@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 {6220, title = {Predicting stroke through genetic risk functions: the CHARGE Risk Score Project.}, journal = {Stroke}, volume = {45}, year = {2014}, month = {2014 Feb}, pages = {403-12}, abstract = {

BACKGROUND AND PURPOSE: Beyond the Framingham Stroke Risk Score, prediction of future stroke may improve with a genetic risk score (GRS) based on single-nucleotide polymorphisms associated with stroke and its risk factors.

METHODS: The study includes 4 population-based cohorts with 2047 first incident strokes from 22,720 initially stroke-free European origin participants aged >=55 years, who were followed for up to 20 years. GRSs were constructed with 324 single-nucleotide polymorphisms implicated in stroke and 9 risk factors. The association of the GRS to first incident stroke was tested using Cox regression; the GRS predictive properties were assessed with area under the curve statistics comparing the GRS with age and sex, Framingham Stroke Risk Score models, and reclassification statistics. These analyses were performed per cohort and in a meta-analysis of pooled data. Replication was sought in a case-control study of ischemic stroke.

RESULTS: In the meta-analysis, adding the GRS to the Framingham Stroke Risk Score, age and sex model resulted in a significant improvement in discrimination (all stroke: Δjoint area under the curve=0.016, P=2.3{\texttimes}10(-6); ischemic stroke: Δjoint area under the curve=0.021, P=3.7{\texttimes}10(-7)), although the overall area under the curve remained low. In all the studies, there was a highly significantly improved net reclassification index (P<10(-4)).

CONCLUSIONS: The single-nucleotide polymorphisms associated with stroke and its risk factors result only in a small improvement in prediction of future stroke compared with the classical epidemiological risk factors for stroke.

}, keywords = {Age Factors, Aged, Aged, 80 and over, Area Under Curve, Case-Control Studies, Cohort Studies, European Continental Ancestry Group, Female, Genetic Predisposition to Disease, Genome-Wide Association Study, Genotype, Humans, Male, Middle Aged, Polymorphism, Single Nucleotide, Regression Analysis, Risk Factors, ROC Curve, Sex Factors, Stroke}, issn = {1524-4628}, doi = {10.1161/STROKEAHA.113.003044}, author = {Ibrahim-Verbaas, Carla A and Fornage, Myriam and Bis, Joshua C and Choi, Seung Hoan and Psaty, Bruce M and Meigs, James B and Rao, Madhu and Nalls, Mike and Fontes, Jo{\~a}o D and O{\textquoteright}Donnell, Christopher J and Kathiresan, Sekar and Ehret, Georg B and Fox, Caroline S and Malik, Rainer and Dichgans, Martin and Schmidt, Helena and Lahti, Jari and Heckbert, Susan R and Lumley, Thomas and Rice, Kenneth and Rotter, Jerome I and Taylor, Kent D and Folsom, Aaron R and Boerwinkle, Eric and Rosamond, Wayne D and Shahar, Eyal and Gottesman, Rebecca F and Koudstaal, Peter J and Amin, Najaf and Wieberdink, Renske G and Dehghan, Abbas and Hofman, Albert and Uitterlinden, Andr{\'e} G and DeStefano, Anita L and Debette, Stephanie and Xue, Luting and Beiser, Alexa and Wolf, Philip A and DeCarli, Charles and Ikram, M Arfan and Seshadri, Sudha and Mosley, Thomas H and Longstreth, W T and van Duijn, Cornelia M and Launer, Lenore J} } @article {6683, title = {Multiethnic genome-wide association study of cerebral white matter hyperintensities on MRI.}, journal = {Circ Cardiovasc Genet}, volume = {8}, year = {2015}, month = {2015 Apr}, pages = {398-409}, abstract = {

BACKGROUND: The burden of cerebral white matter hyperintensities (WMH) is associated with an increased risk of stroke, dementia, and death. WMH are highly heritable, but their genetic underpinnings are incompletely characterized. To identify novel genetic variants influencing WMH burden, we conducted a meta-analysis of multiethnic genome-wide association studies.

METHODS AND RESULTS: We included 21 079 middle-aged to elderly individuals from 29 population-based cohorts, who were free of dementia and stroke and were of European (n=17 936), African (n=1943), Hispanic (n=795), and Asian (n=405) descent. WMH burden was quantified on MRI either by a validated automated segmentation method or a validated visual grading scale. Genotype data in each study were imputed to the 1000 Genomes reference. Within each ethnic group, we investigated the relationship between each single-nucleotide polymorphism and WMH burden using a linear regression model adjusted for age, sex, intracranial volume, and principal components of ancestry. A meta-analysis was conducted for each ethnicity separately and for the combined sample. In the European descent samples, we confirmed a previously known locus on chr17q25 (P=2.7{\texttimes}10(-19)) and identified novel loci on chr10q24 (P=1.6{\texttimes}10(-9)) and chr2p21 (P=4.4{\texttimes}10(-8)). In the multiethnic meta-analysis, we identified 2 additional loci, on chr1q22 (P=2.0{\texttimes}10(-8)) and chr2p16 (P=1.5{\texttimes}10(-8)). The novel loci contained genes that have been implicated in Alzheimer disease (chr2p21 and chr10q24), intracerebral hemorrhage (chr1q22), neuroinflammatory diseases (chr2p21), and glioma (chr10q24 and chr2p16).

CONCLUSIONS: We identified 4 novel genetic loci that implicate inflammatory and glial proliferative pathways in the development of WMH in addition to previously proposed ischemic mechanisms.

}, keywords = {Aged, Aged, 80 and over, Chromosomes, Human, Continental Population Groups, Female, Genetic Loci, Genome-Wide Association Study, Humans, Male, Meta-Analysis as Topic, Middle Aged, Models, Genetic, Stroke, White Matter}, issn = {1942-3268}, doi = {10.1161/CIRCGENETICS.114.000858}, author = {Verhaaren, Benjamin F J and Debette, Stephanie and Bis, Joshua C and Smith, Jennifer A and Ikram, M Kamran and Adams, Hieab H and Beecham, Ashley H and Rajan, Kumar B and Lopez, Lorna M and Barral, Sandra and van Buchem, Mark A and van der Grond, Jeroen and Smith, Albert V and Hegenscheid, Katrin and Aggarwal, Neelum T and de Andrade, Mariza and Atkinson, Elizabeth J and Beekman, Marian and Beiser, Alexa S and Blanton, Susan H and Boerwinkle, Eric and Brickman, Adam M and Bryan, R Nick and Chauhan, Ganesh and Chen, Christopher P L H and Chouraki, Vincent and de Craen, Anton J M and Crivello, Fabrice and Deary, Ian J and Deelen, Joris and De Jager, Philip L and Dufouil, Carole and Elkind, Mitchell S V and Evans, Denis A and Freudenberger, Paul and Gottesman, Rebecca F and Gu{\dh}nason, Vilmundur and Habes, Mohamad and Heckbert, Susan R and Heiss, Gerardo and Hilal, Saima and Hofer, Edith and Hofman, Albert and Ibrahim-Verbaas, Carla A and Knopman, David S and Lewis, Cora E and Liao, Jiemin and Liewald, David C M and Luciano, Michelle and van der Lugt, Aad and Martinez, Oliver O and Mayeux, Richard and Mazoyer, Bernard and Nalls, Mike and Nauck, Matthias and Niessen, Wiro J and Oostra, Ben A and Psaty, Bruce M and Rice, Kenneth M and Rotter, Jerome I and von Sarnowski, Bettina and Schmidt, Helena and Schreiner, Pamela J and Schuur, Maaike and Sidney, Stephen S and Sigurdsson, Sigurdur and Slagboom, P Eline and Stott, David J M and van Swieten, John C and Teumer, Alexander and T{\"o}glhofer, Anna Maria and Traylor, Matthew and Trompet, Stella and Turner, Stephen T and Tzourio, Christophe and Uh, Hae-Won and Uitterlinden, Andr{\'e} G and Vernooij, Meike W and Wang, Jing J and Wong, Tien Y and Wardlaw, Joanna M and Windham, B Gwen and Wittfeld, Katharina and Wolf, Christiane and Wright, Clinton B and Yang, Qiong and Zhao, Wei and Zijdenbos, Alex and Jukema, J Wouter and Sacco, Ralph L and Kardia, Sharon L R and Amouyel, Philippe and Mosley, Thomas H and Longstreth, W T and DeCarli, Charles C and van Duijn, Cornelia M and Schmidt, Reinhold and Launer, Lenore J and Grabe, Hans J and Seshadri, Sudha S and Ikram, M Arfan and Fornage, Myriam} }