- and gender-matched healthy participants. A polygenic score was developed to estimate the contribution of a combination of the HDAC3 and HDAC9 genes to the risk of IS. The interactive effects of traditional risk factors of stroke and the polygenic score on the risk of IS were explored. Additionally, the association between the polygenic score and the progression of atherosclerosis, a potential risk factor of IS, was examined in our healthy controls.

RESULTS

 Subjects with a higher polygenic score had an increased risk of IS (odds ratio: 1.83; 95% confidence interval: 1.38-2.43) after adjusting for covariates compared with individuals with a lower polygenic score. An interactive effect of diabetes mellitus and the polygenic score on the risk of IS was observed. A significant positive correlation between the polygenic score and a change in the plaque score (standardized β = 0.42, p = 0.0235) in healthy controls with diabetes mellitus was found.

CONCLUSION

 Our results suggested that the combination of the HDAC3 and HDAC9 genes with a history of diabetes mellitus could exacerbate the deterioration of atherosclerosis, thereby increasing the risk of IS. Further studies are warranted to explore our results in other populations.

Establishing molecular signatures of stroke focusing on omic approaches: a narrative review

Stroke or 'brain attack' is considered to be the major cause of mortality and morbidity worldwide after myocardial infraction. Inspite of the years of research and clinical practice, the pathogenesis of stroke still remains incompletely understood. Omics approaches not only enable the description of a huge number of molecular platforms but also have a potential to recognize new factors associated with various complex disorders including stroke. The most significant development among all other omics technologies over the recent years has been seen by genomics which is a powerful tool for exploring the genetic architecture of stroke. Genomics has decisively established itself in stroke research and by now wealth of data has been generated providing new insights into the physiology and pathophysiology of stroke. However, the efficacy of genomic data is restricted to risk prediction only. Omics approaches not only enable the description of a huge number of molecular platforms but also have a potential to recognize new factors associated with various complex disorders including stroke. The data generated by omics technologies enables clinicians to provide detailed insight into the makeup of stroke in individual patients, which will further help in developing diagnostic procedures to direct therapies. Present review has been compiled with an aim to understand the potential of integrated omics approach to help in characterization of mechanisms leading to stroke, to predict the patient risk of getting stroke by analyzing signature biomarkers and to develop targeted therapeutic strategies.

Polymorphism of IL6 receptor gene is associated with ischaemic stroke in patients with metabolic syndrome

The interleukin 6 receptor (IL6R) gene has been shown to locate in the chromosome 1q21 associated with metabolic syndrome (MetS), a condition related to the augmented risk of ischaemic stroke (IS), cardiovascular diseases and all-cause mortality. The aim of this study was to assess the relationship between IL6R gene polymorphisms and IS in patients with MetS in the Chinese Han population. We designed a case-control study enrolling 447 patients with MetS plus IS and 438 patients with MetS alone. Tag single nucleotide polymorphisms (SNPs) of the IL6R gene were determined by a fine-mapping strategy and genotyped using SNPscan technology. A logistic regression model was used to analzse the associations between the genetic variations in IL6R and the risk of IS in MetS patients. The linkage disequilibrium (LD) analysis was performed and four gamete rules were used to define the block. The haplotypes was reconstructed by the SNPstats software. Two SNPs were significantly related to the risk of IS in MetS patients after adjusting for potential confounders as follows: regarding rs12083537, the GG genotype and the GA genotype decreased the risk of IS in the MetS patients compared with the IS risk in the patients with the AA genotype (multivariate-adjusted, P = 0.005); and regarding rs8192284, the CC genotype and the AC genotype decreased the risk of IS compared with the IS risk in the patients with the AA genotype (multivariate-adjusted, P = 0.004). Strong LD was existed in block 2 and the haplotype analysis showed that compared with the ACCG haplotype, the ATCT haplotype (adjusted OR 1.700; 95% CI 1.246-2.319; P = 0.001) increased the risk of IS in the MetS patients. The analysis of the SNP-SNP interactions showed that rs8192284 was the most influential contributor to the risk of IS in the MetS patients. Our results indicate that rs12083537 and rs8192284 in the IL6R gene might be related to the risk of IS in MetS patients.

Association between a functional interleukin 6 receptor genetic variant and the risk and functional outcome of large artery atherosclerotic stroke

Purpose: To investigate whether the Asp358Ala of interleukin 6 receptor related to the risk and outcome of large artery atherosclerotic (LAA) stroke in Han Chinese.Materials and methods: A prospective cohort study was conducted on 768 patients with LAA stroke and 686 non-stroke controls. The genotypes of Asp358Ala polymorphism were determined using SNPscan technology. Associations between genotypes and the risk of LAA stroke were analyzed with logistic regression model.Results: CC genotype (P < 0.001) and AC genotype (P = 0.023) decreased the risk of LAA stroke compared with AA genotype. Multivariate logistic regression analysis revealed that CC genotype was significantly associated with the risk of LAA stroke (P = 0.002). In the subgroup analyses, polymorphisms of Asp358Ala were significantly associated with the risk of LAA stroke in additive model, dominant model and recessive model (P = 0.009, P = 0.017, P = 0.012, respectively) for male, but not for female. Further regression analysis showed that compared with participants with AA genotype and obesity, participants with CC genotype and non-obesity were less likely to suffer LAA stroke (P = 0.003). For male participants, these associations were still existed (additive model, P = 0.022). After 3-month follow-up, patients with C allele had good functional prognosis compared with patients with A allele (P = 0.009).Conclusion: The study demonstrated that the Asp358Ala polymorphism might be associated with susceptibility to the development and outcome of LAA stroke in Han Chines.

Integrative analysis of transcriptome-wide association study and gene expression profiling identifies candidate genes associated with stroke

Background

Stroke is a major public health burden worldwide. Although genetic variation is known to play a role in the pathogenesis of stroke, the specific pathogenic mechanisms are still unclear. Transcriptome-wide association studies (TWAS) is a powerful approach to prioritize candidate risk genes underlying complex traits. However, this approach has not been applied in stroke.

Methods

We conducted an integrative analysis of TWAS using data from the MEGASTROKE Consortium and gene expression profiling to identify candidate genes for the pathogenesis of stroke. Gene ontology (GO) enrichment analysis was also conducted to detect functional gene sets.

Results

The TWAS identified 515 transcriptome-wide significant tissue-specific genes, among which SLC25A44 (P = 5.46E−10) and LRCH1 (P = 1.54E−6) were significant by Bonferroni test for stroke. After validation with gene expression profiling, 19 unique genes were recognized. GO enrichment analysis identified eight significant GO functional gene sets, including regulation of cell shape (P = 0.0059), face morphogenesis (P = 0.0247), and positive regulation of ATPase activity (P = 0.0256).

Conclusions

Our study identified multiple stroke-associated genes and gene sets, and this analysis provided novel insights into the genetic mechanisms underlying stroke.

Pathophysiology of Lacunar Stroke: History's Mysteries and Modern Interpretations

Since the term "lacune" was adopted in the 1800s to describe infarctions from cerebral small vessels, their underlying pathophysiological basis remained obscure until the 1960s when Charles Miller Fisher performed several autopsy studies of stroke patients. He observed that the vessels displayed segmental arteriolar disorganization that was associated with vessel enlargement, hemorrhage, and fibrinoid deposition. He coined the term "lipohyalinosis" to describe the microvascular mechanism that engenders small subcortical infarcts in the absence of a compelling embolic source. Since Fisher's early descriptions of lipohyalinosis and lacunar stroke (LS), there have been many advancements in the understanding of this disease process. Herein, we review lipohyalinosis as it relates to modern concepts of cerebral small vessel disease (cSVD). We discuss clinical classifications of LS as well as radiographic definitions based on modern neuroimaging techniques. We provide a broad and comprehensive overview of LS pathophysiology both at the vessel and parenchymal levels. We also comment on the role of biomarkers, the possibility of systemic disease processes, and advancements in the genetics of cSVD. Lastly, we assess preclinical models that can aid in studying LS disease pathogenesis. Enhanced understanding of this highly prevalent disease will allow for the identification of novel therapeutic targets capable of mitigating disease sequelae.

A Genetic Variant of miR-34a Contributes to Susceptibility of Ischemic Stroke Among Chinese Population

miRNAs are small non-coding RNAs modulating gene expression, and variants in miRNA genes are involved in the pathogenesis of ischemic stroke (IS). However, the effect of miR-34a polymorphisms on IS susceptibility has rarely been reported. In the present study, we investigated the association between rs12128240, rs2666433, and rs6577555 of the miR-34a gene and IS susceptibility. Snapshot assay was used to detect miR-34a polymorphisms in 548 IS patients and 560 controls. Relative expression of miR-34a was measured by quantitative real-time PCR. We found that rs2666433 was associated with a significantly increased risk of IS (AA vs. GG: OR = 1.61, 95% CI = 1.05-2.52, P = 0.031; AA vs. GG+GA: OR = 1.58, 95% CI = 1.05-2.45, P = 0.026). For the IS subtypes, rs2666433 was associated with large artery atherosclerosis (AA vs. GG: OR = 2.09, 95% CI = 1.16-3.51, P = 0.007; AA vs. GG+GA: OR = 2.02, 95% CI = 1.15-3.33, P = 0.007; A vs. G: OR = 1.36, 95% CI = 1.07-1.81, P = 0.021). Additionally, the level of miR-34a was significantly up-regulated in IS patients compared to the controls (P < 0.001), and patients with rs2666433 AA genotype had a higher level of miR-34a than those with GG+GA genotypes (P < 0.001). Furthermore, increased level of homocysteine was observed in IS patients compared to the controls (P < 0.001), especially in patients carrying the rs2666433AA genotype compared to those carrying the rs2666433 GG+GA genotypes (P < 0.001). However, no significant association between rs12128240 or rs6577555 and IS was found. Collectively, our study found the association between miR-34a polymorphisms and the risk of IS among the Chinese population. The results may provide an explanation for etiology of IS and a potential biomarker or therapeutic target for IS. HIGHLIGHTS-MiR-34a rs2666433 polymorphism was associated with an increased risk of ischemic stroke.-The level of miR-34a was significantly up-regulated in ischemic stroke patients compared with controls, and patients with rs2666433 AA genotype had a higher level miR-34a than those with GG+GA genotypes.-Furthermore, increased level of homocysteine was showed in IS patients compared to controls, and in patients carrying the rs2666433AA compared to those carrying the rs2666433 GG+GA.

Identification of nine genes as novel susceptibility loci for early-onset ischemic stroke, intracerebral hemorrhage, or subarachnoid hemorrhage

Given that substantial genetic components have been shown in ischemic stroke, intracerebral hemorrhage (ICH), and subarachnoid hemorrhage (SAH), heritability may be higher in early-onset than late-onset individuals with these conditions. Although genome-wide association studies (GWASs) have identified various genes and loci significantly associated with ischemic stroke, ICH, or intracranial aneurysm mainly in European ancestry populations, genetic variants that contribute to susceptibility to these disorders remain to be identified definitively. We performed exome-wide association studies (EWASs) to identify genetic variants that confer susceptibility to ischemic stroke, ICH, or SAH in early-onset subjects with these conditions. A total of 6,649 individuals aged ≤65 years were examined. For the EWAS of ischemic or hemorrhagic stroke, 6,224 individuals (450 subjects with ischemic stroke, 5,774 controls) or 6,179 individuals (261 subjects with ICH, 176 subjects with SAH, 5,742 controls), respectively, were examined. EWASs were performed with the use of Illumina Human Exome-12 v1.2 DNA Analysis BeadChip or Infinium Exome-24 v1.0 BeadChip. To compensate for multiple comparisons of allele frequencies with ischemic stroke, ICH, or SAH, we applied a false discovery rate (FDR) of <0.05 for statistical significance of association. The association of allele frequencies of 31,245 single nucleotide polymorphisms (SNPs) that passed quality control to ischemic stroke was examined with Fisher's exact test, and 31 SNPs were significantly (FDR <0.05) associated with ischemic stroke. The association of allele frequencies of 31,253 or 30,970 SNPs to ICH or SAH, respectively, was examined with Fisher's exact test, and six or two SNPs were significantly associated with ICH or SAH, respectively. Multivariable logistic regression analysis with adjustment for age, sex, and the prevalence of hypertension and diabetes mellitus revealed that 12 SNPs were significantly [P<0.0004 (0.05/124)] related to ischemic stroke. Similar analysis with adjustment for age, sex, and the prevalence of hypertension revealed that six or two SNPs were significantly [P<0.0016 (0.05/32)] related to ICH or SAH, respectively. After examination of linkage disequilibrium of identified SNPs and results of previous GWASs, we identified HHIPL2, CTNNA3, LOC643770, UTP20, and TRIB3 as susceptibility loci for ischemic stroke, DNTTIP2 and FAM205A as susceptibility loci for ICH, and FAM160A1 and OR52E4 as such loci for SAH. Therefore, to the best of our knowledge, we have newly identified nine genes that confer susceptibility to early-onset ischemic stroke, ICH, or SAH. Determination of genotypes for the SNPs in these genes may prove informative for assessment of the genetic risk for ischemic stroke, ICH, or SAH in Japanese.

[Role of and genes polymorphisms in the pathogenesis of stroke of the Erzya population in the Republic of Mordovia]

AIM

To determine the frequency of GPIIIa and eNOS genes polymorphisms in patients with ischemic stroke in the Erzya population in the Republic of Mordovia.

MATERIAL AND METHODS

An open, prospective, randomized study included 4 groups: 1) Erzya with ischemic stroke (main group, n=65), 2) Russians with ischemic stroke (comparison group, n=60), 3) Erzya healthy volunteers (control-1, n=63), 4) Russian healthy volunteers (control-2, n=61). T1565C polymorphism of GPIIIa gene (rs5918) and G894T polymorphism of eNOS gene (rs1799983) were determined by real-time PCR.

RESULTS AND CONCLUSION

In the population of healthy Erzya, the accumulation of mutant alleles of the GPIIIa gene was observed with less frequency than in healthy Russians, however, in the absence of differences in the frequency of homozygous carriage of both mutant and normal alleles, in the Erzya, the accumulation of the mutant allele in heterozygous genotypes prevailed. In patients with stroke, the probability of detecting the allele C of the GPIIIa gene in the Erzya was significantly higher than in the Russians, as was the likelihood of heterozygous carriage of the C/T genotype. No differences between eNOS allele frequencies were found between the groups of healthy Erzya and Russian volunteers. The higher frequency of the mutant allele T was found in Russian patients with stroke while the heterozygous carriage of the G/T genotype, which had an unfavorable prognostic value, predominated in the Erzya.

Associations between thromboxane A synthase 1 gene polymorphisms and the risk of ischemic stroke in a Chinese Han population

Thromboxane A synthase 1 (TBXAS1) catalyses the synthesis of thromboxane A2 (TXA2), which plays an important role in the pathogenesis of ischemic stroke. Thus, the TBXAS1 gene was investigated as a candidate gene involved in the formation of atherosclerosis. This case-control study collected peripheral blood specimens and clinical data of 370 ischemic stroke patients and 340 healthy controls in the Northern Chinese Han population from October 2010 to May 2011. Two TBXAS1 single-nucleotide polymorphisms, rs2267682 and rs10487667, were analyzed using a SNaPshot Multiplex sequencing assay to explore the relationships between the single-nucleotide polymorphisms in TBXAS1 and ischemic stroke. The TT genotype frequency and T allele frequency of rs2267682 in the patients with ischemic stroke were significantly higher than those in the controls (P < 0.01 and P = 0.02). Furthermore, compared with the GG + GT genotype, the TT rs2267682 genotype was associated with increased risk of ischemic stroke (odds ratio (OR) = 1.80, 95% confidence interval (CI): 1.16–2.79, P < 0.01). Multivariate logistic analysis with adjustments for confounding factors revealed that rs2267682 was still associated with ischemic stroke (OR = 1.94, 95% CI : 1.13–3.33, P = 0.02). The frequency of the T-G haplotype in the patients was significantly higher than that in the controls according haplotype analysis (OR = 1.49, 95% CI: 1.10–2.00, P < 0.01). These data reveal that the rs2267682 TBXAS1 polymorphism is associated with ischemic stroke. The TT genotype of TBXAS1 and T allele of rs2267682 increase susceptibility to ischemic stroke in this Northern Chinese Han population. The protocol has been registered with the Chinese Clinical Trial Registry (registration number: ChiCTR-COC-17013559).

Apolipoprotein E polymorphisms are associated with ischemic stroke susceptibility in a Northwest China Han population

Ischemic stroke (IS), the leading neurology cause of death and disability worldwide, is influenced by gene polymorphisms. To explore the association between IS and Apolipoprotein E (APOE) gene polymorphisms, a case–control study containing 513 IS patients and 514 controls without IS was conducted in a Northwest China Han population. MassARRAY iPLEX system was applied to determine the APOE polymorphisms according to the alleles of two single nucleotide polymorphisms (SNPs) of APOE, rs429358, and rs7412. The results showed that rs429358 and rs7412 were in Hardy–Weinberg equilibrium (HWE) in both cases and controls groups. APOE ε4 allele, ε4/ε4 genotype, and ε4-containing genotypes were associated with IS. According to the results of Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification system, APOE ε2 allele, ε4 allele, and ε4/ε4 genotype were associated with large artery atherosclerosis IS subtypes. In addition, the results also indicated that the ε4 allele related to undetermined IS and ε4/ε4 genotype was related to small vessel disease IS. Compared with subjects with non-ε4-containing genotypes, the total cholesterol (TC) and low-density lipoprotein (LDL) level in blood and the proportion of cardiopath history were higher in all subjects with ε4-containing genotypes. Besides, the triacylglycerides (TG) level in blood was higher in controls with ε4-containing genotypes. In conclusion, in a Northwest China Han population, APOE ε4 allele was associated with blood lipid level. The TC and LDL levels were the independent risk factors for IS. APOE was a risk gene for IS, but not independent, especially for large artery atherosclerosis IS.

Canadian stroke best practice recommendations: Secondary prevention of stroke, sixth edition practice guidelines, update 2017

The 2017 update of The Canadian Stroke Best Practice Recommendations for the Secondary Prevention of Stroke is a collection of current evidence-based recommendations intended for use by clinicians across a wide range of settings. The goal is to provide guidance for the prevention of ischemic stroke recurrence through the identification and management of modifiable vascular risk factors. Recommendations include those related to diagnostic testing, diet and lifestyle, smoking, hypertension, hyperlipidemia, diabetes, antiplatelet and anticoagulant therapies, carotid artery disease, atrial fibrillation, and other cardiac conditions. Notable changes in this sixth edition include the development of core elements for delivering secondary stroke prevention services, the addition of a section on cervical artery dissection, new recommendations regarding the management of patent foramen ovale, and the removal of the recommendations on management of sleep apnea. The Canadian Stroke Best Practice Recommendations include a range of supporting materials such as implementation resources to facilitate the adoption of evidence to practice, and related performance measures to enable monitoring of uptake and effectiveness of the recommendations. The guidelines further emphasize the need for a systems approach to stroke care, involving an interprofessional team, with access to specialists regardless of patient location, and the need to overcome geographic barriers to ensure equity in access within a universal health care system.

A genome-wide association study links small-vessel ischemic stroke to autophagy

Genome-wide association studies (GWAS) can serve as strong evidence in correlating biological pathways with human diseases. Although ischemic stroke has been found to be associated with many biological pathways, the genetic mechanism of ischemic stroke is still unclear. Here, we performed GWAS for a major subtype of stroke-small-vessel occlusion (SVO)-to identify potential genetic factors contributing to ischemic stroke. GWAS were conducted on 342 individuals with SVO stroke and 1,731 controls from a Han Chinese population residing in Taiwan. The study was replicated in an independent Han Chinese population comprising an additional 188 SVO stroke cases and 1,265 controls. Three SNPs (rs2594966, rs2594973, rs4684776) clustered at 3p25.3 in ATG7 (encoding Autophagy Related 7), with P values between 2.52 × 10-6 and 3.59 × 10-6, were identified. Imputation analysis also supported the association between ATG7 and SVO stroke. To our knowledge, this is the first GWAS to link stroke and autophagy. ATG7, which has been implicated in autophagy, could provide novel insights into the genetic basis of ischemic stroke.

Neonatal Arterial Ischemic Stroke: Risk Related to Family History, Maternal Diseases, and Genetic Thrombophilia

The objective of this study was to evaluate the heritability of neonatal arterial ischemic stroke (NAIS) in relation to family history of thromboembolic event, maternal diseases, and thrombophilia in both parents ( F5G1691A, F2G20210A, and MTHFRC677 T mutations). Forty-two consecutive infants ≥36 weeks of gestation <28 days of life with acute symptomatic NAIS and their parents, as well as 129 controls, were prospectively recruited. Information on maternal data (age, body mass index, oral contraception, migraine, epilepsy, hypertension, and immune disease) and a 3-generation pedigree regarding myocardial infarction, pulmonary embolism, cerebrovascular event, and deep vein thrombosis were obtained. Thrombophilia and maternal diseases did not differ between cases and controls, except for the use of oral contraceptives (more frequent in mothers of controls). No differences were found regarding each studied antecedent of thromboembolic event in the families. The NAIS group showed a higher presence of positive family history among second-degree maternal relatives than did the control infants (odds ratio 4.10; 95% confidence interval 1.29-12.99). Our study does not support the hypothesis that common genetic thrombophilia or familial predisposition to thromboembolic events is associated with the occurrence of idiopathic NAIS.

Genetic variation at 16q24.2 is associated with small vessel stroke

Objective

Genome‐wide association studies (GWAS) have been successful at identifying associations with stroke and stroke subtypes, but have not yet identified any associations solely with small vessel stroke (SVS). SVS comprises one quarter of all ischemic stroke and is a major manifestation of cerebral small vessel disease, the primary cause of vascular cognitive impairment. Studies across neurological traits have shown that younger‐onset cases have an increased genetic burden. We leveraged this increased genetic burden by performing an age‐at‐onset informed GWAS meta‐analysis, including a large younger‐onset SVS population, to identify novel associations with stroke.

Methods

We used a three‐stage age‐at‐onset informed GWAS to identify novel genetic variants associated with stroke. On identifying a novel locus associated with SVS, we assessed its influence on other small vessel disease phenotypes, as well as on messenger RNA (mRNA) expression of nearby genes, and on DNA methylation of nearby CpG sites in whole blood and in the fetal brain.

Results

We identified an association with SVS in 4,203 cases and 50,728 controls on chromosome 16q24.2 (odds ratio [OR; 95% confidence interval {CI}] = 1.16 [1.10–1.22]; p = 3.2 × 10⁻⁹). The lead single‐nucleotide polymorphism (rs12445022) was also associated with cerebral white matter hyperintensities (OR [95% CI] = 1.10 [1.05–1.16]; p = 5.3 × 10⁻⁵; N = 3,670), but not intracerebral hemorrhage (OR [95% CI] = 0.97 [0.84–1.12]; p = 0.71; 1,545 cases, 1,481 controls). rs12445022 is associated with mRNA expression of ZCCHC14 in arterial tissues (p = 9.4 × 10⁻⁷) and DNA methylation at probe cg16596957 in whole blood (p = 5.3 × 10⁻⁶).

Interpretation

16q24.2 is associated with SVS. Associations of the locus with expression of ZCCHC14 and DNA methylation suggest the locus acts through changes to regulatory elements. Ann Neurol 2017;81:383–394

Risk Factors and Etiology of Young Ischemic Stroke Patients in Estonia

Objectives

Reports on young patients with ischemic stroke from Eastern Europe have been scarce. This study aimed to assess risk factors and etiology of first-ever and recurrent stroke among young Estonian patients.

Methods

We performed a retrospective study of consecutive ischemic stroke patients aged 18–54 years who were treated in our two hospitals from 2003 to 2012.

Results

We identified 741 patients with first-ever stroke and 96 patients with recurrent stroke. Among first-time patients, men predominated in all age groups. The prevalence of well-documented risk factors in first-time stroke patients was 83% and in the recurrent group 91%. The most frequent risk factors were hypertension (53%), dyslipidemia (46%), and smoking (35%). Recurrent stroke patients had fewer less well-documented risk factors compared to first-time stroke patients (19.8 versus 30.0%, P = 0.036). Atrial fibrillation was the most common cause of cardioembolic strokes (48%) and large-artery atherosclerosis (LAA) was the cause in 8% among those aged <35 years. Compared to first-time strokes, recurrent ones were more frequently caused by LAA (14.3 versus 24.0%, P = 0.01) and less often by other definite etiology (8.5 versus 1.0%, P = 0.01).

Conclusions

The prevalence of vascular risk factors among Estonian young stroke patients is high. Premature atherosclerosis is a cause in a substantial part of very young stroke patients.

HIV infection, hypercoagulability and ischaemic stroke in adults at the University Teaching Hospital in Zambia: a case control study

BACKGROUND

In Zambia, 14.2% of adults have HIV/AIDS. There has been a substantial and significant increase in patients hospitalized for ischaemic stroke with co-existing HIV infection. However, little is known about the mechanism of stroke in these HIV + ve patients let alone studied in our region. The aim of this pilot study was to explore the association of hypercoagulability state in HIV + ve patients with ischaemic stroke. This was achieved by comparing hypercoagulability state markers between HIV + ve ischaemic stroke patients with HIV-ve and HIV + ve patients with and without ischaemic stroke respectively.

METHODS

A matched case control study in which a total of 52 HIV + ve patients with ischaemic stroke were prospectively compared with control groups for the presence of protein S, protein C deficiencies and hyperhomocysteinaemia. The control groups comprised an equal number of consecutively matched for age and sex HIV-ve and HIV + ve patients with and without ischaemic stroke respectively. Data was analysed in contingency tables using Paired t- test, Chi square and conditional logistic regression.

RESULTS

Ischaemic stroke of undetermined aetiology occurred more frequently in HIV + ve compared to HIV-ve patients (p < 0.001). In addition, protein S deficiency and Hyperhomocysteinaemia were more prominent in HIV + ve than HIV-ve ischaemic stroke patients (P = 0.011). There was no difference in the presence of hyperhomocysteinaemia or protein S deficiency in HIV + ve patients with or without ischaemic stroke. Protein C deficiency was not noted to be significantly different between the cases and the two control arms.

CONCLUSION

Protein S deficiency and hyperhomocysteinaemia were associated with HIV infection, but not stroke in our study population. However, this is an area that requires extensive research and one that we cannot afford to ignore as it is an important bridge to all cardiovascular and cerebrovascular diseases.

New insights into mechanisms of small vessel disease stroke from genetics

Cerebral small vessel disease (SVD) is a common cause of lacunar strokes, vascular cognitive impairment (VCI) and vascular dementia. SVD is thought to result in reduced cerebral blood flow, impaired cerebral autoregulation and increased blood–brain barrier (BBB) permeability. However, the molecular mechanisms underlying SVD are incompletely understood. Recent studies in monogenic forms of SVD, such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), and ‘sporadic’ SVD have shed light on possible disease mechanisms in SVD. Proteomic and biochemical studies in post-mortem monogenic SVD patients, as well as in animal models of monogenic disease have suggested that disease pathways are shared between different types of monogenic disease, often involving the impairment of extracellular matrix (ECM) function. In addition, genetic studies in ‘sporadic’ SVD have also shown that the disease is highly heritable, particularly among young-onset stroke patients, and that common variants in monogenic disease genes may contribute to disease processes in some SVD subtypes. Genetic studies in sporadic lacunar stroke patients have also suggested distinct genetic mechanisms between subtypes of SVD. Genome-wide association studies (GWAS) have also shed light on other potential disease mechanisms that may be shared with other diseases involving the white matter, or with pathways implicated in monogenic disease. This review brings together recent data from studies in monogenic SVD and genetic studies in ‘sporadic’ SVD. It aims to show how these provide new insights into the pathogenesis of SVD, and highlights the possible convergence of disease mechanisms in monogenic and sporadic SVD.

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.

Polymorphism of the XRCC1 Gene Is Associated with Susceptibility and Short-Term Recovery of Ischemic Stroke

Background: Base excision repair (BER) is the primary DNA repair system with the ability to fix base lesions caused by oxidative damage. Genetic variants influencing the BER pathway may affect the susceptibility and the outcomes of ischemic stroke. Here, we examined how single nucleotide polymorphisms (SNPs) associated with BER impact susceptibility and short-term recovery of ischemic stroke. Methods: We selected 320 ischemic stroke patients and 303 controls. Then we genotyped SNPs of NEIL1 rs4462560, NEIL3 rs12645561 and XRCC1 rs25487 in both groups. Results: Polymorphism in XRCC1 rs25487 was significantly associated with reduced ischemic stroke (IS) risk (dominant model: OR = 0.53, 95% CI = 0.36-0.79, p = 0.002), a milder initial stroke (dominant model: OR = 0.57, 95% CI = 0.33-0.98, p = 0.043), and also a better short-term recovery (dominant model: OR = 0.57, 95% CI = 0.35-0.92, p = 0.022). No association was observed in the other two SNPs. Conclusions: Our study suggests that the genetic variant of XRCC1 rs25487 may contribute to the etiology of ischemic stroke.

A Family History of Stroke Is Associated with Increased Intima-Media Thickness in Young Ischemic Stroke - The Norwegian Stroke in the Young Study (NOR-SYS)

Background and Purpose

Positive family history (FH+) of cardiovascular disease (CVD) is a risk factor for own CVD. We aimed to analyze the effect of different types of FH (stroke, coronary heart disease (CHD), peripheral artery disease (PAD) on carotid intima-media thickness (cIMT) in young and middle-aged ischemic stroke patients.

Methods

First-degree FH of CVD was assessed in ischemic stroke patients ≤ 60y using a standardized interview. Carotid ultrasound was performed and far wall cIMT in three carotid artery segments was registered, representing the common carotid (CCA-IMT), carotid bifurcation (BIF-IMT) and the internal carotid artery (ICA-IMT). Measurements were compared between FH+ and FH negative groups and stepwise backward regression analyses were performed to identify factors associated with increased cIMT.

Results

During the study period 382 patients were enrolled, of which 262 (68%) were males and 233 (61%) reported FH of CVD. Regression analyses adjusting for risk factors revealed age as the most important predictor of cIMT in all segments. The association between FH+ and cIMT was modified by age (p = 0.014) and was significant only regarding ICA-IMT. FH+ was associated with increased ICA-IMT in patients aged < 45y (p = 0.001), but not in patients ≥ 45y (p = 0.083). The association with ICA-IMT was present for a FH of stroke (p = 0.034), but not a FH+ of CHD or PAD.

Conclusions

FH of stroke is associated with higher ICA-IMT in young ischemic stroke patients. Subtyping of cardiovascular FH is important to investigate heredity in young ischemic stroke patients.

Trial Registration

ClinicalTrials.gov NCT01597453

Family History and Risk of Recurrent Stroke

Background and Purpose—

The association between family history of stroke and stroke recurrence remains unclear.

Methods—

Using a web-based multicenter stroke registry database, information on history of stroke in first-degree relatives was collected prospectively for acute ischemic stroke patients who were hospitalized within 7 days of onset. The collected information was categorized as follows: type of the affected relative(s) with stroke (paternal, maternal, sibling, or 2 or more) and age of the relative’s stroke onset (<50, 50–59, 60–69, and ≥70 years). Stroke recurrence was captured prospectively using a predetermined protocol. Subgroup analyses were performed according to the patient’s age at the index stroke.

Results—

Among 7642 patients, 937 (12.3%) had a history of stroke in their first-degree relatives and 475 (6.2%: 201 within and 274 after 3 weeks from index stroke) experienced stroke recurrence (median follow-up, 365 days). In multivariable Cox proportional hazard models, overall family history was not associated with stroke recurrence (hazard ratio, 1.08; 95% confidence interval, 0.81–1.43). However, the details of their family histories, including relative’s age at stroke onset (<50 years: hazard ratio, 2.14; 95% confidence interval, 1.004–4.54) and stroke history in a sibling (hazard ratio, 1.67; 95% confidence interval, 1.09–2.58), were independently associated with stroke recurrence after adjusting for potential confounders. The associations appeared to be stronger in young adults with stroke (age, <55 years) than in older stroke patients.

Conclusions—

This study suggests that elevated risks of recurrent stroke are associated with having relatives with early-onset stroke and siblings with stroke histories, implying that additional precautions may be needed in such populations.

TLR7 rs2897827 Polymorphism Affects TLR7 Gene mRNA Expression and Serum Apolipoprotein A1 Level of Ischemic Stroke Patients in a Chinese Han Population

Stroke is a multi-factorial disorder that has become the leading cause of death and disability worldwide. Previous studies reported that TLR7 mRNA expression is associated with poor outcome of ischemic stroke (IS). This study aimed to assess whether TLR7 mRNA expression affects IS occurrence, as well as the association of TLR7 rs2897827 with susceptibility to IS and TLR7 mRNA expression and serum apolipoprotein and lipid levels in a Chinese Han population. A total of 816 stroke patients and 816 healthy controls were included in this study. mRNA expression was determined by quantitative real-time PCR. The Sequenom MassARRAY iPLEX platform was used to genotype the TLR7 rs2897827 polymorphism. TLR7 mRNA expression of the IS cases was statistically significantly higher than that of the controls in the male or female group (male, P = 0.014; female, P = 0.025). In the male IS cases, TLR7 mRNA expression of the T allele carriers was statistically significantly higher than that of the C allele carriers (P = 0.018). However, a significant difference was not observed in the female cases (P = 0.545). In either the male or female group, the distribution of genotype or allele had no statistical significance (P > 0.050). The ApoA1 level of the T carriers was statistically significantly higher than the C carriers in males (t = -2.383, P = 0.020); however, the ApoB and lipid levels were not associated with rs2897827 (P > 0.050). In female patients, no significant difference was observed between different genotypic/allelic carriers in serum apolipoprotein and lipid levels (all P > 0.050). The expression of the TLR7 gene may affect IS occurrence. TLR7 gene rs2897827 may influence TLR7 mRNA expression and the plasma ApoA1 level in male IS patients.

Chromosome 4q25 Variants and Age at Onset of Ischemic Stroke

Recent genome-wide association studies have identified two variants rs10033464 and rs2200733 on chromosome 4q25, significantly associated with ischemic stroke risk. We conducted this study to investigate whether these two variants were associated with age at onset and prognosis of ischemic stroke in a Chinese population. Genotyping of rs10033464 and rs2200733 was performed by improved multiple ligase detection reaction. One-way ANOVA was used to compare the mean age of ischemic stroke onset for each variant. Combined effects of these two variants on age at ischemic stroke onset were then estimated. Kaplan-Meier method, log-rank test, and the Cox proportional hazards regression models were used to assess the effect of the two variants on ischemic stroke prognosis. A total of 914 ischemic stroke patients were included in the study. Rs10033464 and rs2200733 were not associated with ischemic stroke recurrence (P > 0.05). However, rs10033464 TT genotype was significantly correlated with early age of ischemic stroke onset (60.76 for GG, 61.74 for GT, 55.47 for TT, TT vs. GT: P = 0.043). Combined effects analysis revealed that mean age at ischemic stroke onset decreased with increasing genetic risk score (P = 0.038). The findings indicated that the chromosome 4q25 variants might associate with early age at onset of ischemic stroke. Further larger studies in other populations are warranted to validate our results.

Identification of PTCSC3 as a Novel Locus for Large-Vessel Ischemic Stroke: A Genome-Wide Association Study

Background

Ischemic stroke is a major cause of death and disability in the world. A major ischemic stroke subtype, large‐vessel ischemic stroke (large artery atherosclerosis; LAA), has been shown to have some genetic components in individuals of European ancestry. However, it is not clear whether the genetic predisposition to LAA stroke varies among ethnicities. We sought to identify genetic factors that contribute to LAA stroke in 2 independent samples of Han Chinese individuals.

Methods and Results

Novel genetic variants that predispose individuals to LAA stroke were identified using a genome‐wide association study (GWAS) of 444 individuals with LAA stroke and 1727 controls in a Han Chinese population residing in Taiwan. The study was replicated in an independent Han Chinese population comprising an additional 319 cases and 1802 controls. We identified 5 single‐nucleotide polymorphisms, including rs2415317 (P=3.10×10⁻⁸), rs934075 (P=4.00×10⁻⁹), rs944289 (P=3.57×10⁻⁸), rs2787417 (P=1.76×10⁻⁸), and rs1952706 (P=2.92×10⁻⁸), at one novel locus on chromosome 14q13.3 within PTCSC3 (encoding papillary thyroid carcinoma susceptibility candidate 3) that were associated with LAA stroke at genome‐wide significance (P<5×10⁻⁸).

Conclusions

Our data provide strong support for future studies on the role of PTCSC3 in the pathogenesis of LAA stroke and the association between LAA stroke development and thyroid function. In addition, these findings provide insights into the genetic basis of LAA stroke and identify a novel pathway that might be applicable for future therapeutic intervention.

Family History and Functional Outcome in Korean Stroke Patients: A Preliminary Study

OBJECTIVE

To investigate the association of family history of stroke with functional outcomes in stroke patients in Korea.

METHODS

A case-control study was conducted. A total of 170 patients who were admitted to a rehabilitation unit were included. Risk factors for stroke such as age, sex, diabetes mellitus, hypertension, atrial fibrillation, smoking, high blood cholesterol and homocysteine level, obesity, and family history of stroke were taken into account. Stroke subtypes were the following: large vessel infarct, small vessel infarct, embolic infarct, subarachnoid hemorrhage, and intracranial hemorrhage. Stroke severity as assessed with the National Institutes of Health Stroke Scale (NIHSS), functional outcomes using the Korean version of the Modified Barthel index (K-MBI), Functional Independence Measurement (FIM), and cognitive function using the Korean version of Mini-Mental State Examination (K-MMSE) were assessed at admission and discharge.

RESULTS

Subjects with a family history of stroke were more likely to have an ischemic stroke (90.7%) than were those without a family history (70.9%). The K-MBI, FIM, NIHSS, and K-MMSE scores did not show significant differences between patients with or without family history.

CONCLUSION

Family history of stroke was significantly associated with ischemic stroke, but not with functional outcomes. Other prognostic factors of stroke were not distributed differently between patients included in this study with or without a family history of stroke.

CTA Characteristics of the Circle of Willis and Intracranial Aneurysm in a Chinese Crowd with Family History of Stroke

BACKGROUND AND PURPOSE

The vascular morphology in crowd with family history of stroke remains unclear. The present study clarified the characteristics of the intracranial vascular CoW and prevalence of intracranial aneurysms in subjects with family history of stroke.

METHODS

A stratified cluster, random sampling method was used for subjects with family history of stroke among rural residents in Jixian, Tianjin, China. All the subjects underwent a physical examination, head computed tomography (CT) scan, and cephalic and cervical computed tomography angiography (CTA) scan. Anatomic variations in the Circle of Willis and cerebrovascular disease in this population were analyzed.

RESULTS

In the crowd with similar living environment, stable genetic background, and family history of stroke and without obvious nerve function impairment (1) hypoplasia or absence of A1 segment was significantly different in gender (male versus female: 9.8% versus 18.8%, p = 0.031), especially the right-side A1 (male versus female: 5.9% versus 16.4%, p = 0.004). (2) Hypoplasia or absence of bilateral posterior communicating arteries was more common in men than women (58.2% versus 45.3%, p = 0.032). Unilateral fetal posterior cerebral artery was observed more often in women than men (17.2% versus 8.5%, p = 0.028). (3) The percentage of subjects with incomplete CoW did not increase significantly with age. Compared to healthy Chinese people, the crowd had a higher percentage of incomplete CoW (p < 0.001). (4) No obvious correlation between risk factors and CoW was found. (5) The prevalence of aneurysm was 10.3% in the special crowd.

CONCLUSIONS

The certain variations of CoW showed significant relation to gender, but not to age in people with family history of stroke. The incomplete circle may be a dangerous factor that is independent of common risk factors for stroke and tend to lead to cerebral ischemia in the crowd with family history of stroke. The prevalence of intracranial aneurysm is comparatively high in the present subjects compared to other people.

Familial aggregation of stroke amongst young patients in Lund Stroke Register

BACKGROUND AND PURPOSE

The known monogenic forms of stroke are rare. The aim of this study was to analyze pedigrees of young stroke patients regarding possible monogenic cerebrovascular disease and to evaluate the possibility of genetic stroke in these families. This may contribute to a better understanding of disease mechanism in stroke.

METHODS

Lund Stroke Register includes consecutive patients with first-ever stroke from a defined geographical area in southern Sweden. Early-onset (≤55 years) stroke patients were systematically screened with regard to family history (FHx), and families with stroke aggregation were compiled. Participants provided information in a questionnaire on occurrence of stroke or transient ischaemic attack (TIA) in their families. Information on cardiovascular risk factors (VRFs) and clinical stroke subtype was collected. FHx for stroke was considered positive when the patient reported either ≥1 first-degree relative with stroke/TIA, or no first-degree relative but ≥3 second- or third-degree relatives with stroke/TIA in a distribution compatible with monogenic inheritance.

RESULTS

Of 4103 stroke patients registered, 426 (10%) had first-ever stroke at ≤55 years and 338 (79%) of these answered the questionnaire. Of them, 159 (47%) reported a positive FHx. Twenty-eight (18%) of the probands with positive FHx had no known VRFs. Thirty-two families with ≥4 members with stroke were identified. In all these larger families the affected individuals with stroke were present in more than one generation.

CONCLUSION

Aggregation of stroke in families of early-onset stroke patients is not uncommon. Genetic factors with impact on stroke risk, including monogenic causes, need to be evaluated in future stroke studies.

Variants in neuronal nitric oxide synthase gene may contribute to increased ischemic stroke susceptibility in a Han Chinese population

Variants in neuronal NOS (nNOS) gene were associated with atherosclerosis and stroke susceptibility. We aimed to investigate the association between nNOS gene polymorphism and risk of ischemic stroke caused by small-artery occlusion (SAO) and large-artery atherosclerosis (LAA) in a Chinese population. We conducted a case-control study involving 381 ischemic stroke patients and 366 healthy subjects. Selected SNPs (rs1483757, rs2293050, and rs2139733) were genotyped and assessed; the association with the risk of ischemic stroke was analyzed. Furthermore, gender- and etiologic subtype-stratified analyses were also carried out to evaluate the association between nNOS polymorphisms and risk of ischemic stroke. No significant difference was observed between selected nNOS loci and risk of ischemic stroke in alleles or any genetic models in total study population, males or females, adjusted with age, drinking and smoking status. Rs2293050 and rs2139733 genotypes were associated with total cholesterol (rs2293050, P = 0.026; rs2139733, P = 0.040) and LDL (rs2293050, P = 0.031; rs2139733, P = 0.046) in females. A significant difference in allele distribution of rs2293050 (P = 0.040) and a marginally significant difference of rs2139733 (P = 0.061) in LAA-caused ischemic stroke cases and controls were observed in total population. No association between rs1483757 and ischemic stroke was found in this study. T allele of rs2293050 and A allele of rs2139733 in nNOS gene may contribute to increased susceptibility of LAA-caused ischemic stroke in Han Chinese.

Heritability of young- and old-onset ischaemic stroke

BACKGROUND AND PURPOSE

Although the genetic contribution to stroke risk is well known, it remains unclear if young-onset stroke has a stronger genetic contribution than old-onset stroke. This study aims to compare the heritability of ischaemic stroke risk between young and old, using common genetic variants from whole-genome array data in population-based samples.

METHODS

This analysis included 4050 ischaemic stroke cases and 5765 controls from six study populations of European ancestry; 47% of cases were young-onset stroke (age < 55 years). To quantify the heritability for stroke risk in these unrelated individuals, the pairwise genetic relatedness was estimated between individuals based on their whole-genome array data using a mixed linear model. Heritability was estimated separately for young-onset stroke and old-onset stroke (age ≥ 55 years).

RESULTS

Heritabilities for young-onset stroke and old-onset stroke were estimated at 42% (±8%, P < 0.001) and 34% (±10%, P < 0.001), respectively.

CONCLUSIONS

Our data suggest that the genetic contribution to the risk of stroke may be higher in young-onset ischaemic stroke, although the difference was not statistically significant.

Prevalence of CADASIL and Fabry Disease in a Cohort of MRI Defined Younger Onset Lacunar Stroke

Background and Purpose

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), caused by mutations in the NOTCH3 gene, is the most common monogenic disorder causing lacunar stroke and cerebral small vessel disease (SVD). Fabry disease (FD) due to mutations in the GLA gene has been suggested as an underdiagnosed cause of stroke, and one feature is SVD. Previous studies reported varying prevalence of CADASIL and FD in stroke, likely due to varying subtypes studied; no studies have looked at a large cohort of younger onset SVD. We determined the prevalence in a well-defined, MRI-verified cohort of apparently sporadic patients with lacunar infarct.

Methods

Caucasian patients with lacunar infarction, aged ≤70 years (mean age 56.7 (SD8.6)), were recruited from 72 specialist stroke centres throughout the UK as part of the Young Lacunar Stroke DNA Resource. Patients with a previously confirmed monogenic cause of stroke were excluded. All MRI’s and clinical histories were reviewed centrally. Screening was performed for NOTCH3 and GLA mutations.

Results

Of 994 subjects five had pathogenic NOTCH3 mutations (R169C, R207C, R587C, C1222G and C323S) all resulting in loss or gain of a cysteine in the NOTCH3 protein. All five patients had confluent leukoaraiosis (Fazekas grade ≥2). CADASIL prevalence overall was 0.5% (95% CI 0.2%-1.1%) and among cases with confluent leukoaraiosis 1.5% (95% CI 0.6%-3.3%). No classic pathogenic FD mutations were found; one patient had a missense mutation (R118C), associated with late-onset FD.

Conclusion

CADASIL cases are rare and only detected in SVD patients with confluent leukoaraiosis. No definite FD cases were detected.

Genetic Architecture of Lacunar Stroke

Supplemental Digital Content is available in the text.

Lacunar strokes comprise ≈20% of all strokes. Despite this frequency, their pathogenesis is poorly understood. Previous genome-wide association studies in lacunar stroke have been disappointing, which may be because of phenotypic heterogeneity. Pathological and radiological studies suggest that there may be different pathologies underlying lacunar strokes. This has led to the suggestion of 2 subtypes: isolated lacunar infarcts and multiple lacunar infarcts and leukoaraiosis.

Genetic Factors Influencing Coagulation Factor XIII B-Subunit Contribute to Risk of Ischemic Stroke

Background and Purpose—

Abnormal coagulation has been implicated in the pathogenesis of ischemic stroke, but how this association is mediated and whether it differs between ischemic stroke subtypes is unknown. We determined the shared genetic risk between 14 coagulation factors and ischemic stroke and its subtypes.

Methods—

Using genome-wide association study results for 14 coagulation factors from the population-based TwinsUK sample (N≈2000 for each factor), meta-analysis results from the METASTROKE consortium ischemic stroke genome-wide association study (12 389 cases, 62 004 controls), and genotype data for 9520 individuals from the WTCCC2 ischemic stroke study (3548 cases, 5972 controls—the largest METASTROKE subsample), we explored shared genetic risk for coagulation and stroke. We performed three analyses: (1) a test for excess concordance (or discordance) in single nucleotide polymorphism effect direction across coagulation and stroke, (2) an estimation of the joint effect of multiple coagulation-associated single nucleotide polymorphisms in stroke, and (3) an evaluation of common genetic risk between coagulation and stroke.

Results—

One coagulation factor, factor XIII subunit B (FXIIIB), showed consistent effects in the concordance analysis, the estimation of polygenic risk, and the validation with genotype data, with associations specific to the cardioembolic stroke subtype. Effect directions for FXIIIB-associated single nucleotide polymorphisms were significantly discordant with cardioembolic disease (smallest P=5.7×10⁻⁰⁴); the joint effect of FXIIIB-associated single nucleotide polymorphisms was significantly predictive of ischemic stroke (smallest P=1.8×10⁻⁰⁴) and the cardioembolic subtype (smallest P=1.7×10⁻⁰⁴). We found substantial negative genetic covariation between FXIIIB and ischemic stroke (rG=−0.71, P=0.01) and the cardioembolic subtype (rG=−0.80, P=0.03).

Conclusions—

Genetic markers associated with low FXIIIB levels increase risk of ischemic stroke cardioembolic subtype.

Family History in Young Patients With Stroke

BACKGROUND AND PURPOSE

Family history of stroke is an established risk factor for stroke. We evaluated whether family history of stroke predisposed to certain stroke subtypes and whether it differed by sex in young patients with stroke.

METHODS

We used data from the Stroke in Fabry Patients study, a large prospective, hospital-based, screening study for Fabry disease in young patients (aged <55 years) with stroke in whom cardiovascular risk factors and family history of stroke were obtained and detailed stroke subtyping was performed.

RESULTS

A family history of stroke was present in 1578 of 4232 transient ischemic attack and ischemic stroke patients (37.3%). Female patients more often had a history of stroke in the maternal lineage (P=0.027) than in the paternal lineage. There was no association with stroke subtype according to Trial of Org 10172 in Acute Stroke Treatment nor with the presence of white matter disease on brain imaging. Patients with dissection less frequently reported a family history of stroke (30.4% versus 36.3%; P=0.018). Patients with a parental history of stroke more commonly had siblings with stroke (3.6% versus 2.6%; P=0.047).

CONCLUSIONS

Although present in about a third of patients, a family history of stroke is not specifically related to stroke pathogenic subtypes in patients with young stroke. Young women with stroke more often report stroke in the maternal lineage.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00414583.

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.