James F Meschia

University of Alabama at Birmingham, Birmingham, Alabama, United States

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Publications (282)2206.2 Total impact

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    ABSTRACT: Background: The value of neuron-specific enolase (NSE) in predicting clinical outcomes has been investigated in a variety of neurological disorders. Objective: To investigate the associations of serum NSE with severity of bleeding and functional outcomes in patients with subarachnoid hemorrhage (SAH). Methods: We retrospectively reviewed the records of patients with SAH from June 2008 to June 2012. The severity of SAH bleeding at admission was measured radiographically with the Fisher scale and clinically with the Glasgow Coma Scale, Hunt and Hess grade, and World Federation of Neurologic Surgeons scale. Outcomes were assessed with the modified Rankin Scale at discharge. Results: We identified 309 patients with nontraumatic SAH, and 71 had NSE testing. Median age was 54 years (range, 23-87 years), and 44% were male. In multivariable analysis, increased NSE was associated with a poorer Hunt and Hess grade (P = .003), World Federation of Neurologic Surgeons scale score (P < .001), and Glasgow Coma Scale score (P = .003) and worse outcomes (modified Rankin Scale at discharge; P = .001). There was no significant association between NSE level and Fisher grade (P = .81) in multivariable analysis. Conclusion: We found a significant association between higher NSE levels and poorer clinical presentations and worse outcomes. Although it is still early for any relevant clinical conclusions, our results suggest that NSE holds promise as a tool for screening patients at increased risk of poor outcomes after SAH. Abbreviations: BMI, body mass indexGCS, Glasgow Coma ScalemRS, modified Rankin ScaleNSE, neuron-specific enolaseSAH, subarachnoid hemorrhageWFNS, World Federation of Neurologic Surgeons.
    Neurosurgery 11/2015; DOI:10.1227/NEU.0000000000001140 · 3.62 Impact Factor
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    ABSTRACT: Background and purpose: Prior meta-analysis showed that carotid endarterectomy benefits decline with increasing surgical delay following symptoms. For symptomatic patients in the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST), we assessed if differences in time between symptoms and carotid endarterectomy or carotid artery stenting are associated with differences in risk of periprocedural stroke or death. Methods: We analyzed the 1180 symptomatic patients in CREST who received their assigned procedure and had clearly defined timing of symptoms. Patients were classified into 3 groups based on time from symptoms to procedure: <15, 15 to 60, and >60 days. Results: For carotid endarterectomy, risk of periprocedural stroke or death was not significantly different for the 2 later time periods relative to the earliest time period (hazard ratio, 0.74; 95% confidence interval, 0.22-2.49 for 15-60 days and hazard ratio, 0.91; 95% confidence interval, 0.25-3.33 for >60 days; P=0.89). For carotid artery stenting, risk of periprocedural stroke or death was also not significantly different for later time periods relative to the earliest time period (hazard ratio, 1.12; 95% confidence interval, 0.53-2.40 for 15-60 days and hazard ratio, 1.15; 95% confidence interval, 0.48-2.75 for >60 days; P=0.93). Conclusions: Time from symptoms to carotid endarterectomy or carotid artery stenting did not alter periprocedural safety, supporting early revascularization regardless of modality. Clinical trial registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00004732.
    Stroke 10/2015; DOI:10.1161/STROKEAHA.115.011123 · 5.72 Impact Factor
  • Kevin M Barrett · Brajesh K Lal · James F Meschia ·
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    ABSTRACT: Evidence-based therapeutic options for stroke continue to emerge based on results from well-designed clinical studies. Ischemic stroke far exceeds hemorrhagic stroke in terms of prevalence and incidence, both in the USA and worldwide. The public health effect of reducing death and disability related to ischemic stroke justifies the resources that have been invested in identifying safe and effective treatments. The emergence of novel oral anticoagulants for ischemic stroke prevention in atrial fibrillation has introduced complexity to clinical decision making for patients with this common cardiac arrhythmia. Some accepted ischemic stroke preventative strategies, such as carotid revascularization for asymptomatic carotid stenosis, require reassessment, given advances in risk factor management, antithrombotic therapy, and surgical techniques. Intra-arterial therapy, particularly with stent retrievers after intravenous tissue plasminogen activator, has recently been demonstrated to improve functional outcomes and will require investment in system-based care models to ensure that effective treatments are received by patients in a timely fashion. The purpose of this review is to describe recent advances in medical and surgical approaches to ischemic stroke prevention and acute treatment. Results from recently published clinical trials will be highlighted along with ongoing clinical trials addressing key questions in ischemic stroke management and prevention where equipoise remains.
    Current Cardiology Reports 10/2015; 17(10):637. DOI:10.1007/s11886-015-0637-1 · 1.93 Impact Factor
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    ABSTRACT: Background and purpose: There is higher combined risk of stroke or death (S+D) at older ages with carotid stenting. We assess whether this can be attributed to patient or arterial characteristics that are in the pathway between older age and higher risk. Methods: Mediation analysis of selected patient (hypertension, diabetes mellitus, and dyslipidemia) and arterial characteristics assessed at the clinical sites and the core laboratory (plaque length, eccentric plaque, ulcerated plaque, percent stenosis, peak systolic velocity, and location) was performed in 1123 carotid artery stenting-treated patients in the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST). We assessed the association of age with these characteristics, the association of these characteristics with stroke risk, and the amount of mediation of the association of age on the combined risk of periprocedural S+D with adjustment for these factors. Results: Only plaque length as measured at the sites increased with age, was associated with increased S+D risk and significantly mediated the association of age on S+D risk. However, adjustment for plaque length attenuated the increased risk per 10 years of age from 1.72 (95% confidence interval, 1.26-2.37) to 1.66 (95% confidence interval, 1.20-2.29), accounting for only 8% of the increased risk. Conclusions: Plaque length seems to be in the pathway between older age and higher risk of S+D among carotid artery stenting-treated patients, but it mediated only 8% of the age effect excess risk of carotid artery stenting in CREST. Other factors and mechanisms underlying the age effect need to be identified as plaque length will not identify elderly patients for whom stenting is safe relative to endarterectomy. Clinical trial registration: URL: http://clinicaltrials.gov. Unique Identifier: NCT00004732.
    Stroke 09/2015; 46(10). DOI:10.1161/STROKEAHA.115.009516 · 5.72 Impact Factor
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    ABSTRACT: 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. 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). Heritabilities for young-onset stroke and old-onset stroke were estimated at 42% (±8%, P < 0.001) and 34% (±10%, P < 0.001), respectively. 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. © 2015 EAN.
    European Journal of Neurology 09/2015; 22(11). DOI:10.1111/ene.12827 · 4.06 Impact Factor
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    ABSTRACT: The association between resting heart rate and ischemic stroke remains unclear. To examine the association between resting heart rate and ischemic stroke. A total of 24 730 participants (mean age: 64 ± 9·3 years; 59% women; 41% blacks) from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study who were free of stroke at the time of enrollment (2003-2007) were included in this analysis. Resting heart rate was determined from baseline electrocardiogram data. Heart rate was examined as a continuous variable per 10 bpm increase and also as a categorical variable using tertiles ( <61 bpm, 61 to 70 bpm, and >70 bpm). First-time ischemic stroke events were identified during follow-up and adjudicated by physician review. Over a median follow-up of 7·6 years, a total of 646 ischemic strokes occurred. In a Cox regression model adjusted for socio-demographics, cardiovascular risk factors, and potential confounders, each 10 bpm increase in heart rate was associated with a 10% increase in the risk of ischemic stroke (hazard ratio = 1·10, 95% confidence interval = 1·02, 1·18). In the categorical model, an increased risk of ischemic stroke was observed for heart rates in the middle (hazard ratio = 1·29, 95% confidence interval = 1·06, 1·57) and upper (hazard ratio = 1·37, 95% confidence interval = 1·12, 1·67) tertiles compared with the lower tertile. The results were consistent when the analysis was stratified by age, gender, race, exercise habits, hypertension, and coronary heart disease. In REGARDS, high resting heart rates were associated with an increased risk of ischemic stroke compared with low heart rates. Further research is needed to examine whether interventions aimed to reduce heart rate decrease stroke risk. © 2015 World Stroke Organization.
    International Journal of Stroke 08/2015; DOI:10.1111/ijs.12620 · 3.83 Impact Factor
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    ABSTRACT: Post-hoc, we hypothesized that over the recruitment period of the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST), increasing experience and improved patient selection with carotid stenting, and to a lesser extent, carotid endarterectomy would contribute to lower periprocedural event rates. Three study periods with approximately the same number of patients were defined to span recruitment. Composite and individual rates of periprocedural stroke, myocardial infarction, and death rate were calculated separately by treatment assignment (carotid stenting/carotid endarterectomy). Temporal changes in unadjusted event rates, and rates after adjustment for temporal changes in patient characteristics, were assessed. For patients randomized to carotid stenting, there was no significant temporal change in the unadjusted composite rates that declined from 6.2% in the first period, to 4.9% in the second, and 4.6% in the third (P=0.28). Adjustment for patient characteristics attenuated the rates to 6.0%, 5.9%, and 5.6% (P=0.85). For carotid endarterectomy-randomized patients, both the composite and the combined stroke and death outcome decreased between periods 1 and 2 and then increased in period 3. The hypothesized temporal reduction of stroke+death events for carotid stenting-treated patients was not observed. Further adjustment for changes in patient characteristics between periods, including the addition of asymptomatic patients and a >50% decrease in proportion of octogenarians enrolled, resulted in practically identical rates. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00004732. © 2015 American Heart Association, Inc.
    Stroke 07/2015; 46(8). DOI:10.1161/STROKEAHA.115.008898 · 5.72 Impact Factor
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    ABSTRACT: The aim of this guideline is to provide a focused update of the current recommendations for the endovascular treatment of acute ischemic stroke. Where there is overlap, the recommendations made here supersede those of previous guidelines. This focused update analyzes results from 8 randomized clinical trials of endovascular treatment and other relevant data published since 2013. It is not intended to be a complete literature review from the date of the previous guideline publication but rather to include pivotal new evidence that justifies changes in current recommendations. Members of the writing committee were appointed by the American Heart Association/American Stroke Association Stroke Council's Scientific Statement Oversight Committee and the American Heart Association/American Stroke Association Manuscript Oversight Committee (MOC). Strict adherence to the American Heart Association conflict of interest policy was maintained throughout the consensus process. Recommendations follow the American Heart Association/American Stroke Association methods of classifying the level of certainty of the treatment effect and the class of evidence. Prerelease review of the draft guideline was performed by 6 expert peer reviewers and by the members of the Stroke Council Scientific Statement Oversight Committee and Stroke Council Leadership Committee. Evidence-based guidelines are presented for the selection of patients with acute ischemic stroke for endovascular treatment, the endovascular procedure and for systems of care to facilitate endovascular treatment. Certain endovascular procedures have been demonstrated to provide clinical benefit in selected patients with acute ischemic stroke. Systems of care should be organized to facilitate the delivery of this care. © 2015 American Heart Association, Inc.
    Stroke 06/2015; 46(10). DOI:10.1161/STR.0000000000000074 · 5.72 Impact Factor
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    ABSTRACT: Intracerebral hemorrhage has a substantial genetic component. We performed a preliminary search for rare coding variants associated with intracerebral hemorrhage. A total of 757 cases and 795 controls were genotyped using the Illumina HumanExome Beadchip (Illumina, Inc, San Diego, CA). Meta-analyses of single-variant and gene-based association were computed. No rare coding variants were associated with intracerebral hemorrhage. Three common variants on chromosome 19q13 at an established susceptibility locus, encompassing TOMM40, APOE, and APOC1, met genome-wide significance (P<5e-08). After adjusting for the APOE epsilon alleles, this locus was no longer convincingly associated with intracerebral hemorrhage. No gene reached genome-wide significance level in gene-based association testing. Although no coding variants of large effect were detected, this study further underscores a major challenge for the study of genetic susceptibility loci; large sample sizes are required for sufficient power except for loci with large effects. © 2015 American Heart Association, Inc.
    Stroke 06/2015; 46(8). DOI:10.1161/STROKEAHA.115.009838 · 5.72 Impact Factor
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    ABSTRACT: 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. 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. The 15q21.3 locus linked with lipid levels and hypertension was associated with total stroke (rs4471613; P=3.9×10(-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. 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. © 2015 American Heart Association, Inc.
    Stroke 06/2015; 46(8). DOI:10.1161/STROKEAHA.115.009044 · 5.72 Impact Factor
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    ABSTRACT: Spontaneous intracranial artery dissection is an uncommon and probably underdiagnosed cause of stroke that is defined by the occurrence of a haematoma in the wall of an intracranial artery. Patients can present with headache, ischaemic stroke, subarachnoid haemorrhage, or symptoms associated with mass effect, mostly on the brainstem. Although intracranial artery dissection is less common than cervical artery dissection in adults of European ethnic origin, intracranial artery dissection is reportedly more common in children and in Asian populations. Risk factors and mechanisms are poorly understood, and diagnosis is challenging because characteristic imaging features can be difficult to detect in view of the small size of intracranial arteries. Therefore, multimodal follow-up imaging is often needed to confi rm the diagnosis. Treatment of intracranial artery dissections is empirical in the absence of data from randomised controlled trials. Most patients with subarachnoid haemorrhage undergo surgical or endovascular treatment to prevent rebleeding, whereas patients with intracranial artery dissection and cerebral ischaemia are treated with antithrombotics. Prognosis seems worse in patients with subarachnoid haemorrhage than in those without.
    The Lancet Neurology 06/2015; 14(6):640-654. DOI:10.1016/S1474-4422(15)00009-5 · 21.90 Impact Factor
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    ABSTRACT: Stroke is the second leading cause of death and the third leading cause of years of life lost. Genetic factors contribute to stroke prevalence, and candidate gene and genome-wide association studies (GWAS) have identified variants associated with ischemic stroke risk. These variants often have small effects without obvious biological significance. Exome sequencing may discover predicted protein-altering variants with a potentially large effect on ischemic stroke risk. To investigate the contribution of rare and common genetic variants to ischemic stroke risk by targeting the protein-coding regions of the human genome. The National Heart, Lung, and Blood Institute (NHLBI) Exome Sequencing Project (ESP) analyzed approximately 6000 participants from numerous cohorts of European and African ancestry. For discovery, 365 cases of ischemic stroke (small-vessel and large-vessel subtypes) and 809 European ancestry controls were sequenced; for replication, 47 affected sibpairs concordant for stroke subtype and an African American case-control series were sequenced, with 1672 cases and 4509 European ancestry controls genotyped. The ESP's exome sequencing and genotyping started on January 1, 2010, and continued through June 30, 2012. Analyses were conducted on the full data set between July 12, 2012, and July 13, 2013. Discovery of new variants or genes contributing to ischemic stroke risk and subtype (primary analysis) and determination of support for protein-coding variants contributing to risk in previously published candidate genes (secondary analysis). We identified 2 novel genes associated with an increased risk of ischemic stroke: a protein-coding variant in PDE4DIP (rs1778155; odds ratio, 2.15; P = 2.63 × 10-8) with an intracellular signal transduction mechanism and in ACOT4 (rs35724886; odds ratio, 2.04; P = 1.24 × 10-7) with a fatty acid metabolism; confirmation of PDE4DIP was observed in affected sibpair families with large-vessel stroke subtype and in African Americans. Replication of protein-coding variants in candidate genes was observed for 2 previously reported GWAS associations: ZFHX3 (cardioembolic stroke) and ABCA1 (large-vessel stroke). Exome sequencing discovered 2 novel genes and mechanisms, PDE4DIP and ACOT4, associated with increased risk for ischemic stroke. In addition, ZFHX3 and ABCA1 were discovered to have protein-coding variants associated with ischemic stroke. These results suggest that genetic variation in novel pathways contributes to ischemic stroke risk and serves as a target for prediction, prevention, and therapy.
    05/2015; 72(7). DOI:10.1001/jamaneurol.2015.0582
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    ABSTRACT: The most common monogenic cause of cerebral small-vessel disease is cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, caused by NOTCH3 gene mutations. It has been hypothesized that more common variants in NOTCH3 may also contribute to the risk of sporadic small-vessel disease. Previously, 4 common variants (rs10404382, rs1043994, rs10423702, and rs1043997) were found to be associated with the presence of white matter hyperintensity in hypertensive community-dwelling elderly. We investigated the association of common single nucleotide polymorphisms (SNPs) in NOTCH3 in 1350 patients with MRI-confirmed lacunar stroke and 7397 controls, by meta-analysis of genome-wide association study data sets. In addition, we investigated the association of common SNPs in NOTCH3 with MRI white matter hyperintensity volumes in 3670 white patients with ischemic stroke. In each analysis, we considered all SNPs within the NOTCH3 gene, and within 50-kb upstream and downstream of the coding region. A total of 381 SNPs from the 1000 genome population with a mean allele frequency >0.01 were included in the analysis. A significance level of P<0.0015 was used, adjusted for the effective number of independent SNPs in the region using the Galwey method. We found no association of any common variants in NOTCH3 (including rs10404382, rs1043994, rs10423702, and rs1043997) with lacunar stroke or white matter hyperintensity volume. We repeated our analysis stratified for hypertension but again found no association. Our study does not support a role for common NOTCH3 variation in the risk of sporadic small-vessel disease. © 2015 The Authors.
    Stroke 05/2015; 46(6). DOI:10.1161/STROKEAHA.114.008540 · 5.72 Impact Factor
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    ABSTRACT: Background and Purpose—Although pharmacological treatment of hypertension has important health benefits, it does not capture the benefit of maintenance of ideal health through the prevention or delay of hypertension. Methods—A total of 26 875 black and white participants aged 45+ years were assessed and followed for incident stroke events. The association was assessed between incident stroke and: (1) systolic blood pressure (SBP)categorized as normal (<120 mm Hg), prehypertension (120–139 mm Hg), stage 1 hypertension (140–159 mm Hg), and stage 2 hypertension (160 mm Hg+), and (2) number of classes of antihypertensive medications, classified as none, 1, 2, or 3 or more. Results—During 6.3 years of follow-up, 823 stroke events occurred. Nearly half (46%) of the population were successfully treated (SBP<140 mm Hg) hypertensives. Within blood pressure strata, the risk of stroke increased with each additional class of required antihypertensive medication, with hazard ratio [HR], 1.33; 95% confidence interval, 1.16 to 1.52 for normotensive, HR, 1.15; 95% confidence interval, 1.05 to 1.26 for prehypertension, and HR, 1.22; 95% confidence interval, 1.06 to 1.39 for stage 1 hypertension. A successfully treated (SBP<120 mm Hg) hypertensive person on 3+ antihypertensive medication classes was at marginally higher stroke risk than a person with untreated stage 1 hypertension (HR, 2.48 versus HR=2.19; relative to those with SBP <120 on no antihypertensive medications). Conclusions—Maintaining the normotensive status solely through pharmacological treatment has a profound impact, as nearly half of this general population cohort were treated to guideline (SBP<140 mm Hg) but failed to return to risk levels similar to normotensive individuals. Even with successful treatment, there is a substantial potential gain by prevention or delay of hypertension.
    Stroke 05/2015; 46(6). DOI:10.1161/STROKEAHA.115.009128 · 5.72 Impact Factor
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    ABSTRACT: Objective: To quantify genetic overlap between migraine and ischemic stroke (IS) with respect to common genetic variation. Methods: We applied 4 different approaches to large-scale meta-analyses of genome-wide data on migraine (23,285 cases and 95,425 controls) and IS (12,389 cases and 62,004 controls). First, we queried known genome-wide significant loci for both disorders, looking for potential overlap of signals. We then analyzed the overall shared genetic load using polygenic scores and estimated the genetic correlation between disease subtypes using data derived from these models. We further interrogated genomic regions of shared risk using analysis of covariance patterns between the 2 phenotypes using cross-phenotype spatial mapping. Results: We found substantial genetic overlap between migraine and IS using all 4 approaches. Migraine without aura (MO) showed much stronger overlap with IS and its subtypes than migraine with aura (MA). The strongest overlap existed between MO and large artery stroke (LAS; p = 6.4 × 10(-28) for the LAS polygenic score in MO) and between MO and cardioembolic stroke (CE; p = 2.7 × 10(-20) for the CE score in MO). Conclusions: Our findings indicate shared genetic susceptibility to migraine and IS, with a particularly strong overlap between MO and both LAS and CE pointing towards shared mechanisms. Our observations on MA are consistent with a limited role of common genetic variants in this subtype.
    Neurology 05/2015; 84(21). DOI:10.1212/WNL.0000000000001606 · 8.29 Impact Factor
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    ABSTRACT: Background and purposeLow density lipoprotein receptor related proteins (LRPs) 1 and 6 have been implicated in cerebral ischaemia. In addition, genetic variation in LRP1 and LRP6 has been linked with various factors that are related to risk of ischaemic stroke. The aim of this study was to examine the association of LRP1 and LRP6 gene variants with risk of ischaemic stroke as part of the Ischemic Stroke Genetics Study (ISGS).MethodsA Caucasian series (434 stroke patients, 319 controls) and an African American series (161 stroke patients, 116 controls) were included. Fourteen LRP6 variants and three LRP1 variants were genotyped and assessed for association with ischaemic stroke.ResultsIn the Caucasian series, significant associations with ischaemic stroke were observed for LRP6 rs2075241 [odds ratio (OR) 0.42, P = 0.023], rs2302685 (OR 0.44, P = 0.049), rs7975614 (OR 0.07, P = 0.017), rs10492120 (OR 0.62, P = 0.036) and rs10743980 (OR 0.66, P = 0.037). Risk of ischaemic stroke was significantly lower for carriers of any of these five protective LRP6 variants (24.0% of subjects) compared to non-carriers (OR 0.57, P = 0.003). The protective association for LRP6 rs2075241 was observed at a similar magnitude across ischaemic stroke subtypes, whilst the effects of rs23022685, rs10492120 and rs10743980 were most apparent for cardioembolic and large vessel stroke. In the African American series, LRP1 rs11172113 was associated with an increased risk of stroke (OR 1.89, P = 0.006).Conclusions The results of our preliminary study provide evidence that LRP6 and LRP1 variants may be associated with risk of ischaemic stroke. Validation in larger studies is warranted.
    European Journal of Neurology 05/2015; 22(8). DOI:10.1111/ene.12735 · 4.06 Impact Factor
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    ABSTRACT: White matter hyperintensities (WMH) are a common radiographic finding and may be a useful endophenotype for small vessel diseases. Given high heritability of WMH, we hypothesised that certain genotypes may predispose individuals to these lesions and consequently, to an increased risk of stroke, dementia and death. We performed a meta-analysis of studies investigating candidate genes and WMH to elucidate the genetic susceptibility to WMH and tested associated variants in a new independent WMH cohort. We assessed a causal relationship of WMH to methylene tetrahydrofolate reductase (MTHFR). Database searches through March 2014 were undertaken and studies investigating candidate genes in WMH were assessed. Associated variants were tested in a new independent ischaemic cohort of 1202 WMH patients. Mendelian randomization was undertaken to assess a causal relationship between WMH and MTHFR. We identified 43 case-control studies interrogating eight polymorphisms in seven genes covering 6,314 WMH cases and 15,461 controls. Fixed-effects meta-analysis found that the C-allele containing genotypes of the aldosterone synthase CYP11B2 T(-344)C gene polymorphism were associated with a decreased risk of WMH (OR=0.61; 95% CI, 0.44 to 0.84; p=0.003). Using mendelian randomisation the association among MTHFR C677T, homocysteine levels and WMH, approached, but did not reach, significance (expected OR=1.75; 95% CI, 0.90-3.41; observed OR=1.68; 95% CI, 0.97-2.94). Neither CYP11B2 T(-344)C nor MTHFR C677T were significantly associated when tested in a new independent cohort of 1202 patients with WMH. There is a genetic basis to WMH but anonymous genome wide and exome studies are more likely to provide novel loci of interest. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
    Journal of neurology, neurosurgery, and psychiatry 04/2015; DOI:10.1136/jnnp-2014-309685 · 6.81 Impact Factor
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    ABSTRACT: We hypothesized that common variants in the collagen genes COL4A1/COL4A2 are associated with sporadic forms of cerebral small vessel disease. We conducted meta-analyses of existing genotype data among individuals of European ancestry to determine associations of 1,070 common single nucleotide polymorphisms (SNPs) in the COL4A1/COL4A2 genomic region with the following: intracerebral hemorrhage and its subtypes (deep, lobar) (1,545 cases, 1,485 controls); ischemic stroke and its subtypes (cardioembolic, large vessel disease, lacunar) (12,389 cases, 62,004 controls); and white matter hyperintensities (2,733 individuals with ischemic stroke and 9,361 from population-based cohorts with brain MRI data). We calculated a statistical significance threshold that accounted for multiple testing and linkage disequilibrium between SNPs (p < 0.000084). Three intronic SNPs in COL4A2 were significantly associated with deep intracerebral hemorrhage (lead SNP odds ratio [OR] 1.29, 95% confidence interval [CI] 1.14-1.46, p = 0.00003; r(2) > 0.9 between SNPs). Although SNPs associated with deep intracerebral hemorrhage did not reach our significance threshold for association with lacunar ischemic stroke (lead SNP OR 1.10, 95% CI 1.03-1.18, p = 0.0073), and with white matter hyperintensity volume in symptomatic ischemic stroke patients (lead SNP OR 1.07, 95% CI 1.01-1.13, p = 0.016), the direction of association was the same. There was no convincing evidence of association with white matter hyperintensities in population-based studies or with non-small vessel disease cerebrovascular phenotypes. Our results indicate an association between common variation in the COL4A2 gene and symptomatic small vessel disease, particularly deep intracerebral hemorrhage. These findings merit replication studies, including in ethnic groups of non-European ancestry. © 2015 American Academy of Neurology.
    Neurology 02/2015; 84(9). DOI:10.1212/WNL.0000000000001309 · 8.29 Impact Factor
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    ABSTRACT: 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. 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. High genetic correlation was identified between LAA and SVD using linear mixed models (rg=0.96, SE=0.47, P=9×10(-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=1×10(-7)) for single nucleotide polymorphisms near the opioid receptor μ1 (OPRM1) gene. 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. © 2015 American Heart Association, Inc.
    Stroke 01/2015; 46(3). DOI:10.1161/STROKEAHA.114.007930 · 5.72 Impact Factor
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    ABSTRACT: Epidemiological studies suggest that white matter hyperintensities (WMH) are extremely heritable, but the underlying genetic variants are largely unknown. Pathophysiological heterogeneity is known to reduce the power of genome-wide association studies (GWAS). Hypertensive and nonhypertensive individuals with WMH might have different underlying pathologies. We used GWAS data to calculate the variance in WMH volume (WMHV) explained by common single nucleotide polymorphisms (SNPs) as a measure of heritability (SNP heritability [HSNP]) and tested the hypothesis that WMH heritability differs between hypertensive and nonhypertensive individuals. WMHV was measured on MRI in the stroke-free cerebral hemisphere of 2336 ischemic stroke cases with GWAS data. After adjustment for age and intracranial volume, we determined which cardiovascular risk factors were independent predictors of WMHV. Using the genome-wide complex trait analysis tool to estimate HSNP for WMHV overall and within subgroups stratified by risk factors found to be significant in multivariate analyses. A significant proportion of the variance of WMHV was attributable to common SNPs after adjustment for significant risk factors (HSNP=0.23; P=0.0026). HSNP estimates were higher among hypertensive individuals (HSNP=0.45; P=7.99×10(-5)); this increase was greater than expected by chance (P=0.012). In contrast, estimates were lower, and nonsignificant, in nonhypertensive individuals (HSNP=0.13; P=0.13). A quarter of variance is attributable to common SNPs, but this estimate was greater in hypertensive individuals. These findings suggest that the genetic architecture of WMH in ischemic stroke differs between hypertensives and nonhypertensives. Future WMHV GWAS studies may gain power by accounting for this interaction. © 2014 The Authors. Published on behalf of the American Heart Association, Inc., by Wolters Kluwer.
    Stroke 12/2014; 46(2). DOI:10.1161/STROKEAHA.114.006849 · 5.72 Impact Factor

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7k Citations
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  • 2014
    • University of Alabama at Birmingham
      • School of Public Health
      Birmingham, Alabama, United States
  • 2013
    • University of Newcastle
      • School of Nursing and Midwifery
      Newcastle, New South Wales, Australia
    • University of Mississippi
      Mississippi, United States
    • Imperial College London
      Londinium, England, United Kingdom
  • 2000-2013
    • Mayo Foundation for Medical Education and Research
      • • Department of Neurology
      • • Department of Pharmacology
      • • Mayo Medical School
      Рочестер, Michigan, United States
  • 2012
    • University of Oxford
      • Wellcome Trust Centre for Human Genetics
      Oxford, ENG, United Kingdom
    • St George's, University of London
      • Stroke and Dementia Research Centre
      Londinium, England, United Kingdom
  • 2011
    • University College London
      • Department of Epidemiology and Public Health
      London, ENG, United Kingdom
  • 2005-2010
    • Mayo Clinic
      Jacksonville, Florida, United States
  • 2004-2010
    • University of Florida
      Gainesville, Florida, United States
    • Coriell Institute for Medical Research
      Camden, New Jersey, United States
  • 2004-2009
    • University of Cincinnati
      • Department of Neurology
      Cincinnati, Ohio, United States
  • 2008
    • University of Innsbruck
      Innsbruck, Tyrol, Austria
  • 2004-2008
    • Mayo Clinic - Rochester
      • Department of Neurology
      Rochester, MN, United States
  • 2007
    • Icahn School of Medicine at Mount Sinai
      Manhattan, New York, United States
    • Massachusetts General Hospital
      Boston, Massachusetts, United States
  • 2004-2007
    • Emory University
      • Department of Neurology
      Atlanta, Georgia, United States
  • 1997-2002
    • Indiana University-Purdue University Indianapolis
      • Department of Neurology
      Indianapolis, Indiana, United States
  • 2001
    • University of Virginia
      Charlottesville, Virginia, United States