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Objective: Stroke risk factors often exert long-term effects, and Mendelian randomization (MR) offers significant advantages over traditional observational studies in evaluating the causal impact of these factors on stroke. This study aims to consolidate and evaluate the relationships between potential causal factors and stroke risk, drawing upon existing MR research. Methods: A comprehensive search for MR studies related to stroke was conducted up to August 2023 using databases such as PubMed, Web of Science, Embase, and Scopus. This meta-analysis examines the relationships between potential causative factors and stroke risk. Both random-effects and fixed-effects models were utilized to compile the dominance ratios of various causative elements linked to stroke. The reliability of the included studies was assessed according to the Strengthening the Reporting of Observational Studies in Epidemiology incorporating Mendelian Randomization (STROBE-MR) guidelines. Results: The analysis identified several risk factors for stroke, including obesity, hypertension, low-density lipoprotein cholesterol (LDL-C), chronic kidney disease (CKD), and smoking. Protective factors included high-density lipoprotein cholesterol (HDL-C), estimated glomerular filtration rate (eGFR), and educational attainment. Subgroup analysis revealed that type 2 diabetes mellitus (T2DM), diastolic blood pressure (DBP) are risk factors for ischemic stroke (IS). Conclusion: This study confirms that variables such as obesity, hypertension, elevated LDL-C levels, CKD, and smoking are significantly linked to the development of stroke. Our findings provide new insights into genetic susceptibility and potential biological pathways involved in stroke development. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO , identifier CRD42024503049. [ABSTRACT FROM AUTHOR]

Background: Ischemic stroke (IS) is a global health issue linked to lipid metabolism and immune cell responses. This study uses Mendelian randomization (MR) to identify genetic risk factors for IS subtypes using comprehensive genetic data from lipidomic and immune cell profiles. Methods: We assessed genetic susceptibility to IS across 179 lipids and 731 immune cell phenotypes using instrumental variables (IVs) from recent genome-wide association studies. A two-sample MR approach evaluated correlations, and a two-step MR mediation analysis explored the role of immune cell phenotypes in the lipid-IS pathway. Sensitivity analyses, including MR-Egger and Cochran Q tests, ensured robust results. Results: Genetic IVs for 162 lipids and 614 immune cell phenotypes were identified. Significant genetic causality was found between 35 lipids and large artery stroke (LAS), with 12 as risk factors (sterol esters, phosphatidylcholines, phosphatidylethanolamines) and 23 as protective factors (phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols). For small vessel stroke (SVS), 8 as risk factors (sterol esters, phosphatidylcholines), and 2 as protective factors (phosphatidylinositol, sphingomyelin). For cardioembolic stroke (CS), 2 as risk factors, and 4 as protective factors. Mediation analysis revealed that CCR2 on granulocytes, CD11c on CD62L+ myeloid dendritic cells, and FSC-A on granulocytes mediated the lipid-immune cell-LAS pathway, while CD4 on activated CD4 regulatory T cells and CD4 on activated & secreting CD4 regulatory T cells mediated the lipid-immune cell-SVS pathway. Conclusion: This study identifies genetic links between specific lipids and IS subtypes, highlights immune cells' role in IS risk and mediation, suggests new therapeutic targets, and uncovers IS genetic drivers. [ABSTRACT FROM AUTHOR]

Background: Ischemic stroke (IS) is a global health issue linked to lipid metabolism and immune cell responses. This study uses Mendelian randomization (MR) to identify genetic risk factors for IS subtypes using comprehensive genetic data from lipidomic and immune cell profiles. Methods: We assessed genetic susceptibility to IS across 179 lipids and 731 immune cell phenotypes using instrumental variables (IVs) from recent genome- wide association studies. A two-sample MR approach evaluated correlations, and a two-step MR mediation analysis explored the role of immune cell phenotypes in the lipid-IS pathway. Sensitivity analyses, including MR-Egger and Cochran Q tests, ensured robust results. Results: Genetic IVs for 162 lipids and 614 immune cell phenotypes were identified. Significant genetic causality was found between 35 lipids and large artery stroke (LAS), with 12 as risk factors (sterol esters, phosphatidylcholines, phosphatidylethanolamines) and 23 as protective factors (phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols). For small vessel stroke (SVS), 8 as risk factors (sterol esters, phosphatidylcholines), and 2 as protective factors (phosphatidylinositol, sphingomyelin). For cardioembolic stroke (CS), 2 as risk factors, and 4 as protective factors. Mediation analysis revealed that CCR2 on granulocytes, CD11c on CD62L+ myeloid dendritic cells, and FSC-A on granulocytes mediated the lipid-immune cell-LAS pathway, while CD4 on activated CD4 regulatory T cells and CD4 on activated & secreting CD4 regulatory T cells mediated the lipid-immune cell-SVS pathway. Conclusion: This study identifies genetic links between specific lipids and IS subtypes, highlights immune cells’ role in IS risk and mediation, suggests new therapeutic targets, and uncovers IS genetic drivers. [ABSTRACT FROM AUTHOR]

Background: Metabolomics is increasingly being utilized in IS research to elucidate the intricate metabolic alterations that occur during ischemic stroke (IS). However, establishing causality in these associations remains unclear between metabolites and IS subtypes. In this study, we employ Mendelian randomization (MR) to identify specific metabolites and investigate potential causal relationships between metabolites and IS subtypes. Methods: MR analysis was conducted using genome-wide association study (GWAS) summary data. We obtained 1,091 blood metabolites and 309 metabolite ratios from the GWAS Catalog (GCST90199621-90201020), which gene sequencing data from 8,299 individuals from the Canadian Longitudinal Study. We obtained GWAS summary statistics for IS subtypes which include large artery stroke (LAS), cardioembolic stroke (CES), and small vessel stroke (SVS) from the MEGASTROKE consortium that included 446,696 cases of European ancestry and 406,111 controls of European ancestry. The primary analysis utilized inverse-variance weighted (IVW) method. To validate our results, we performed supplementary analyses employing the MR-Egger, weighted median, simple mode, and weighted mode methods. Heterogeneity and pleiotropy were assessed through Cochran’s Q test, MR-Egger intercept test, and leave-one-out analysis. Results: The study assessed the possible causality of serum metabolites in the risk of IS subtypes. The discovery of significant causal links between 33 metabolites and 3 distinct IS subtypes. Conclusion: Metabolites show significant potential as circulating metabolic biomarkers and offer promise for clinical applications in the prevention and screening of IS subtypes. These discoveries notably advance our comprehension of the molecular processes specific to IS subtypes and create avenues for investigating targeted treatment approaches in the future. [ABSTRACT FROM AUTHOR]

Background: Observational researches have suggested a connection between iron deficiency anemia (IDA) and an increased likelihood of ischemic stroke (IS), yet establishing causality is challenging owing to the inherent limitations of such studies, including their vulnerability to confounding factors and the potential for reverse causation. This study employs a bidirectional two-sample Mendelian randomization (MR) approach to assess the causal linkage between IDA and IS and its subtypes. Methods: Identifiable single nucleotide polymorphisms (SNPs) with significant links to either IDA or IS and its subtypes were employed as instrumental variables (IVs). The relationship between IDA and any IS, small vessel stroke (SVS), cardioembolic stroke (CES), and large artery stroke (LAS), was quantified using the inverse variance weighted (IVW) method. Complementary analyses utilizing MR-Egger and weighted median methods further supplemented the IVW findings. Moreover, the leave-one-out analysis, MR-Egger intercept test, MR-PRESSO global test, and Cochrane's Q test were conducted for sensitivity analyses. Results: This study revealed no correlation between IDA and any IS (IVW method: OR [95% CI] = 0.977 [0.863-1.106]; p = 0.716), LAS (OR [95% CI] = 1.158 [0.771-1.740]; p = 0.479), CES (OR [95% CI] = 1.065 [0.882-1.285]; p = 0.512), or SVS (OR [95% CI] = 1.138 [0.865-1.498]; p = 0.357). Conducting a reverse MR analysis, it was determined that there is no causal connection between any IS, LAS, CES, SVS, and IDA (all p > 0.05). Sensitivity analysis indicated that heterogeneity was not significant and no evidence of horizontal pleiotropy was detected. Conclusion: This MR study suggested no causal effect of IDA on IS, LAS, CES, and SVS. Through reverse MR analyses, it was determined that IS and its subtypes did not exert a causal impact on IDA. [ABSTRACT FROM AUTHOR]

ObjectiveStroke risk factors often exert long-term effects, and Mendelian randomization (MR) offers significant advantages over traditional observational studies in evaluating the causal impact of these factors on stroke. This study aims to consolidate and evaluate the relationships between potential causal factors and stroke risk, drawing upon existing MR research.MethodsA comprehensive search for MR studies related to stroke was conducted up to August 2023 using databases such as PubMed, Web of Science, Embase, and Scopus. This meta-analysis examines the relationships between potential causative factors and stroke risk. Both random-effects and fixed-effects models were utilized to compile the dominance ratios of various causative elements linked to stroke. The reliability of the included studies was assessed according to the Strengthening the Reporting of Observational Studies in Epidemiology incorporating Mendelian Randomization (STROBE-MR) guidelines.ResultsThe analysis identified several risk factors for stroke, including obesity, hypertension, low-density lipoprotein cholesterol (LDL-C), chronic kidney disease (CKD), and smoking. Protective factors included high-density lipoprotein cholesterol (HDL-C), estimated glomerular filtration rate (eGFR), and educational attainment. Subgroup analysis revealed that type 2 diabetes mellitus (T2DM), diastolic blood pressure (DBP) are risk factors for ischemic stroke (IS).ConclusionThis study confirms that variables such as obesity, hypertension, elevated LDL-C levels, CKD, and smoking are significantly linked to the development of stroke. Our findings provide new insights into genetic susceptibility and potential biological pathways involved in stroke development.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO, identifier CRD42024503049.

Introduction: Stroke is one of the common diseases that pose a severe threat to human health, with immune cells playing a crucial role in its onset and recovery. However, the specific mechanisms and causal relationships of different immune cell groups in various clinical stroke subtypes are unclear. This study explored the causal relationship between immune cells and stroke and its subtypes using Mendelian randomization (MR) analysis. Methods: Data from genome-wide association studies were analyzed using inverse-variance weighted (IVW), MR-Egger, and weighted median methods for MR analysis, along with heterogeneity tests, sensitivity analysis, and pleiotropy analysis. Results: CD45RA+CD28−CD8+ T cell %T cell (OR 1.002, 95% CI 1.001–1.003; PFDR = 0.02), CD27 on CD24+CD27+ B cell (OR 1.127, 95% CI 1.061–1.198; PFDR = 0.04), CD27 on IgD−CD38dim B cell (OR 1.138, 95% CI 1.076–1.203; PFDR = 0.005), and CD27 on switched memory B cell (OR 1.144, 95% CI 1.076–1.216; PFDR = 0.01) were found to increase the risk of large artery stroke. Switched memory B cell %lymphocyte (OR 1.206, 95% CI 1.103–1.318; PFDR = 0.02) increased the risk of small vessel stroke. Reverse MR analysis did not reveal any reverse causal associations. Furthermore, by substituting the outcome data, a secondary MR analysis was conducted to validate the primary findings. Conclusion: Our study reveals several causal links between immune phenotypes and stroke and its different subtypes, highlighting the complex interactions between the immune system and stroke. These findings provide new directions for further uncovering the biological basis of stroke and assist in advancing research on early interventions and treatment strategies. [ABSTRACT FROM AUTHOR]

Background: Stroke is a devastating global health issue, with high mortality and disability rates. The increasing prevalence of male infertility among reproductive-aged men has become a growing concern worldwide. However, the relationship between male infertility and stroke incidence remains uncertain. This study aimed to address this knowledge gap by employing a Mendelian randomization (MR) approach. Method: Utilizing genetic instrumental variables derived from a genome-wide association study (GWAS) on male infertility and stroke, a two-sample MR design was implemented. Five different analysis methods, with inverse-variance weighted as the primary approach, were used to examine the genetic causal associations between male infertility and various stroke subtypes. Heterogeneity analysis, pleiotropy tests, and leave-one-out validation were conducted to assess heterogeneity, evaluate pleiotropy, and ensure the robustness of the findings. Result: The results indicate a potential lower risk of small vessel stroke associated with male infertility (odds ratio, 95% confidence interval: 0.82, 0.68 to 0.99, p=0.044), although no significant impact on other stroke subtypes was observed. The study exhibited low heterogeneity and no apparent pleiotropy; however, the stability of the results was not optimal. Conclusion: Male infertility might potentially confer a protective effect against small vessel stroke risk. Caution is warranted due to potential confounding factors. Additional studies are necessary to confirm these findings and provide further validation. [ABSTRACT FROM AUTHOR]

Background Serum lipids are causally involved in the occurrence of atherosclerosis, but their roles in cerebral small vessel disease remain unclear. This study aimed to investigate the causal roles of lipid or apolipoprotein traits in cerebral small vessel disease and to determine the effects of lipid‐lowering interventions on this disease. Methods and Results Data on genetic instruments of lipids/apolipoproteins, as well as characteristic cerebral small vessel disease manifestations, including small vessel stroke (SVS) and white matter hyperintensity (WMH), were obtained from publicly genome‐wide association studies. Through 2‐sample Mendelian randomization analyses, it was found that decreased levels of high‐density lipoprotein cholesterol (odds ratio [OR], 0.85, P=0.007) and apolipoprotein A‐I (OR, 0.83, P=0.005), as well as increased level of triglycerides (OR, 1.16, P=0.025) were associated with a higher risk of SVS. A low level of high‐density lipoprotein cholesterol (OR, 0.93, P=0.032) was associated with larger WMH volume. Specifically, the genetically determined expressions of lipid fractions in various size‐defined lipoprotein particles were more closely related to the risk of SVS than WMH. Moreover, it was found that the hypertension trait ranked at the top in mediating the causal effect of hyperlipidemia on SVS and WMH by using Mendelian randomization‐based mediation analysis. For drug‐target Mendelian randomization, the low‐density lipoprotein cholesterol‐reducing genetic variation alleles at HMGCR and NL1CL1 genes and the high‐density lipoprotein cholesterol‐raising genetic variation alleles at the CETP gene were predicted to decrease the risk of SVS. Conclusions The present Mendelian randomization study indicates that genetically determined hyperlipidemia is closely associated with a higher risk of cerebral small vessel disease, especially SVS. Lipid‐lowering drugs could be potentially considered for the therapies and preventions of SVS rather than WMH.

Abstract Background Stroke is a common neurological disorder that disproportionately affects middle-aged and elderly individuals, leading to significant disability and mortality. Recently, human blood metabolites have been discovered to be useful in unraveling the underlying biological mechanisms of neurological disorders. Therefore, we aimed to evaluate the causal relationship between human blood metabolites and susceptibility to stroke. Methods Summary data from genome-wide association studies (GWASs) of serum metabolites and stroke and its subtypes were obtained separately. A total of 486 serum metabolites were used as the exposure. Simultaneously, 11 different stroke phenotypes were set as the outcomes, including any stroke (AS), any ischemic stroke (AIS), large artery stroke (LAS), cardioembolic stroke (CES), small vessel stroke (SVS), lacunar stroke (LS), white matter hyperintensities (WMH), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), transient ischemic attack (TIA), and brain microbleeds (BMB). A two‐sample Mendelian randomization (MR) study was conducted to investigate the causal effects of serum metabolites on stroke and its subtypes. The inverse variance-weighted MR analyses were conducted as causal estimates, accompanied by a series of sensitivity analyses to evaluate the robustness of the results. Furthermore, a reverse MR analysis was conducted to assess the potential for reverse causation. Additionally, metabolic pathway analysis was performed using the web-based MetOrigin. Results After correcting for the false discovery rate (FDR), MR analysis results revealed remarkable causative associations with 25 metabolites. Further sensitivity analyses confirmed that only four causative associations involving three specific metabolites passed all sensitivity tests, namely ADpSGEGDFXAEGGGVR* for AS (OR: 1.599, 95% CI 1.283–1.993, p = 2.92 × 10−5) and AIS (OR: 1.776, 95% CI 1.380–2.285, p = 8.05 × 10−6), 1-linoleoylglycerophosph-oethanolamine* for LAS (OR: 0.198, 95% CI 0.091–0.428, p = 3.92 × 10−5), and gamma-glutamylmethionine* for SAH (OR: 3.251, 95% CI 1.876–5.635, p = 2.66 × 10−5), thereby demonstrating a high degree of stability. Moreover, eight causative associations involving seven other metabolites passed both sensitivity tests and were considered robust. The association result of one metabolite (glutamate for LAS) was considered non-robust. As for the remaining metabolites, we speculate that they may potentially possess underlying causal relationships. Notably, no common metabolites emerged from the reverse MR analysis. Moreover, after FDR correction, metabolic pathway analysis identified 40 significant pathways across 11 stroke phenotypes. Conclusions The identified metabolites and their associated metabolic pathways are promising circulating metabolic biomarkers, holding potential for their application in stroke screening and preventive strategies within clinical settings.

Background: Stroke is a common neurological disorder that disproportionately affects middle-aged and elderly individuals, leading to significant disability and mortality. Recently, human blood metabolites have been discovered to be useful in unraveling the underlying biological mechanisms of neurological disorders. Therefore, we aimed to evaluate the causal relationship between human blood metabolites and susceptibility to stroke. Methods: Summary data from genome-wide association studies (GWASs) of serum metabolites and stroke and its subtypes were obtained separately. A total of 486 serum metabolites were used as the exposure. Simultaneously, 11 different stroke phenotypes were set as the outcomes, including any stroke (AS), any ischemic stroke (AIS), large artery stroke (LAS), cardioembolic stroke (CES), small vessel stroke (SVS), lacunar stroke (LS), white matter hyperintensities (WMH), intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), transient ischemic attack (TIA), and brain microbleeds (BMB). A two‐sample Mendelian randomization (MR) study was conducted to investigate the causal effects of serum metabolites on stroke and its subtypes. The inverse variance-weighted MR analyses were conducted as causal estimates, accompanied by a series of sensitivity analyses to evaluate the robustness of the results. Furthermore, a reverse MR analysis was conducted to assess the potential for reverse causation. Additionally, metabolic pathway analysis was performed using the web-based MetOrigin. Results: After correcting for the false discovery rate (FDR), MR analysis results revealed remarkable causative associations with 25 metabolites. Further sensitivity analyses confirmed that only four causative associations involving three specific metabolites passed all sensitivity tests, namely ADpSGEGDFXAEGGGVR* for AS (OR: 1.599, 95% CI 1.283–1.993, p = 2.92 × 10−5) and AIS (OR: 1.776, 95% CI 1.380–2.285, p = 8.05 × 10−6), 1-linoleoylglycerophosph-oethanolamine* for LAS (OR: 0.198, 95% CI 0.091–0.428, p = 3.92 × 10−5), and gamma-glutamylmethionine* for SAH (OR: 3.251, 95% CI 1.876–5.635, p = 2.66 × 10−5), thereby demonstrating a high degree of stability. Moreover, eight causative associations involving seven other metabolites passed both sensitivity tests and were considered robust. The association result of one metabolite (glutamate for LAS) was considered non-robust. As for the remaining metabolites, we speculate that they may potentially possess underlying causal relationships. Notably, no common metabolites emerged from the reverse MR analysis. Moreover, after FDR correction, metabolic pathway analysis identified 40 significant pathways across 11 stroke phenotypes. Conclusions: The identified metabolites and their associated metabolic pathways are promising circulating metabolic biomarkers, holding potential for their application in stroke screening and preventive strategies within clinical settings. [ABSTRACT FROM AUTHOR]

Background Chitinase‐3 like protein 1 (CHI3L1, YKL‐40) was reported to be implicated in the development of ischemic stroke, but whether the association between them was causal remained unclear. We conducted a 2‐sample Mendelian randomization study to explore the associations of genetically determined plasma YKL‐40 with ischemic stroke and its subtypes (large artery stroke, small vessel stroke, and cardioembolic stroke). Methods and Results Based on genome‐wide association study data of 3394 European‐descent individuals, we selected 13 single‐nucleotide polymorphisms associated with plasma YKL‐40 as genetic instruments. Summary data about ischemic stroke and its subtypes were obtained from the Multiancestry Genome‐wide Association Study of Stroke Consortium, involving 34 217 ischemic stroke cases and 406 111 controls of European ancestry. We used the inverse‐variance weighted method followed by a series of sensitivity analyses to assess the causal associations of plasma YKL‐40 with ischemic stroke and its subtypes. The primary analysis showed that genetically determined high YKL‐40 levels were associated with increased risks of large artery stroke (odds ratio [OR], 1.08 [95% CI, 1.04–1.12]; P=1.73×10−4) and small vessel stroke (OR, 1.05 [95% CI, 1.01–1.09]; P=7.96×10−3) but not with ischemic stroke or cardioembolic stroke. Sensitivity analyses further confirmed these associations, and Mendelian randomization‐Egger indicated no evidence of genetic pleiotropy. In addition, supplementary analysis based on the summary data from the Olink proximity extension assay cardiovascular I (Olink CVD‐I) panel showed that high YKL‐40 levels were positively associated with the risks of large artery stroke (OR, 1.15 [95% CI, 1.08–1.22]; P=4.16×10−6) but not with small vessel stroke. Conclusions Genetically determined high plasma YKL‐40 levels were causal associated with increased risks of large artery stroke.

BackgroundPrevious studies have suggested a potential association between nutrients and cerebral small vessel disease (CSVD), but this association has not been fully addressed.ObjectWe intended to clarify the causal associations between four categories of essential nutrients (amino acids, polyunsaturated fatty acids, minerals and vitamins) and two acute manifestations of CSVD (intracerebral hemorrhage and small vessel stroke) using two-sample Mendelian randomization (MR) analysis.MethodWe obtained European-based large-scale genome-wide association studies (GWASs) related to CSVD (6,255 cases and 233,058 controls) and nutrient concentrations. Causality evaluation mainly included the results of the inverse variance-weighted (IVW) method. The simple median method, the weighted median method and the MR–Egger method were adopted for sensitivity analyses.ResultsFor ICH or SVS, increased levels of phenylalanine (OR = 1.188, p

Background: Multiple risk factors of stroke have been identified in previous studies; however, the causal role of snoring in the onset of stroke is less investigated. To clarify the causal association of snoring on stroke and its subtypes, this study is performed. Methods: The single nucleotide polymorphisms in relation to snoring were retrieved from the UK biobank cohort with 408,317 participants. The data for stroke and its subtypes of European ancestry (67,162 cases and 453,702 controls) were obtained fromtheMEGASTROKE consortium. In single-variable Mendelian randomization (SVMR) and multivariable MR (MVMR) analyses, inverse variance weighting was used as the primary estimate, complemented with sensitivity analyses more robust to pleiotropy. Results: Genetically predicted snoring increased the risk of stroke (odds ratio [OR] = 2.69, 95% confidence interval [CI] = 1.19-6.08, P = 0.016) and ischemic stroke (IS) (OR = 2.82, 95% CI = 1.23-6.44, P = 0.013), but not large artery stroke (LAS) (OR = 3.02, 95% CI = 0.31-29.44, P = 0.339), cardioembolic stroke (CES) (OR = 1.51, 95% CI = 0.58-3.92, P = 0.395). We provide novel genetic evidence that snoring increases the risk of stroke and IS, but not LAS, CES, and SVS. Conclusion: Our findings provide novel genetic evidence that snoring increases the risk of stroke and IS, but not LAS, CES, and SVS. [ABSTRACT FROM AUTHOR]

Cerebral small vessel disease (cSVD) causes lacunar stroke (LS), intracerebral haemorrhage, and is the most common pathology underlying vascular dementia. However, there are few trials examining whether treating conventional cardiovascular risk factors reduce stroke risk in cSVD, as opposed to stroke as a whole. We used Mendelian randomization techniques to investigate which risk factors are causally related to cSVD and to evaluate whether specific drugs may be beneficial in cSVD prevention. We identified genetic proxies for blood pressure traits, lipids, glycaemic markers, anthropometry measures, smoking, alcohol consumption, and physical activity from large-scale genome-wide association studies of European ancestry. We also selected genetic variants as proxies for drug target perturbation in hypertension, dyslipidaemia, hyperglycaemia, and obesity. Mendelian randomization was performed to assess their associations with LS from the GIGASTROKE Consortium (n = 6811) and in a sensitivity analysis in a cohort of patients with MRI-confirmed LS (n = 3306). We also investigated associations with three neuroimaging features of cSVD, namely, white matter hyperintensities (n = 55 291), fractional anisotropy (n = 36 460), and mean diffusivity (n = 36 012). Genetic predisposition to higher systolic and diastolic blood pressure was associated with LS and cSVD imaging markers. Genetically predicted liability to diabetes, obesity, smoking, higher triglyceride levels, and the ratio of triglycerides to high density lipoprotein (HDL) also showed detrimental associations with LS risk, while genetic predisposition to higher HDL concentrations and moderate-to-vigorous physical activity showed protective associations. Genetically proxied blood pressure-lowering through calcium channel blockers (CCBs) was associated with cSVD imaging markers, while genetically proxied HDL-raising through Cholesteryl Ester Transfer Protein (CETP) inhibitors, triglyceride-lowering through lipoprotein lipase (LPL), and weight-lowering through gastric inhibitory polypeptide receptor (GIPR) were associated with lower risk of LS. Our findings highlight the importance of some conventional cardiovascular risk factors, including blood pressure and BMI, in cSVD, but not other e.g. LDL. The findings further demonstrate the potential beneficial effects of CCBs on cSVD imaging markers and CETP inhibitors, LPL enhancement, and GIPR obesity-targeted drugs on LS. They provide useful information for initiating future clinical trials examining secondary prevention strategies in cSVD., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Small vessel strokes (SVS) and intracerebral haemorrhages (ICH) are acute outcomes of cerebral small vessel disease (SVD). Genetic studies combining both phenotypes have identified three loci associated with both traits. However, the genetic cis-regulation at the protein level associated with SVD has not been studied before. We performed a proteome-wide association study (PWAS) using FUSION to integrate a genome-wide association study (GWAS) and brain proteomic data to discover the common mechanisms regulating both SVS and ICH. Dorsolateral prefrontal cortex (dPFC) brain proteomes from the ROS/MAP study (N = 376 subjects and 1443 proteins) and the summary statistics for the SVS GWAS from the MEGASTROKE study (N = 237,511) and multi-trait analysis of GWAS (MTAG)-ICH–SVS from Chung et al. (N = 240,269) were selected. We performed PWAS and then a co-localization analysis with COLOC. The significant and nominal results were validated using a replication dPFC proteome (N = 152). The replicated results (q-value < 0.05) were further investigated for the causality relationship using summary data-based Mendelian randomization (SMR). One protein (ICA1L) was significantly associated with SVS (z-score = −4.42 and p-value = 9.6 × 10−6) and non-lobar ICH (z-score = −4.8 and p-value = 1.58 × 10−6) in the discovery PWAS, with a high co-localization posterior probability of 4. In the validation PWAS, ICA1L remained significantly associated with both traits. The SMR results for ICA1L indicated a causal association of protein expression levels in the brain with SVS (p-value = 3.66 × 10−5) and non-lobar ICH (p-value = 1.81 × 10−5). Our results show that the association of ICA1L with SVS and non-lobar ICH is conditioned by the cis-regulation of its protein levels in the brain. [ABSTRACT FROM AUTHOR]

Background and purpose: The causal effect of insulin resistance on small vessel stroke and Alzheimer's disease (AD) was controversial in previous studies. We therefore applied Mendelian randomization (MR) analyses to identify the causal effect of insulin resistance on small vessel stroke and AD. Methods: We selected 12 single‐nucleotide polymorphisms (SNPs) associated with fasting insulin levels and five SNPs associated with "gold standard" measures of insulin resistance as instrumental variables in MR analyses. Summary statistical data on SNP–small vessel stroke and on SNP–AD associations were derived from studies by the Multi‐ancestry Genome‐Wide Association Study of Stroke consortium (MEGASTROKE) and the Psychiatric Genomics Consortium‐Alzheimer Disease Workgroup (PGC‐ALZ) in individuals of European ancestry. Two‐sample MR estimates were conducted with inverse‐variance‐weighted, robust inverse‐variance‐weighted, simple median, weighted median, weighted mode‐based estimator, and MR pleiotropy residual sum and outlier (MR‐PRESSO) methods. Results: Genetically predicted higher insulin resistance had a higher odds ratio (OR) of small vessel stroke (OR 1.23, 95% confidence interval [CI] 1.05–1.44, p = 0.01 using fasting insulin; OR 1.25, 95% CI 1.07–1.46, p = 0.006 using gold standard measures of insulin resistance) and AD (OR 1.13, 95% CI 1.04–1.23, p = 0.004 using fasting insulin; OR 1.02, 95% CI 1.00–1.03, p = 0.03 using gold standard measures of insulin resistance) using the inverse‐variance‐weighted method. No evidence of pleiotropy was found using MR‐Egger regression. Conclusion: Our findings provide genetic support for a potential causal effect of insulin resistance on small vessel stroke and AD. [ABSTRACT FROM AUTHOR]

Background: Metabolomics is increasingly being utilized in IS research to elucidate the intricate metabolic alterations that occur during ischemic stroke (IS). However, establishing causality in these associations remains unclear between metabolites and IS subtypes. In this study, we employ Mendelian randomization (MR) to identify specific metabolites and investigate potential causal relationships between metabolites and IS subtypes., Methods: MR analysis was conducted using genome-wide association study (GWAS) summary data. We obtained 1,091 blood metabolites and 309 metabolite ratios from the GWAS Catalog (GCST90199621-90201020), which gene sequencing data from 8,299 individuals from the Canadian Longitudinal Study. We obtained GWAS summary statistics for IS subtypes which include large artery stroke (LAS), cardioembolic stroke (CES), and small vessel stroke (SVS) from the MEGASTROKE consortium that included 446,696 cases of European ancestry and 406,111 controls of European ancestry. The primary analysis utilized inverse-variance weighted (IVW) method. To validate our results, we performed supplementary analyses employing the MR-Egger, weighted median, simple mode, and weighted mode methods. Heterogeneity and pleiotropy were assessed through Cochran's Q test, MR-Egger intercept test, and leave-one-out analysis., Results: The study assessed the possible causality of serum metabolites in the risk of IS subtypes. The discovery of significant causal links between 33 metabolites and 3 distinct IS subtypes., Conclusion: Metabolites show significant potential as circulating metabolic biomarkers and offer promise for clinical applications in the prevention and screening of IS subtypes. These discoveries notably advance our comprehension of the molecular processes specific to IS subtypes and create avenues for investigating targeted treatment approaches in the future., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zhang, Wang, Zhao, Ma, Shen and Zhu.)

Background: Serum lipids are causally involved in the occurrence of atherosclerosis, but their roles in cerebral small vessel disease remain unclear. This study aimed to investigate the causal roles of lipid or apolipoprotein traits in cerebral small vessel disease and to determine the effects of lipid-lowering interventions on this disease., Methods and Results: Data on genetic instruments of lipids/apolipoproteins, as well as characteristic cerebral small vessel disease manifestations, including small vessel stroke (SVS) and white matter hyperintensity (WMH), were obtained from publicly genome-wide association studies. Through 2-sample Mendelian randomization analyses, it was found that decreased levels of high-density lipoprotein cholesterol (odds ratio [OR], 0.85, P =0.007) and apolipoprotein A-I (OR, 0.83, P =0.005), as well as increased level of triglycerides (OR, 1.16, P =0.025) were associated with a higher risk of SVS. A low level of high-density lipoprotein cholesterol (OR, 0.93, P =0.032) was associated with larger WMH volume. Specifically, the genetically determined expressions of lipid fractions in various size-defined lipoprotein particles were more closely related to the risk of SVS than WMH. Moreover, it was found that the hypertension trait ranked at the top in mediating the causal effect of hyperlipidemia on SVS and WMH by using Mendelian randomization-based mediation analysis. For drug-target Mendelian randomization, the low-density lipoprotein cholesterol-reducing genetic variation alleles at HMGCR and NL1CL1 genes and the high-density lipoprotein cholesterol-raising genetic variation alleles at the CETP gene were predicted to decrease the risk of SVS., Conclusions: The present Mendelian randomization study indicates that genetically determined hyperlipidemia is closely associated with a higher risk of cerebral small vessel disease, especially SVS. Lipid-lowering drugs could be potentially considered for the therapies and preventions of SVS rather than WMH.

Background: Observational researches have suggested a connection between iron deficiency anemia (IDA) and an increased likelihood of ischemic stroke (IS), yet establishing causality is challenging owing to the inherent limitations of such studies, including their vulnerability to confounding factors and the potential for reverse causation. This study employs a bidirectional two-sample Mendelian randomization (MR) approach to assess the causal linkage between IDA and IS and its subtypes., Methods: Identifiable single nucleotide polymorphisms (SNPs) with significant links to either IDA or IS and its subtypes were employed as instrumental variables (IVs). The relationship between IDA and any IS, small vessel stroke (SVS), cardioembolic stroke (CES), and large artery stroke (LAS), was quantified using the inverse variance weighted (IVW) method. Complementary analyses utilizing MR-Egger and weighted median methods further supplemented the IVW findings. Moreover, the leave-one-out analysis, MR-Egger intercept test, MR-PRESSO global test, and Cochrane's Q test were conducted for sensitivity analyses., Results: This study revealed no correlation between IDA and any IS (IVW method: OR [95% CI] = 0.977 [0.863-1.106]; p  = 0.716), LAS (OR [95% CI] = 1.158 [0.771-1.740]; p  = 0.479), CES (OR [95% CI] = 1.065 [0.882-1.285]; p  = 0.512), or SVS (OR [95% CI] = 1.138 [0.865-1.498]; p  = 0.357). Conducting a reverse MR analysis, it was determined that there is no causal connection between any IS, LAS, CES, SVS, and IDA (all p  > 0.05). Sensitivity analysis indicated that heterogeneity was not significant and no evidence of horizontal pleiotropy was detected., Conclusion: This MR study suggested no causal effect of IDA on IS, LAS, CES, and SVS. Through reverse MR analyses, it was determined that IS and its subtypes did not exert a causal impact on IDA., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Chen, Li, Zhou and Yao.)

A colocalization analysis of genome-wide association study (GWAS) signals and expression quantitative trait loci (eQTL) was conducted to pinpoint target genes and their regulatory nucleotide variants for subtypes of ischemic stroke. We utilized GWAS data from prominent meta-analysis consortia (MEGASTROKE and GIGASTROKE) and single-cell eQTL data in brain and blood tissues to enhance accuracy and minimize noise inherent in bulk RNA-seq. Employing Bayesian colocalization methods, we identified ten shared loci between GWAS and eQTL signals, targeting five eGenes. Specifically, RAPH1 and ICA1L were discovered for small vessel stroke (SVS), whereas SCYL3, CAV1, and CAV2 were for cardioembolic stroke (CS). However, no findings have been made for large artery stroke. The exploration and subsequent functional analysis of causal variants within the colocalized regions revealed their regulatory roles, particularly as enhancer variants (e.g., rs144505847 and rs72932755 targeting ICA1L; rs629234 targeting SCYL3; rs3807989 targeting CAV1 and CAV2). Notably, our study unveiled that all eQTL for CS were identified in oligodendrocytes, while those for SVS were across excitatory neurons, astrocytes, and oligodendrocyte precursor cells. This underscores the heterogeneous tissue-specific genetic factors by subtypes of ischemic stroke. The study emphasizes the need for intensive research efforts to discover causative genes and variants, unravelling the cell type-specific genetic architecture of ischemic stroke subtypes. This knowledge is crucial for advancing our understanding of the underlying pathophysiology and paving the way for precision neurology applications. [Display omitted] • RAPH1 and ICA1L are noteworthy genes for susceptibility to small vessel stroke. • SCYL3, CAV1, and CAV2 are noteworthy genes for susceptibility to cardioembolic stroke. • Genetic factors for cardioembolic stroke were all identified in oligodendrocytes. • Sequence variants in stroke GWAS signals regulate gene expression, largely as enhancers. [ABSTRACT FROM AUTHOR]

We sought to examine the frequency of depression after small vessel-type stroke (SVS) and associated risk factors. We conducted a retrospective analysis of a prospective cohort of patients enrolled in the American Stroke Association-Bugher SVS Study, which included 200 participants within 2-years of SVS and 79 controls without a history of stroke from 2007 to 2012 at four sites. The primary outcome was PHQ-8, with scores ≥10 consistent with post-stroke depression (PSD). A logistic regression adjusted for age, race, sex, history of diabetes and Short-Form Montreal Cognitive Assessment score (SF-MoCA) was used to compare the risk of having depression after SVS compared to controls. Another logistic regression, adjusted for age, sex, race, level of education, SF-MoCA, white matter disease (WMD) burden, stroke severity (NIHSS), time between stroke and depression screen, history of diabetes, and history of hypertension was used to identify factors independently associated with depression in participants with SVS. The cohort included 161 participants with SVS (39 excluded due to missing data) and 79 controls. The mean interval between stroke and depression screening was 74 days. Among participants with SVS, 31.7% (n = 51) had PSD compared to 6.3% (n = 5) of controls (RR = 5.44, 95% CI = 2.21-13.38, p = 0.0002). The only two variables independently associated with PSD in participants with SVS were female sex (RR = 1.84, 95% CI = 1.09-3.09, p = 0.020) and diabetes (RR 1.69, 95% CI 1.03-2.79). After adjusting for several demographic and clinical variables, having a SVS was associated with an approximate 5-fold increased risk of depression and was more frequent in women and in those with diabetes. The extent of WMD was not independently associated with PSD, suggesting that small vessel disease in the setting of an overt SVS may not account for the increased prevalence of depression. [ABSTRACT FROM AUTHOR]

Background: Stroke is a devastating global health issue, with high mortality and disability rates. The increasing prevalence of male infertility among reproductive-aged men has become a growing concern worldwide. However, the relationship between male infertility and stroke incidence remains uncertain. This study aimed to address this knowledge gap by employing a Mendelian randomization (MR) approach., Method: Utilizing genetic instrumental variables derived from a genome-wide association study (GWAS) on male infertility and stroke, a two-sample MR design was implemented. Five different analysis methods, with inverse-variance weighted as the primary approach, were used to examine the genetic causal associations between male infertility and various stroke subtypes. Heterogeneity analysis, pleiotropy tests, and leave-one-out validation were conducted to assess heterogeneity, evaluate pleiotropy, and ensure the robustness of the findings., Result: The results indicate a potential lower risk of small vessel stroke associated with male infertility (odds ratio, 95% confidence interval: 0.82, 0.68 to 0.99, p =0.044), although no significant impact on other stroke subtypes was observed. The study exhibited low heterogeneity and no apparent pleiotropy; however, the stability of the results was not optimal., Conclusion: Male infertility might potentially confer a protective effect against small vessel stroke risk. Caution is warranted due to potential confounding factors. Additional studies are necessary to confirm these findings and provide further validation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zhu, Xin, Yu, Guan, Wang, Liu, Dong and Ye.)

Background and purpose: Although observational studies have reported a positive association between depression and ischemic stroke, causality remains inconclusive. We aimed to assess the causal relationship of major depressive disorder (MDD) with ischemic stroke, especially with the small vessel stroke (SVS) subtype. Methods: We used 72 independent single-nucleotide polymorphisms associated with MDD in a genome-wide association study (GWAS) from the Psychiatric Genetics Consortium as instrumental variables. The corresponding data for ischemic stroke and its subtypes of European ancestry were available from the MEGASTROKE consortium of 34,217 ischemic stroke cases and 406,111 controls. Primary Mendelian randomization estimates were calculated with inverse-variance weighted method, and several alternate methods and multiple sensitivity analyses were also performed. Results: We found that genetic predisposition to higher risk of MDD was associated with higher risk of SVS, with an odds ratio of 1.33 (95% confidence interval, 1.08–1.65; p = 0.009) per log-odds increment in MDD risk, but not with large artery stroke (OR, 1.08; 95% CI 0.83–1.41; p = 0.559), cardioembolic stroke (OR, 0.98; 95% CI 0.80–1.20; p = 0.833), or all ischemic stroke (OR, 1.03; 95% CI 0.92–1.15; p = 0.633). The association of MDD with SVS was overall robust to sensitivity analyses. Conclusions: We provided evidence for a possible causal effect of MDD on increased risk of SVS. Future researches are required to investigate whether rational intervention on depression may help to reduce societal burden of SVS. [ABSTRACT FROM AUTHOR]

Background Chitinase-3 like protein 1 (CHI3L1, YKL-40) was reported to be implicated in the development of ischemic stroke, but whether the association between them was causal remained unclear. We conducted a 2-sample Mendelian randomization study to explore the associations of genetically determined plasma YKL-40 with ischemic stroke and its subtypes (large artery stroke, small vessel stroke, and cardioembolic stroke). Methods and Results Based on genome-wide association study data of 3394 European-descent individuals, we selected 13 single-nucleotide polymorphisms associated with plasma YKL-40 as genetic instruments. Summary data about ischemic stroke and its subtypes were obtained from the Multiancestry Genome-wide Association Study of Stroke Consortium, involving 34 217 ischemic stroke cases and 406 111 controls of European ancestry. We used the inverse-variance weighted method followed by a series of sensitivity analyses to assess the causal associations of plasma YKL-40 with ischemic stroke and its subtypes. The primary analysis showed that genetically determined high YKL-40 levels were associated with increased risks of large artery stroke (odds ratio [OR], 1.08 [95% CI, 1.04-1.12]; P =1.73×10 -4 ) and small vessel stroke (OR, 1.05 [95% CI, 1.01-1.09]; P =7.96×10 -3 ) but not with ischemic stroke or cardioembolic stroke. Sensitivity analyses further confirmed these associations, and Mendelian randomization-Egger indicated no evidence of genetic pleiotropy. In addition, supplementary analysis based on the summary data from the Olink proximity extension assay cardiovascular I (Olink CVD-I) panel showed that high YKL-40 levels were positively associated with the risks of large artery stroke (OR, 1.15 [95% CI, 1.08-1.22]; P =4.16×10 -6 ) but not with small vessel stroke. Conclusions Genetically determined high plasma YKL-40 levels were causal associated with increased risks of large artery stroke.

Background: Previous studies have suggested a potential association between nutrients and cerebral small vessel disease (CSVD), but this association has not been fully addressed., Object: We intended to clarify the causal associations between four categories of essential nutrients (amino acids, polyunsaturated fatty acids, minerals and vitamins) and two acute manifestations of CSVD (intracerebral hemorrhage and small vessel stroke) using two-sample Mendelian randomization (MR) analysis., Method: We obtained European-based large-scale genome-wide association studies (GWASs) related to CSVD (6,255 cases and 233,058 controls) and nutrient concentrations. Causality evaluation mainly included the results of the inverse variance-weighted (IVW) method. The simple median method, the weighted median method and the MR-Egger method were adopted for sensitivity analyses., Results: For ICH or SVS, increased levels of phenylalanine (OR = 1.188, p  < 0.001) and dihomo-gamma-linolenic acid (DGLA) (OR = 1.153, p  = 0.001) showed risk effects, while docosapentaenoic acid (DPA) (OR = 0.501, p  < 0.001), zinc (OR = 0.919, p  < 0.001), and arachidonic acid (OR = 0.966, p  = 0.007) showed protective effects. For lobar hemorrhage or SVS, AA (OR = 0.978, p  < 0.001), zinc (OR = 0.918, p  < 0.001), and retinol (OR = 0.753, p  < 0.001) showed risk effects; DPA (OR = 0.682, p  = 0.022), gamma-linolenic acid (OR = 0.120, p  = 0.033) and 25(OH)D (OR = 0.874, p  = 0.040) showed protective effects. For nonlobar hemorrhage or SVS, DGLA (OR = 1.088, p  < 0.001) and phenylalanine (OR = 1.175, p  = 0.001) showed risk effects., Conclusion: Our study analyzed the effect of nutrients on CSVD risk from a genetic perspective, with implications for CSVD prevention through nutrient supplementation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Li, Xia, Wang, Liu, Tong, Wang, Zhou, Zhang, Tang, Fan and Yang.)

This study explored the clinical profile, risk factors, neuroimaging and outcome of childhood basal ganglia stroke. Children (6 months-12 years) with basal ganglia stroke registered between 2007-2011 were retrospectively enrolled, while newly diagnosed cases over the 2-year study period were enrolled prospectively. Children with recent trivial head trauma were compared with those without it. Of the 35 children enrolled, trivial head trauma was seen in 74%. The non–trivial head trauma group (n = 9) comprised unidentified etiology (4), Moyamoya syndrome (2), varicella infection (1), homocysteinemia (1), and probable mitochondrial cytopathy (1). Median duration to complete recovery was significantly less in the trivial head trauma group (median = 12, range = 1-72 weeks vs median = 38, range = 20-48 weeks, P = .001). Moreover, these children had increased chances of complete recovery (85% [22/26] vs 44.5% [4/9], P = .029). Basal ganglia stroke can follow trivial head trauma and may have a more favorable outcome. [ABSTRACT FROM AUTHOR]

Stroke is a multi-factorial disease caused by a combination of genetic and environmental factors. The purpose of this case control study was to determine the relationship of beta-1 adrenergic receptor polymorphism with ischemic stroke in North Indian population. In this study, 224 patients and 224 age- and sex-matched controls were recruited from the outpatient department and neurology ward of All India Institute of Medical Sciences, New Delhi. Genotyping was performed by using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) method. PCR results were confirmed by DNA sequencing. Frequency distributions of genotypes and alleles were compared between cases and controls using logistic regression. Mean age of cases and controls was 53.9 ± 13.4 and 53.6 ± 12.9 years respectively. Multivariate logistic regression analysis showed an independent association between Ser49Gly polymorphism and ischemic stroke under a dominant model of inheritance (OR, 2.5; 95% CI, 1.2 to 5) and large vessel disease (LVD) under a recessive model of inheritance (OR, 6.5; 95% CI, 1.7 to 23; P = 0.005). Independent association of Arg389Gly polymorphism with small vessel disease (SVD) (OR, 7.09; 95% CI, 1.9 to 25; P = 0.003) under recessive model of inheritance. The findings of the present study Ser49Gly polymorphism of the ADRB1 gene confer higher risk of ischemic stroke in a North Indian population and especially in patients with LVD. Our findings also show that Arg389Gly polymorphism of ADRB1 confers higher risk of SVD in North Indian population. [ABSTRACT FROM AUTHOR]

Background: Multiple risk factors of stroke have been identified in previous studies; however, the causal role of snoring in the onset of stroke is less investigated. To clarify the causal association of snoring on stroke and its subtypes, this study is performed., Methods: The single nucleotide polymorphisms in relation to snoring were retrieved from the UK biobank cohort with 408,317 participants. The data for stroke and its subtypes of European ancestry (67,162 cases and 453,702 controls) were obtained from the MEGASTROKE consortium. In single-variable Mendelian randomization (SVMR) and multivariable MR (MVMR) analyses, inverse variance weighting was used as the primary estimate, complemented with sensitivity analyses more robust to pleiotropy., Results: Genetically predicted snoring increased the risk of stroke (odds ratio [OR] = 2.69, 95% confidence interval [CI] = 1.19-6.08, P = 0.016) and ischemic stroke (IS) (OR = 2.82, 95% CI = 1.23-6.44, P = 0.013), but not large artery stroke (LAS) (OR = 3.02, 95% CI = 0.31-29.44, P = 0.339), cardioembolic stroke (CES) (OR = 1.51, 95% CI = 0.58-3.92, P = 0.395). We provide novel genetic evidence that snoring increases the risk of stroke and IS, but not LAS, CES, and SVS., Conclusion: Our findings provide novel genetic evidence that snoring increases the risk of stroke and IS, but not LAS, CES, and SVS., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 He, Ren, Li, Wang, Tao, Ma and You.)

Background: Monoallelic and biallelic mutations in the exonuclease TREX1 cause monogenic small vessel diseases (SVD). Given recent evidence for genetic and pathophysiological overlap between monogenic and polygenic forms of SVD, evaluation of TREX1 in small vessel stroke is warranted. Methods: We sequenced the TREX1 gene in an exploratory cohort of patients with lacunar stroke (Edinburgh Stroke Study, n=290 lacunar stroke cases). We subsequently performed a fully blinded case-control study of early onset MRI-confirmed small vessel stroke within the UK Young Lacunar Stroke Resource (990 cases, 939 controls). Results: No patients with canonical disease-causing mutations of TREX1 were identified in cases or controls. Analysis of an exploratory cohort identified a potential association between rare variants of TREX1 and patients with lacunar stroke. However, subsequent controlled and blinded evaluation of TREX1 in a larger and MRI-confirmed patient cohort, the UK Young Lacunar Stroke Resource, identified heterozygous rare variants in 2.1% of cases and 2.3% of controls. No association was observed with stroke risk (odds ratio = 0.90; 95% confidence interval, 0.49-1.65 p=0.74). Similarly no association was seen with rare TREX1 variants with predicted deleterious effects on enzyme function (odds ratio = 1.05; 95% confidence interval, 0.43-2.61 p=0.91). Conclusions: No patients with early-onset lacunar stroke had genetic evidence of a TREX1 -associated monogenic microangiopathy. These results show no evidence of association between rare variants of TREX1 and early onset lacunar stroke. This includes rare variants that significantly affect protein and enzyme function. Routine sequencing of the TREX1 gene in patients with early onset lacunar stroke is therefore unlikely to be of diagnostic utility, in the absence of syndromic features or family history., Competing Interests: No competing interests were disclosed.