@article {6556, title = {Effect of genetic variants associated with plasma homocysteine levels on stroke risk.}, journal = {Stroke}, volume = {45}, year = {2014}, month = {2014 Jul}, pages = {1920-4}, abstract = {

BACKGROUND AND PURPOSE: Elevated total plasma homocysteine (tHcy) levels are known to be associated with increased risk of ischemic stroke (IS). Given that both tHcy and IS are heritable traits, we investigated a potential genetic relationship between homocysteine levels and stroke risk by assessing 18 polymorphisms previously associated with tHcy levels for their association with IS and its subtypes.

METHODS: Previous meta-analysis results from an international stroke collaborative network, METASTROKE, were used to assess association of the 18 tHcy-associated single-nucleotide polymorphisms (SNPs) in 12 389 IS cases and 62 004 controls. We also investigated the associations in regions located within 50 kb from the 18 tHcy-related SNPs and the association of a genetic risk score, including the 18 SNPs.

RESULTS: One SNP located in the RASIP1 gene and a cluster of 3 SNPs located at and near SLC17A3 were significantly associated with IS (P<0.0003) after correcting for multiple testing. For stroke subtypes, the sentinel SNP located upstream of MUT was significantly associated with small-vessel disease (P=0.0022), whereas 1 SNP located in MTHFR was significantly associated with large-vessel disease (P=0.00019). A genetic risk score, including the 18 SNPs, did not show significant association with IS or its subtypes.

CONCLUSIONS: This study found several potential associations with IS and its subtypes: an association of an MUT variant with small-vessel disease, an MTHFR variant with large-vessel disease, and associations of RASIP1 and SLC17A3 variants with overall IS.

}, keywords = {Brain Ischemia, Cohort Studies, Europe, Genetic Association Studies, Genetic Loci, Genetic Predisposition to Disease, Genetic Variation, Genome, Homocysteine, Humans, Polymorphism, Single Nucleotide, Risk, Stroke}, issn = {1524-4628}, doi = {10.1161/STROKEAHA.114.005208}, author = {Cotlarciuc, Ioana and Malik, Rainer and Holliday, Elizabeth G and Ahmadi, Kourosh R and Par{\'e}, Guillaume and Psaty, Bruce M and Fornage, Myriam and Hasan, Nazeeha and Rinne, Paul E and Ikram, M Arfan and Markus, Hugh S and Rosand, Jonathan and Mitchell, Braxton D and Kittner, Steven J and Meschia, James F and van Meurs, Joyce B J and Uitterlinden, Andr{\'e} G and Worrall, Bradford B and Dichgans, Martin and Sharma, Pankaj} } @article {6297, title = {Multilocus genetic risk score associates with ischemic stroke in case-control and prospective cohort studies.}, journal = {Stroke}, volume = {45}, year = {2014}, month = {2014 Feb}, pages = {394-402}, abstract = {

BACKGROUND AND PURPOSE: Genome-wide association studies have revealed multiple common variants associated with known risk factors for ischemic stroke (IS). However, their aggregate effect on risk is uncertain. We aimed to generate a multilocus genetic risk score (GRS) for IS based on genome-wide association studies data from clinical-based samples and to establish its external validity in prospective population-based cohorts.

METHODS: Three thousand five hundred forty-eight clinic-based IS cases and 6399 controls from the Wellcome Trust Case Control Consortium 2 were used for derivation of the GRS. Subjects from the METASTROKE consortium served as a replication sample. The validation sample consisted of 22 751 participants from the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium. We selected variants that had reached genome-wide significance in previous association studies on established risk factors for IS.

RESULTS: A combined GRS for atrial fibrillation, coronary artery disease, hypertension, and systolic blood pressure significantly associated with IS both in the case-control samples and in the prospective population-based studies. Subjects in the top quintile of the combined GRS had >2-fold increased risk of IS compared with subjects in the lowest quintile. Addition of the combined GRS to a simple model based on sex significantly improved the prediction of IS in the combined clinic-based samples but not in the population-based studies, and there was no significant improvement in net reclassification.

CONCLUSIONS: A multilocus GRS based on common variants for established cardiovascular risk factors was significantly associated with IS both in clinic-based samples and in the general population. However, the improvement in clinical risk prediction was found to be small.

}, keywords = {Adult, Aged, Aged, 80 and over, Atrial Fibrillation, Blood Pressure, Brain Ischemia, Case-Control Studies, Cohort Studies, Coronary Artery Disease, Female, Genetic Predisposition to Disease, Genetic Variation, Genome-Wide Association Study, Humans, Hypertension, Male, Middle Aged, Multilocus Sequence Typing, Polymorphism, Single Nucleotide, Population, Prospective Studies, Reproducibility of Results, Risk Assessment, Risk Factors, Sex Factors, Stroke}, issn = {1524-4628}, doi = {10.1161/STROKEAHA.113.002938}, author = {Malik, Rainer and Bevan, Steve and Nalls, Michael A and Holliday, Elizabeth G and Devan, William J and Cheng, Yu-Ching and Ibrahim-Verbaas, Carla A and Verhaaren, Benjamin F J and Bis, Joshua C and Joon, Aron Y and de Stefano, Anita L and Fornage, Myriam and Psaty, Bruce M and Ikram, M Arfan and Launer, Lenore J and van Duijn, Cornelia M and Sharma, Pankaj and Mitchell, Braxton D and Rosand, Jonathan and Meschia, James F and Levi, Christopher and Rothwell, Peter M and Sudlow, Cathie and Markus, Hugh S and Seshadri, Sudha and Dichgans, Martin} } @article {6688, title = {Genetic overlap between diagnostic subtypes of ischemic stroke.}, journal = {Stroke}, volume = {46}, year = {2015}, month = {2015 Mar}, pages = {615-9}, abstract = {

BACKGROUND AND PURPOSE: Despite moderate heritability, the phenotypic heterogeneity of ischemic stroke has hampered gene discovery, motivating analyses of diagnostic subtypes with reduced sample sizes. We assessed evidence for a shared genetic basis among the 3 major subtypes: large artery atherosclerosis (LAA), cardioembolism, and small vessel disease (SVD), to inform potential cross-subtype analyses.

METHODS: Analyses used genome-wide summary data for 12 389 ischemic stroke cases (including 2167 LAA, 2405 cardioembolism, and 1854 SVD) and 62 004 controls from the Metastroke consortium. For 4561 cases and 7094 controls, individual-level genotype data were also available. Genetic correlations between subtypes were estimated using linear mixed models and polygenic profile scores. Meta-analysis of a combined LAA-SVD phenotype (4021 cases and 51 976 controls) was performed to identify shared risk alleles.

RESULTS: High genetic correlation was identified between LAA and SVD using linear mixed models (rg=0.96, SE=0.47, P=9{\texttimes}10(-4)) and profile scores (rg=0.72; 95\% confidence interval, 0.52-0.93). Between LAA and cardioembolism and SVD and cardioembolism, correlation was moderate using linear mixed models but not significantly different from zero for profile scoring. Joint meta-analysis of LAA and SVD identified strong association (P=1{\texttimes}10(-7)) for single nucleotide polymorphisms near the opioid receptor μ1 (OPRM1) gene.

CONCLUSIONS: Our results suggest that LAA and SVD, which have been hitherto treated as genetically distinct, may share a substantial genetic component. Combined analyses of LAA and SVD may increase power to identify small-effect alleles influencing shared pathophysiological processes.

}, keywords = {Alleles, Atherosclerosis, Cerebral Small Vessel Diseases, Cohort Studies, Data Interpretation, Statistical, Embolism, Genome-Wide Association Study, Genotype, Humans, Ischemia, Linear Models, Meta-Analysis as Topic, Phenotype, Polymorphism, Single Nucleotide, Stroke}, issn = {1524-4628}, doi = {10.1161/STROKEAHA.114.007930}, author = {Holliday, Elizabeth G and Traylor, Matthew and Malik, Rainer and Bevan, Steve and Falcone, Guido and Hopewell, Jemma C and Cheng, Yu-Ching and Cotlarciuc, Ioana and Bis, Joshua C and Boerwinkle, Eric and Boncoraglio, Giorgio B and Clarke, Robert and Cole, John W and Fornage, Myriam and Furie, Karen L and Ikram, M Arfan and Jannes, Jim and Kittner, Steven J and Lincz, Lisa F and Maguire, Jane M and Meschia, James F and Mosley, Thomas H and Nalls, Mike A and Oldmeadow, Christopher and Parati, Eugenio A and Psaty, Bruce M and Rothwell, Peter M and Seshadri, Sudha and Scott, Rodney J and Sharma, Pankaj and Sudlow, Cathie and Wiggins, Kerri L and Worrall, Bradford B and Rosand, Jonathan and Mitchell, Braxton D and Dichgans, Martin and Markus, Hugh S and Levi, Christopher and Attia, John and Wray, Naomi R} } @article {6812, title = {Meta-Analysis of Genome-Wide Association Studies Identifies Genetic Risk Factors for Stroke in African Americans.}, journal = {Stroke}, volume = {46}, year = {2015}, month = {2015 Aug}, pages = {2063-8}, abstract = {

BACKGROUND AND PURPOSE: The majority of genome-wide association studies (GWAS) of stroke have focused on European-ancestry populations; however, none has been conducted in African Americans, despite the disproportionately high burden of stroke in this population. The Consortium of Minority Population Genome-Wide Association Studies of Stroke (COMPASS) was established to identify stroke susceptibility loci in minority populations.

METHODS: Using METAL, we conducted meta-analyses of GWAS in 14 746 African Americans (1365 ischemic and 1592 total stroke cases) from COMPASS, and tested genetic variants with P<10(-6) for validation in METASTROKE, a consortium of ischemic stroke genetic studies in European-ancestry populations. We also evaluated stroke loci previously identified in European-ancestry populations.

RESULTS: The 15q21.3 locus linked with lipid levels and hypertension was associated with total stroke (rs4471613; P=3.9{\texttimes}10(-8)) in African Americans. Nominal associations (P<10(-6)) for total or ischemic stroke were observed for 18 variants in or near genes implicated in cell cycle/mRNA presplicing (PTPRG, CDC5L), platelet function (HPS4), blood-brain barrier permeability (CLDN17), immune response (ELTD1, WDFY4, and IL1F10-IL1RN), and histone modification (HDAC9). Two of these loci achieved nominal significance in METASTROKE: 5q35.2 (P=0.03), and 1p31.1 (P=0.018). Four of 7 previously reported ischemic stroke loci (PITX2, HDAC9, CDKN2A/CDKN2B, and ZFHX3) were nominally associated (P<0.05) with stroke in COMPASS.

CONCLUSIONS: We identified a novel genetic variant associated with total stroke in African Americans and found that ischemic stroke loci identified in European-ancestry populations may also be relevant for African Americans. Our findings support investigation of diverse populations to identify and characterize genetic risk factors, and the importance of shared genetic risk across populations.

}, keywords = {African Americans, Case-Control Studies, Cohort Studies, Genetic Predisposition to Disease, Genome-Wide Association Study, Humans, Polymorphism, Single Nucleotide, Risk Factors, Stroke}, issn = {1524-4628}, doi = {10.1161/STROKEAHA.115.009044}, author = {Carty, Cara L and Keene, Keith L and Cheng, Yu-Ching and Meschia, James F and Chen, Wei-Min and Nalls, Mike and Bis, Joshua C and Kittner, Steven J and Rich, Stephen S and Tajuddin, Salman and Zonderman, Alan B and Evans, Michele K and Langefeld, Carl D and Gottesman, Rebecca and Mosley, Thomas H and Shahar, Eyal and Woo, Daniel and Yaffe, Kristine and Liu, Yongmei and Sale, Mich{\`e}le M and Dichgans, Martin and Malik, Rainer and Longstreth, W T and Mitchell, Braxton D and Psaty, Bruce M and Kooperberg, Charles and Reiner, Alexander and Worrall, Bradford B and Fornage, Myriam} }