| 1. |
- Björck, Hanna M., et al.
(author)
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Characterization of Shear-Sensitive Genes in the NormalRat Aorta Identifies Hand2 as a Major Flow-ResponsiveTranscription Factor
- 2012
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:12
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Journal article (peer-reviewed)abstract
- Objective: Shear forces play a key role in the maintenance of vessel wall integrity. Current understanding regarding shear-dependent gene expression is mainly based on in vitro or in vivo observations with experimentally deranged shear, hence reflecting acute molecular events in relation to flow. Our objective was to determine wall shear stress (WSS) in the rat aorta and study flow-dependent vessel wall biology under physiological conditions.Methods and Results: Animal-specific aortic WSS magnitude and vector direction were estimated using computational fluid dynamic simulation based on aortic geometry and flow information acquired by MRI. Two distinct flow pattern regions were identified in the normal rat aorta; the distal part of the inner curvature being exposed to low WSS and a non-uniform vector direction, and a region along the outer curvature being subjected to markedly higher levels of WSS and a uniform vector direction. Microarray analysis revealed a strong differential expression between the flow regions, particularly associated with transcriptional regulation. In particular, several genes related to Ca2+-signalling, inflammation, proliferation and oxidative stress were among the most highly differentially expressed.Conclusions: Microarray analysis validated the CFD-defined WSS regions in the rat aorta, and several novel flow-dependent genes were identified. The importance of these genes in relation to atherosusceptibility needs further investigation.
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| 2. |
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| 3. |
- Folkersen, Lasse, et al.
(author)
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Association of genetic risk variants with expression of proximal genes identifies novel susceptibility genes for cardiovascular disease
- 2010
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In: Circulation. - 1942-325X .- 1942-3268. ; 3:4, s. 365-373
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Journal article (peer-reviewed)abstract
- BACKGROUND: Population-based genome-wide association studies have identified several single nucleotide polymorphisms (SNPs) associated with cardiovascular disease or its risk factors. Genes in close proximity to these risk-SNPs are often thought to be pathogenetically important based on their location alone. However, the actual connections between SNPs and disease mechanisms remain largely unknown. METHODS AND RESULTS: To identify novel susceptibility genes, we investigated how 166 SNPs previously found to be associated with increased cardiovascular risk and/or predisposing metabolic traits relate to the expression of nearby genes. Gene expression in 577 samples of aorta, liver, mammary artery, and carotid atherosclerotic plaque was measured using expression arrays. For 47 SNPs, the expression levels of proximal genes (located within 200 kb) were affected (P<0.005). More than 20 of these genes had not previously been identified as candidate genes for cardiovascular or related metabolic traits. SNP-associated gene effects were tissue-specific and the tissue specificity was phenotype-dependent. CONCLUSIONS: This study demonstrates several instances of association between risk-SNPs and genes immediately adjacent to them. It also demonstrates instances in which the associated gene is not the immediately proximal and obvious candidate gene for disease. This shows the necessity of careful studies of genetic marker data as a first step toward application of genome-wide association studies findings in a clinical setting.
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| 4. |
- Folkersen, Lasse
(author)
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Phenotype and genotype effects on the transcriptome in cardiovascular disease : tools to identify candidate genes
- 2011
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Doctoral thesis (other academic/artistic)abstract
- The overarching purpose of this thesis was to investigate the expression of human genes and how they relate to cardiovascular disease. This was pursued through five papers, each of which investigated different aspects of gene expression. Paper I improved the technology for extracting gene expression information from microarrays. Its main purpose was to introduce the software package GeneRegionScan, which was developed for analysis of genomic regions with inaccurate annotation. Paper II explored the genomic region surrounding the first identified single‐ nucleotide polymorphism (SNP) associated with cardiovascular disease. The purpose of the paper was to investigate transcript isoforms of the regional genes and their association to the risk‐SNPs in the region. Eight new transcript isoforms were introduced, but no pattern of association with genotype was observed. Paper III extended the methods of paper II, by expanding the search to 166 risk‐ SNPs known at the time. For each of these SNPs, it was hypothesized that one or more proximal genes had expression levels that were associated to the genotype of the SNP in question. It was reported that 47 of the SNPs had such genes, thus progressing from risk‐SNPs towards risk‐genes. In addition the paper introduced new concepts on distance between gene and risk SNP and on the tissue‐ specificity of associations. Paper IV investigated the gene expression pattern of thoracic aortic aneurysm. It had previously been observed that patients with congenital bicuspid aortic valve (BAV) had increased severity and earlier onset age of aneurysm, when compared to patients with the normal tricuspid aortic valve (TAV). A fundamentally differing gene expression profile was observed between these two patient groups, and a possible immunological involvement in TAV patients was reported. Paper V asked if the high‐throughput methods of genomics and transcriptomics could be applied towards better prediction of future ischemic events in patients with established atherosclerosis. Risk‐SNP profiles, gene expression profiles of circulating blood cells, and gene expression profiles of carotid plaque samples were utilized. Particularly gene expression profiles of carotid plaque provided improved prediction above that of the established risk markers of serum lipids, gender, age and smoking.
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| 5. |
- Folkersen, Lasse, et al.
(author)
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Unraveling Divergent Gene Expression Profiles in Bicuspid and Tricuspid Aortic Valve Patients with Thoracic Aortic Dilatation: The ASAP Study
- 2011
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In: Molecular Medicine. - : Feinstein Institute for Medical Research. - 1076-1551 .- 1528-3658. ; 17:11-12, s. 1365-1373
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Journal article (peer-reviewed)abstract
- Thoracic aortic aneurysm (TAA) is a common complication in patients with a bicuspid aortic valve (BAV), the most frequent congenital heart disorder. For unknown reasons TAA occurs at a younger age, with a higher frequency in BAV patients than in patients with a tricuspid aortic valve (TAV), resulting in an increased risk for aortic dissection and rupture. To investigate the increased TAA incidence in BAV patients, we obtained tissue biopsy samples from nondilated and dilated aortas of 131 BAV and TAV patients. Global gene expression profiles were analyzed from controls and from aortic intima-media and adventitia of patients (in total 345 samples). Of the genes found to be differentially expressed with dilation, only a few (less than4%) were differentially expressed in both BAV and TAV patients. With the use of gene set enrichment analysis, the cell adhesion and extracellular region gene ontology sets were identified as common features of TAA in both BAV and TAV patients. Immune response genes were observed to be particularly overexpressed in the aortic media of dilated TAV samples. The divergent gene expression profiles indicate that there are fundamental differences in TAA etiology in BAV and TAV patients. Immune response activation solely in the aortic media of TAV patients suggests that inflammation is involved in TAA formation in TAV but not in BAV patients. Conversely, genes were identified that were only differentially expressed with dilation in BAV patients. The result has bearing on future clinical studies in which separate analysis of BAV and TAV patients is recommended.
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| 6. |
- Gertow, Karl, et al.
(author)
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Identification of the BCAR1-CFDP1-TMEM170A Locus as a Determinant of Carotid Intima-Media Thickness and Coronary Artery Disease Risk
- 2012
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In: Circulation: Cardiovascular Genetics. - 1942-325X .- 1942-3268. ; 5:6, s. 656-665
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Journal article (peer-reviewed)abstract
- Background-Carotid intima-media thickness (cIMT) is a widely accepted marker of subclinical atherosclerosis. To date, large-scale investigations of genetic determinants of cIMT are sparse. Methods and Results-To identify cIMT-associated genes and genetic variants, a discovery analysis using the Illumina 200K CardioMetabochip was conducted in 3430 subjects with detailed ultrasonographic determinations of cIMT from the IMPROVE (Carotid Intima Media Thickness [IMT] and IMT-Progression as Predictors of Vascular Events in a High Risk European Population) study. Segment-specific IMT measurements of common carotid, bifurcation, and internal carotid arteries, and composite IMT variables considering the whole carotid tree (IMTmean, IMTmax, and IMTmean-max), were analyzed. A replication stage investigating 42 single-nucleotide polymorphisms for association with common carotid IMT was undertaken in 5 independent European cohorts (total n=11 590). A locus on chromosome 16 (lead single-nucleotide polymorphism rs4888378, intronic in CFDP1) was associated with cIMT at significance levels passing multiple testing correction at both stages (array-wide significant discovery P=6.75x10(-7) for IMTmax; replication P=7.24x10(-6) for common cIMT; adjustments for sex, age, and population substructure where applicable; minor allele frequency 0.43 and 0.41, respectively). The protective minor allele was associated with lower carotid plaque score in a replication cohort (P=0.04, n=2120) and lower coronary artery disease risk in 2 case-control studies of subjects with European ancestry (odds ratio [95% confidence interval] 0.83 [0.77-0.90], P=6.53x10(-6), n=13 591; and 0.95 [0.92-0.98], P=1.83x10(-4), n= 82 297, respectively). Queries of human biobank data sets revealed associations of rs4888378 with nearby gene expression in vascular tissues (n=126-138). Conclusions-This study identified rs4888378 in the BCAR1-CFDP1-TMEM170A locus as a novel genetic determinant of cIMT and coronary artery disease risk in individuals of European descent. (Circ Cardiovasc Genet. 2012;5:656-665.)
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| 7. |
- Gretarsdottir, Solveig, et al.
(author)
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Genome-wide association study identifies a sequence variant within the DAB2IP gene conferring susceptibility to abdominal aortic aneurysm
- 2010
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In: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 42:8, s. 71-692
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Journal article (peer-reviewed)abstract
- We performed a genome-wide association study on 1,292 individuals with abdominal aortic aneurysms (AAAs) and 30,503 controls from Iceland and The Netherlands, with a follow-up of top markers in up to 3,267 individuals with AAAs and 7,451 controls. The A allele of rs7025486 on 9q33 was found to associate with AAA, with an odds ratio (OR) of 1.21 and P = 4.6 x 10(-10). In tests for association with other vascular diseases, we found that rs7025486[A] is associated with early onset myocardial infarction (OR = 1.18, P = 3.1 x 10(-5)), peripheral arterial disease (OR = 1.14, P = 3.9 x 10(-5)) and pulmonary embolism (OR = 1.20, P = 0.00030), but not with intracranial aneurysm or ischemic stroke. No association was observed between rs7025486[A] and common risk factors for arterial and venous diseases-that is, smoking, lipid levels, obesity, type 2 diabetes and hypertension. Rs7025486 is located within DAB2IP, which encodes an inhibitor of cell growth and survival.
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| 8. |
- Harrison, Seamus C., et al.
(author)
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A gene-centric study of common carotid artery remodelling
- 2013
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In: Atherosclerosis. - : Elsevier BV. - 0021-9150 .- 1879-1484. ; 226:2, s. 440-446
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Journal article (peer-reviewed)abstract
- Background: Expansive remodelling is the process of compensatory arterial enlargement in response to atherosclerotic stimuli. The genetic determinants of this process are poorly characterized. Methods: Genetic association analyses of inter-adventitial common carotid artery diameter (ICCAD) in the IMPROVE study (n = 3427) using the Illumina 200k Metabochip was performed. Single nucleotide polymorphisms (SNPs) that met array-wide significance were taken forward for analysis in three further studies (n = 5704), and tested for association with Abdominal Aortic Aneurysm (AAA). Results: rs3768445 on Chromosome 1q24.3, in a cluster of protein coding genes (DNM3, PIGC, C1orf105) was associated with larger ICCAD in the IMPROVE study. For each copy of the rare allele carried, ICCAD was on average 0.13 mm greater (95% CI 0.08-0.18 mm, P = 8.2 x 10(-8)). A proxy SNP (rs4916251, R-2 = 0.99) did not, however, show association with ICCAD in three follow-up studies (P for replication = 0.29). There was evidence of interaction between carotid intima-media thickness (CIMT) and rs4916251 on ICCAD in two of the cohorts studies suggesting that it plays a role in the remodelling response to atherosclerosis. In meta-analysis of 5 case-control studies pooling data from 5007 cases and 43,630 controls, rs4916251 was associated with presence of AAA 1.10, 95% CI 1.03-1.17, p = 2.8 x 10(-3), I-2 = 18.8, Q = 0.30). A proxy SNP, rs4916251 was also associated with increased expression of PIGC in aortic tissue, suggesting that this may the mechanism by which this locus affects vascular remodelling. Conclusions: Common variation at 1q24.3 is associated with expansive vascular remodelling and risk of AAA. These findings support a hypothesis that pathways involved in systemic vascular remodelling play a role in AAA development.
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| 9. |
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| 10. |
- Holmes, Michael V., et al.
(author)
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Secretory Phospholipase A(2)-IIA and Cardiovascular Disease
- 2013
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In: Journal of the American College of Cardiology. - : Elsevier. - 0735-1097 .- 1558-3597. ; 62:21, s. 1966-1976
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Journal article (peer-reviewed)abstract
- Objectives This study sought to investigate the role of secretory phospholipase A(2) (sPLA(2))-IIA in cardiovascular disease. less thanbrgreater than less thanbrgreater thanBackground Higher circulating levels of sPLA(2)-IIA mass or sPLA(2) enzyme activity have been associated with increased risk of cardiovascular events. However, it is not clear if this association is causal. A recent phase III clinical trial of an sPLA(2) inhibitor (varespladib) was stopped prematurely for lack of efficacy. less thanbrgreater than less thanbrgreater thanMethods We conducted a Mendelian randomization meta-analysis of 19 general population studies (8,021 incident, 7,513 prevalent major vascular events [MVE] in 74,683 individuals) and 10 acute coronary syndrome (ACS) cohorts (2,520 recurrent MVE in 18,355 individuals) using rs11573156, a variant in PLA2G2A encoding the sPLA(2)-IIA isoenzyme, as an instrumental variable. less thanbrgreater than less thanbrgreater thanResults PLA2G2A rs11573156 C allele associated with lower circulating sPLA(2)-IIA mass (38% to 44%) and sPLA(2) enzyme activity (3% to 23%) per C allele. The odds ratio (OR) for MVE per rs11573156 C allele was 1.02 (95% confidence interval [CI]: 0.98 to 1.06) in general populations and 0.96 (95% CI: 0.90 to 1.03) in ACS cohorts. In the general population studies, the OR derived from the genetic instrumental variable analysis for MVE for a 1-log unit lower sPLA(2)-IIA mass was 1.04 (95% CI: 0.96 to 1.13), and differed from the non-genetic observational estimate (OR: 0.69; 95% CI: 0.61 to 0.79). In the ACS cohorts, both the genetic instrumental variable and observational ORs showed a null association with MVE. Instrumental variable analysis failed to show associations between sPLA2 enzyme activity and MVE. less thanbrgreater than less thanbrgreater thanConclusions Reducing sPLA(2)-IIA mass is unlikely to be a useful therapeutic goal for preventing cardiovascular events.
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