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1.  Plasma urate concentration and risk of coronary heart disease: a Mendelian randomisation analysis 
Summary
Background
Increased circulating plasma urate concentration is associated with an increased risk of coronary heart disease, but the extent of any causative effect of urate on risk of coronary heart disease is still unclear. In this study, we aimed to clarify any causal role of urate on coronary heart disease risk using Mendelian randomisation analysis.
Methods
We first did a fixed-effects meta-analysis of the observational association of plasma urate and risk of coronary heart disease. We then used a conventional Mendelian randomisation approach to investigate the causal relevance using a genetic instrument based on 31 urate-associated single nucleotide polymorphisms (SNPs). To account for potential pleiotropic associations of certain SNPs with risk factors other than urate, we additionally did both a multivariable Mendelian randomisation analysis, in which the genetic associations of SNPs with systolic and diastolic blood pressure, HDL cholesterol, and triglycerides were included as covariates, and an Egger Mendelian randomisation (MR-Egger) analysis to estimate a causal effect accounting for unmeasured pleiotropy.
Findings
In the meta-analysis of 17 prospective observational studies (166 486 individuals; 9784 coronary heart disease events) a 1 SD higher urate concentration was associated with an odds ratio (OR) for coronary heart disease of 1·07 (95% CI 1·04–1·10). The corresponding OR estimates from the conventional, multivariable adjusted, and Egger Mendelian randomisation analysis (58 studies; 198 598 individuals; 65 877 events) were 1·18 (95% CI 1·08–1·29), 1·10 (1·00–1·22), and 1·05 (0·92–1·20), respectively, per 1 SD increment in plasma urate.
Interpretation
Conventional and multivariate Mendelian randomisation analysis implicates a causal role for urate in the development of coronary heart disease, but these estimates might be inflated by hidden pleiotropy. Egger Mendelian randomisation analysis, which accounts for pleiotropy but has less statistical power, suggests there might be no causal effect. These results might help investigators to determine the priority of trials of urate lowering for the prevention of coronary heart disease compared with other potential interventions.
Funding
UK National Institute for Health Research, British Heart Foundation, and UK Medical Research Council.
doi:10.1016/S2213-8587(15)00386-1
PMCID: PMC4805857  PMID: 26781229
2.  Post-GWAS methodologies for localisation of functional non-coding variants: ANGPTL3 
Atherosclerosis  2016;246:193-201.
Genome-wide association studies have confirmed the involvement of non-coding angiopoietin-like 3 (ANGPTL3) gene variants with coronary artery disease, levels of low-density lipoprotein cholesterol (LDL-C), triglycerides and ANGPTL3 mRNA transcript. Extensive linkage disequilibrium at the locus, however, has hindered efforts to identify the potential functional variants. Using regulatory annotations from ENCODE, combined with functional in vivo assays such as allele-specific formaldehyde-assisted isolation of regulatory elements, statistical approaches including eQTL/lipid colocalisation, and traditional in vitro methodologies including electrophoretic mobility shift assay and luciferase reporter assays, variants affecting the ANGPTL3 regulome were examined. From 253 variants associated with ANGPTL3 mRNA expression, and/or lipid traits, 46 were located within liver regulatory elements and potentially functional. One variant, rs10889352, demonstrated allele-specific effects on DNA-protein interactions, reporter gene expression and chromatin accessibility, in line with effects on LDL-C levels and expression of ANGPTL3 mRNA. The ANGPTL3 gene lies within DOCK7, although the variant is within non-coding regions outside of ANGPTL3, within DOCK7, suggesting complex long-range regulatory effects on gene expression. This study illustrates the power of combining multiple genome-wide datasets with laboratory data to localise functional non-coding variation and provides a model for analysis of regulatory variants from GWAS.
Highlights
•Over 200 variants exist in strong linkage disequilibrium with the lead ANGPTL3 SNP locus.•rs10889352 affects DNA-protein interactions from liver nuclear extract.•rs10889352 affects reporter gene expression in liver cells.•rs10889352 is associated with chromatin accessibility.•Effects on ANGPTL3 gene expression and lipid levels is likely due to rs10889352.
doi:10.1016/j.atherosclerosis.2015.12.009
PMCID: PMC4773290  PMID: 26800306
ANGPTL3; Polymorphism; Regulation; Chromatin; Genome-wide; Functional polymorphism; FAIRE; LDL-C; GWAS, genome-wide association study; LDL-C, low density lipoprotein cholesterol; HDL-C, high density lipoprotein cholesterol; TG, triglycerides; EMSA, electrophoretic mobility shift assay; SNP, single nucleotide polymorphism
3.  D25V apolipoprotein C-III variant causes dominant hereditary systemic amyloidosis and confers cardiovascular protective lipoprotein profile 
Nature Communications  2016;7:10353.
Apolipoprotein C-III deficiency provides cardiovascular protection, but apolipoprotein C-III is not known to be associated with human amyloidosis. Here we report a form of amyloidosis characterized by renal insufficiency caused by a new apolipoprotein C-III variant, D25V. Despite their uremic state, the D25V-carriers exhibit low triglyceride (TG) and apolipoprotein C-III levels, and low very-low-density lipoprotein (VLDL)/high high-density lipoprotein (HDL) profile. Amyloid fibrils comprise the D25V-variant only, showing that wild-type apolipoprotein C-III does not contribute to amyloid deposition in vivo. The mutation profoundly impacts helical structure stability of D25V-variant, which is remarkably fibrillogenic under physiological conditions in vitro producing typical amyloid fibrils in its lipid-free form. D25V apolipoprotein C-III is a new human amyloidogenic protein and the first conferring cardioprotection even in the unfavourable context of renal failure, extending the evidence for an important cardiovascular protective role of apolipoprotein C-III deficiency. Thus, fibrate therapy, which reduces hepatic APOC3 transcription, may delay amyloid deposition in affected patients.
Decrease in Apolipoprotein C-III (ApoC-III) yields a cardioprotective lipoprotein profile. Here, Valleix et al. reveal a novel ApoC-III variant conferring low plasma ApoC-III concentration and cardioprotection despite renal insufficiency, and, unexpectedly, causing dominant hereditary systemic amyloidosis due to its fibrillogenic nature.
doi:10.1038/ncomms10353
PMCID: PMC4735822  PMID: 26790392
5.  A Novel Genetic Approach to Investigate the Role of Plasma Secretory Phospholipase A2 (sPLA2)-V Isoenzyme in Coronary Heart Disease: A Modified Mendelian Randomization Analysis Using PLA2G5 Expression Levels 
Background
Secretory phospholipase A2 (sPLA2) enzymes are considered to play a role in atherosclerosis. sPLA2 activity encompasses several sPLA2 isoenzymes, including sPLA2-V. While observational studies show strong association between elevated sPLA2 activity and CHD, no assay to measure sPLA2-V levels exists and the only evidence linking the sPLA2-V isoform to atherosclerosis progression comes from animal studies. In the absence of an assay that directly quantifies sPLA2-V levels, we used PLA2G5 mRNA levels in a novel, modified Mendelian randomization approach to investigate the hypothesized causal role of sPLA2-V in coronary heart disease (CHD) pathogenesis.
Methods and Results
Using data from the Advanced Study of Aortic Pathology, we identified the single nucleotide polymorphism (SNP) in PLA2G5 showing strongest association with PLA2G5 mRNA expression levels, as a proxy for sPLA2-V levels. We tested the association of this SNP with sPLA2 activity and CHD events in four prospective and 14 case-control studies with 27,230 events and 70,500 controls. rs525380C>A showed the strongest association with PLA2G5 mRNA expression (P=5.1×10−6). There was no association of rs525380C>A with plasma sPLA2 activity (difference in geometric mean of sPLA2 activity per rs525380 A-allele 0.4% (95%CI: −0.9%, 1.6%), P=0.56). In meta-analyses, the odds ratio for CHD per A allele was 1.02 (95% CI: 0.99, 1.04; P=0.20).
Conclusions
This novel approach for SNP selection for this modified Mendelian randomization analysis showed no association between rs525380 (the lead SNP for PLA2G5 expression, a surrogate for sPLA2-V levels) and CHD events. The evidence does not support a causal role for sPLA2-V in CHD.
doi:10.1161/CIRCGENETICS.113.000271
PMCID: PMC4212409  PMID: 24563418
Mendelian randomization; cardiovascular disease risk factors; DNA polymorphisms; GATA2; sPLA2-V; PLA2G5
6.  Demonstration of the Presence of the “Deleted” MIR122 Gene in HepG2 Cells 
PLoS ONE  2015;10(3):e0122471.
MicroRNA 122 (miR-122) is highly expressed in the liver where it influences diverse biological processes and pathways, including hepatitis C virus replication and metabolism of iron and cholesterol. It is processed from a long non-coding primary transcript (~7.5 kb) and the gene has two evolutionarily-conserved regions containing the pri-mir-122 promoter and pre-mir-122 hairpin region. Several groups reported that the widely-used hepatocytic cell line HepG2 had deficient expression of miR-122, previously ascribed to deletion of the pre-mir-122 stem-loop region. We aimed to characterise this deletion by direct sequencing of 6078 bp containing the pri-mir-122 promoter and pre-mir-122 stem-loop region in HepG2 and Huh-7, a control hepatocytic cell line reported to express miR-122, supported by sequence analysis of cloned genomic DNA. In contrast to previous findings, the entire sequence was present in both cell lines. Ten SNPs were heterozygous in HepG2 indicating that DNA was present in two copies. Three validation isolates of HepG2 were sequenced, showing identical genotype to the original in two, whereas the third was different. Investigation of promoter chromatin status by FAIRE showed that Huh-7 cells had 6.2 ± 0.19- and 2.7 ± 0.01- fold more accessible chromatin at the proximal (HNF4α-binding) and distal DR1 transcription factor sites, compared to HepG2 cells (p=0.03 and 0.001, respectively). This was substantiated by ENCODE genome annotations, which showed a DNAse I hypersensitive site in the pri-mir-122 promoter in Huh-7 that was absent in HepG2 cells. While the origin of the reported deletion is unclear, cell lines should be obtained from a reputable source and used at low passage number to avoid discrepant results. Deficiency of miR-122 expression in HepG2 cells may be related to a relative deficiency of accessible promoter chromatin in HepG2 versus Huh-7 cells.
doi:10.1371/journal.pone.0122471
PMCID: PMC4374784  PMID: 25811611
7.  A rare variant in APOC3 is associated with plasma triglyceride and VLDL levels in Europeans 
Nature communications  2014;5:4871.
The analysis of rich catalogues of genetic variation from population-based sequencing provides an opportunity to screen for functional effects. Here we report a rare variant in APOC3 (rs138326449-A, minor allele frequency ~0.25% (UK)) associated with plasma triglyceride (TG) levels (−1.43 standard deviations (standard error (s.e.=0.27) per minor allele (p-value=8.0×10−8)) discovered in 3202 individuals with low read-depth, whole genome sequence. We replicate this in 12831 participants from five additional samples of Northern and Southern European origin (−1.0 standard deviation (s.e.=0.173), p-value=7.32×10−9). This is consistent with an effect between 0.5 and 1.5mmol/L dependent on population. We show that a single predicted splice donor variant is responsible for association signals and is independent of known common variants. Analyses suggest an independent relationship between rs138326449 and high-density lipoprotein (HDL) levels. This represents one of the first examples of a rare, large effect variant identified from whole-genome sequencing at a population scale.
doi:10.1038/ncomms5871
PMCID: PMC4167609  PMID: 25225788
Whole genome sequence; triglycerides; APOC3
8.  HMG-coenzyme A reductase inhibition, type 2 diabetes, and bodyweight: evidence from genetic analysis and randomised trials 
Swerdlow, Daniel I | Preiss, David | Kuchenbaecker, Karoline B | Holmes, Michael V | Engmann, Jorgen E L | Shah, Tina | Sofat, Reecha | Stender, Stefan | Johnson, Paul C D | Scott, Robert A | Leusink, Maarten | Verweij, Niek | Sharp, Stephen J | Guo, Yiran | Giambartolomei, Claudia | Chung, Christina | Peasey, Anne | Amuzu, Antoinette | Li, KaWah | Palmen, Jutta | Howard, Philip | Cooper, Jackie A | Drenos, Fotios | Li, Yun R | Lowe, Gordon | Gallacher, John | Stewart, Marlene C W | Tzoulaki, Ioanna | Buxbaum, Sarah G | van der A, Daphne L | Forouhi, Nita G | Onland-Moret, N Charlotte | van der Schouw, Yvonne T | Schnabel, Renate B | Hubacek, Jaroslav A | Kubinova, Ruzena | Baceviciene, Migle | Tamosiunas, Abdonas | Pajak, Andrzej | Topor-Madry, Romanvan | Stepaniak, Urszula | Malyutina, Sofia | Baldassarre, Damiano | Sennblad, Bengt | Tremoli, Elena | de Faire, Ulf | Veglia, Fabrizio | Ford, Ian | Jukema, J Wouter | Westendorp, Rudi G J | de Borst, Gert Jan | de Jong, Pim A | Algra, Ale | Spiering, Wilko | der Zee, Anke H Maitland-van | Klungel, Olaf H | de Boer, Anthonius | Doevendans, Pieter A | Eaton, Charles B | Robinson, Jennifer G | Duggan, David | Kjekshus, John | Downs, John R | Gotto, Antonio M | Keech, Anthony C | Marchioli, Roberto | Tognoni, Gianni | Sever, Peter S | Poulter, Neil R | Waters, David D | Pedersen, Terje R | Amarenco, Pierre | Nakamura, Haruo | McMurray, John J V | Lewsey, James D | Chasman, Daniel I | Ridker, Paul M | Maggioni, Aldo P | Tavazzi, Luigi | Ray, Kausik K | Seshasai, Sreenivasa Rao Kondapally | Manson, JoAnn E | Price, Jackie F | Whincup, Peter H | Morris, Richard W | Lawlor, Debbie A | Smith, George Davey | Ben-Shlomo, Yoav | Schreiner, Pamela J | Fornage, Myriam | Siscovick, David S | Cushman, Mary | Kumari, Meena | Wareham, Nick J | Verschuren, W M Monique | Redline, Susan | Patel, Sanjay R | Whittaker, John C | Hamsten, Anders | Delaney, Joseph A | Dale, Caroline | Gaunt, Tom R | Wong, Andrew | Kuh, Diana | Hardy, Rebecca | Kathiresan, Sekar | Castillo, Berta A | van der Harst, Pim | Brunner, Eric J | Tybjaerg-Hansen, Anne | Marmot, Michael G | Krauss, Ronald M | Tsai, Michael | Coresh, Josef | Hoogeveen, Ronald C | Psaty, Bruce M | Lange, Leslie A | Hakonarson, Hakon | Dudbridge, Frank | Humphries, Steve E | Talmud, Philippa J | Kivimäki, Mika | Timpson, Nicholas J | Langenberg, Claudia | Asselbergs, Folkert W | Voevoda, Mikhail | Bobak, Martin | Pikhart, Hynek | Wilson, James G | Reiner, Alex P | Keating, Brendan J | Hingorani, Aroon D | Sattar, Naveed
Lancet  2015;385(9965):351-361.
Summary
Background
Statins increase the risk of new-onset type 2 diabetes mellitus. We aimed to assess whether this increase in risk is a consequence of inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the intended drug target.
Methods
We used single nucleotide polymorphisms in the HMGCR gene, rs17238484 (for the main analysis) and rs12916 (for a subsidiary analysis) as proxies for HMGCR inhibition by statins. We examined associations of these variants with plasma lipid, glucose, and insulin concentrations; bodyweight; waist circumference; and prevalent and incident type 2 diabetes. Study-specific effect estimates per copy of each LDL-lowering allele were pooled by meta-analysis. These findings were compared with a meta-analysis of new-onset type 2 diabetes and bodyweight change data from randomised trials of statin drugs. The effects of statins in each randomised trial were assessed using meta-analysis.
Findings
Data were available for up to 223 463 individuals from 43 genetic studies. Each additional rs17238484-G allele was associated with a mean 0·06 mmol/L (95% CI 0·05–0·07) lower LDL cholesterol and higher body weight (0·30 kg, 0·18–0·43), waist circumference (0·32 cm, 0·16–0·47), plasma insulin concentration (1·62%, 0·53–2·72), and plasma glucose concentration (0·23%, 0·02–0·44). The rs12916 SNP had similar effects on LDL cholesterol, bodyweight, and waist circumference. The rs17238484-G allele seemed to be associated with higher risk of type 2 diabetes (odds ratio [OR] per allele 1·02, 95% CI 1·00–1·05); the rs12916-T allele association was consistent (1·06, 1·03–1·09). In 129 170 individuals in randomised trials, statins lowered LDL cholesterol by 0·92 mmol/L (95% CI 0·18–1·67) at 1-year of follow-up, increased bodyweight by 0·24 kg (95% CI 0·10–0·38 in all trials; 0·33 kg, 95% CI 0·24–0·42 in placebo or standard care controlled trials and −0·15 kg, 95% CI −0·39 to 0·08 in intensive-dose vs moderate-dose trials) at a mean of 4·2 years (range 1·9–6·7) of follow-up, and increased the odds of new-onset type 2 diabetes (OR 1·12, 95% CI 1·06–1·18 in all trials; 1·11, 95% CI 1·03–1·20 in placebo or standard care controlled trials and 1·12, 95% CI 1·04–1·22 in intensive-dose vs moderate dose trials).
Interpretation
The increased risk of type 2 diabetes noted with statins is at least partially explained by HMGCR inhibition.
Funding
The funding sources are cited at the end of the paper.
doi:10.1016/S0140-6736(14)61183-1
PMCID: PMC4322187  PMID: 25262344
9.  A systematic review and meta-analysis of 130,000 individuals shows smoking does not modify the association of APOE genotype on risk of coronary heart disease 
Atherosclerosis  2014;237(1):5-12.
Background
Conflicting evidence exists on whether smoking acts as an effect modifier of the association between APOE genotype and risk of coronary heart disease (CHD).
Methods and results
We searched PubMed and EMBASE to June 11, 2013 for published studies reporting APOE genotype, smoking status and CHD events and added unpublished data from population cohorts. We tested for presence of effect modification by smoking status in the relationship between APOE genotype and risk of CHD using likelihood ratio test.
In total 13 studies (including unpublished data from eight cohorts) with 10,134 CHD events in 130,004 individuals of European descent were identified. The odds ratio (OR) for CHD risk from APOE genotype (ε4 carriers versus non-carriers) was 1.06 (95% confidence interval (CI): 1.01, 1.12) and for smoking (present vs. past/never smokers) was OR 2.05 (95%CI: 1.95, 2.14). When the association between APOE genotype and CHD was stratified by smoking status, compared to non-ε4 carriers, ε4 carriers had an OR of 1.11 (95%CI: 1.02, 1.21) in 28,789 present smokers and an OR of 1.04 (95%CI 0.98, 1.10) in 101,215 previous/never smokers, with no evidence of effect modification (P-value for heterogeneity = 0.19). Analysis of pack years in individual participant data of >60,000 with adjustment for cardiovascular traits also failed to identify evidence of effect modification.
Conclusions
In the largest analysis to date, we identified no evidence for effect modification by smoking status in the association between APOE genotype and risk of CHD.
Highlights
•We examined evidence for an interaction between APOE genotype, smoking and risk of coronary heart disease.•This was conducted in the largest meta-analysis of published and unpublished data sets to date (>130,000 individuals).•Our analysis did not identify evidence of interaction.•These findings bring into question presence of a clinically meaningful interaction between APOE genotype and smoking.
doi:10.1016/j.atherosclerosis.2014.07.038
PMCID: PMC4232362  PMID: 25173947
APOE genotype; Smoking; Coronary heart disease; Gene–environment interaction
10.  A rare variant in APOC3 is associated with plasma triglyceride and VLDL levels in Europeans 
Nature Communications  2014;5:4871.
The analysis of rich catalogues of genetic variation from population-based sequencing provides an opportunity to screen for functional effects. Here we report a rare variant in APOC3 (rs138326449-A, minor allele frequency ~0.25% (UK)) associated with plasma triglyceride (TG) levels (−1.43 s.d. (s.e.=0.27 per minor allele (P-value=8.0 × 10−8)) discovered in 3,202 individuals with low read-depth, whole-genome sequence. We replicate this in 12,831 participants from five additional samples of Northern and Southern European origin (−1.0 s.d. (s.e.=0.173), P-value=7.32 × 10−9). This is consistent with an effect between 0.5 and 1.5 mmol l−1 dependent on population. We show that a single predicted splice donor variant is responsible for association signals and is independent of known common variants. Analyses suggest an independent relationship between rs138326449 and high-density lipoprotein (HDL) levels. This represents one of the first examples of a rare, large effect variant identified from whole-genome sequencing at a population scale.
Population-based genome sequencing provides an increasingly rich resource for the identification of low-frequency, large effect variants associated with clinically important phenotypes. Timpson et al. use UK10K data to identify a variant of the APOC3 gene strongly associated with plasma triglyceride levels.
doi:10.1038/ncomms5871
PMCID: PMC4167609  PMID: 25225788
11.  Gene-centric association signals for haemostasis and thrombosis traits identified with the HumanCVD BeadChip 
Thrombosis and haemostasis  2013;110(5):995-1003.
Summary
Objective
Coagulation phenotypes show strong intercorrelations, affect cardiovascular disease risk and are influenced by genetic variants. The objective of this study was to search for novel genetic variants influencing the following coagulation phenotypes: factor VII levels, fibrinogen levels, plasma viscosity and platelet count.
Methods and Results
We genotyped the British Women’s Heart and Health Study (n=3445) and the Whitehall II study (n=5059) using the Illumina HumanCVD BeadArray to investigate genetic associations and pleiotropy. In addition to previously reported associations (SH2B3, F7/F10, PROCR, GCKR, FGA/FGB/FGG, IL5), we identified novel associations at GRK5 (rs10128498, p=1.30×10−6), GCKR (rs1260326, p=1.63×10−6), ZNF259-APOA5 (rs651821, p=7.17×10−6) with plasma viscosity; and at CSF1 (rs333948, p=8.88×10−6) with platelet count. A pleiotropic effect was identified in GCKR which associated with factor VII (p=2.16×10−7) and plasma viscosity (p=1.63×10−6), and, to a lesser extent, ZNF259-APOA5 which associated with factor VII and fibrinogen (p<1.00×10−2) and additionally plasma viscosity (p<1.00×10−5). Triglyceride associated variants were overrepresented in Factor VII and plasma viscosity associations. Adjusting for triglyceride levels resulted in attenuation of associations at the GCKR and ZNF259-APOA5 loci.
Conclusions
In addition to confirming previously reported associations, we identified four SNPs associated with plasma viscosity and platelet count and found evidence of pleiotropic effects with SNPs in GCKR and ZNF259-APOA5. These triglyceride-associated, pleiotropic SNPs suggest a possible causal role for triglycerides in coagulation.
doi:10.1160/TH13-02-0087
PMCID: PMC4067543  PMID: 24178511
Haemostasis; Thrombosis; HumanCVD; Clotting Factors; Genetic Association
12.  Identification of seven loci affecting mean telomere length and their association with disease 
Codd, Veryan | Nelson, Christopher P. | Albrecht, Eva | Mangino, Massimo | Deelen, Joris | Buxton, Jessica L. | Jan Hottenga, Jouke | Fischer, Krista | Esko, Tõnu | Surakka, Ida | Broer, Linda | Nyholt, Dale R. | Mateo Leach, Irene | Salo, Perttu | Hägg, Sara | Matthews, Mary K. | Palmen, Jutta | Norata, Giuseppe D. | O’Reilly, Paul F. | Saleheen, Danish | Amin, Najaf | Balmforth, Anthony J. | Beekman, Marian | de Boer, Rudolf A. | Böhringer, Stefan | Braund, Peter S. | Burton, Paul R. | de Craen, Anton J. M. | Denniff, Matthew | Dong, Yanbin | Douroudis, Konstantinos | Dubinina, Elena | Eriksson, Johan G. | Garlaschelli, Katia | Guo, Dehuang | Hartikainen, Anna-Liisa | Henders, Anjali K. | Houwing-Duistermaat, Jeanine J. | Kananen, Laura | Karssen, Lennart C. | Kettunen, Johannes | Klopp, Norman | Lagou, Vasiliki | van Leeuwen, Elisabeth M. | Madden, Pamela A. | Mägi, Reedik | Magnusson, Patrik K.E. | Männistö, Satu | McCarthy, Mark I. | Medland, Sarah E. | Mihailov, Evelin | Montgomery, Grant W. | Oostra, Ben A. | Palotie, Aarno | Peters, Annette | Pollard, Helen | Pouta, Anneli | Prokopenko, Inga | Ripatti, Samuli | Salomaa, Veikko | Suchiman, H. Eka D. | Valdes, Ana M. | Verweij, Niek | Viñuela, Ana | Wang, Xiaoling | Wichmann, H.-Erich | Widen, Elisabeth | Willemsen, Gonneke | Wright, Margaret J. | Xia, Kai | Xiao, Xiangjun | van Veldhuisen, Dirk J. | Catapano, Alberico L. | Tobin, Martin D. | Hall, Alistair S. | Blakemore, Alexandra I.F. | van Gilst, Wiek H. | Zhu, Haidong | Erdmann, Jeanette | Reilly, Muredach P. | Kathiresan, Sekar | Schunkert, Heribert | Talmud, Philippa J. | Pedersen, Nancy L. | Perola, Markus | Ouwehand, Willem | Kaprio, Jaakko | Martin, Nicholas G. | van Duijn, Cornelia M. | Hovatta, Iiris | Gieger, Christian | Metspalu, Andres | Boomsma, Dorret I. | Jarvelin, Marjo-Riitta | Slagboom, P. Eline | Thompson, John R. | Spector, Tim D. | van der Harst, Pim | Samani, Nilesh J.
Nature genetics  2013;45(4):422-427e2.
Inter-individual variation in mean leukocyte telomere length (LTL) is associated with cancer and several age-associated diseases. Here, in a genome-wide meta-analysis of 37,684 individuals with replication of selected variants in a further 10,739 individuals, we identified seven loci, including five novel loci, associated with mean LTL (P<5x10−8). Five of the loci contain genes (TERC, TERT, NAF1, OBFC1, RTEL1) that are known to be involved in telomere biology. Lead SNPs at two loci (TERC and TERT) associate with several cancers and other diseases, including idiopathic pulmonary fibrosis. Moreover, a genetic risk score analysis combining lead variants at all seven loci in 22,233 coronary artery disease cases and 64,762 controls showed an association of the alleles associated with shorter LTL with increased risk of CAD (21% (95% CI: 5–35%) per standard deviation in LTL, p=0.014). Our findings support a causal role of telomere length variation in some age-related diseases.
doi:10.1038/ng.2528
PMCID: PMC4006270  PMID: 23535734
13.  Meta analysis of candidate gene variants outside the LPA locus with Lp(a) plasma levels in 14,500 participants of six White European cohorts 
Atherosclerosis  2011;217(2):447-451.
Background
Both genome-wide association studies and candidate gene studies have reported that the major determinant of plasma levels of the Lipoprotein (a) [Lp(a)] reside within the LPA locus on chromosome 6. We have used data from the Human CVD bead chip to explore the contribution of other candidate genes determining Lp(a) levels.
Methods
48,032 single nucleotide polymorphisms (SNPs) from the Illumina Human CVD bead chip were genotyped in 5,059 participants of the Whitehall II study (WHII) of randomly ascertained healthy men and women. SNPs showing association with Lp(a) levels of p< 10−4 outside the LPA locus were selected for replication in a total of an additional 9,463 participants of five European based studies (EAS, EPIC-Norfolk, NPHSII, PROCARDIS, and SAPHIR)
Results
In Whitehall II, apart from the LPA locus (where p values for several SNPs were < 10−30) there was significant association at four loci GALNT2, FABP1, PPARGC1A and TNFRSFF11A. However, a meta-analysis of the six studies did not confirm any of these findings.
Conclusion
Results from this meta analysis of 14,522 participants revealed no candidate genes from the Human CVD bead chip outside the LPA locus to have an effect on Lp(a) levels. Further studies with genome-wide and denser SNP coverage are required to confirm or refute this finding.
doi:10.1016/j.atherosclerosis.2011.04.015
PMCID: PMC3972487  PMID: 21592478
Lipoprotein(a); LPA; Illumina Human CVD bead chip; genetic association
14.  Influence of common genetic variation on blood lipid levels, cardiovascular risk, and coronary events in two British prospective cohort studies 
European Heart Journal  2012;34(13):972-981.
Aims
The aim of this study was to quantify the collective effect of common lipid-associated single nucleotide polymorphisms (SNPs) on blood lipid levels, cardiovascular risk, use of lipid-lowering medication, and risk of coronary heart disease (CHD) events.
Methods and results
Analysis was performed in two prospective cohorts: Whitehall II (WHII; N = 5059) and the British Women’s Heart and Health Study (BWHHS; N = 3414). For each participant, scores were calculated based on the cumulative effect of multiple genetic variants influencing total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG). Compared with the bottom quintile, individuals in the top quintile of the LDL-C genetic score distribution had higher LDL-C {mean difference of 0.85 [95% confidence interval, (CI) = 0.76–0.94] and 0.63 [95% CI = 0.50–0.76] mmol/l in WHII and BWHHS, respectively}. They also tended to have greater odds of having ‘high-risk’ status (Framingham 10-year cardiovascular disease risk >20%) [WHII: odds ratio (OR) = 1.36 (0.93–1.98), BWHHS: OR = 1.49 (1.14–1.94)]; receiving lipid-lowering treatment [WHII: OR = 2.38 (1.57–3.59), BWHHS: OR = 2.24 (1.52–3.29)]; and CHD events [WHII: OR = 1.43 (1.02–2.00), BWHHS: OR = 1.31 (0.99–1.72)]. Similar associations were observed for the TC score in both studies. The TG score was associated with high-risk status and medication use in both studies. Neither HDL nor TG scores were associated with the risk of coronary events. The genetic scores did not improve discrimination over the Framingham risk score.
Conclusion
At the population level, common SNPs associated with LDL-C and TC contribute to blood lipid variation, cardiovascular risk, use of lipid-lowering medications and coronary events. However, their effects are too small to discriminate future lipid-lowering medication requirements or coronary events.
doi:10.1093/eurheartj/ehs243
PMCID: PMC3612774  PMID: 22977227
Lipid genetic score; Lipid medication; Framingham
15.  Apolipoprotein E genotype, cardiovascular biomarkers and risk of stroke: Systematic review and meta-analysis of 14 015 stroke cases and pooled analysis of primary biomarker data from up to 60 883 individuals 
Background At the APOE gene, encoding apolipoprotein E, genotypes of the ε2/ε3/ε4 alleles associated with higher LDL-cholesterol (LDL-C) levels are also associated with higher coronary risk. However, the association of APOE genotype with other cardiovascular biomarkers and risk of ischaemic stroke is less clear. We evaluated the association of APOE genotype with risk of ischaemic stroke and assessed whether the observed effect was consistent with the effects of APOE genotype on LDL-C or other lipids and biomarkers of cardiovascular risk.
Methods We conducted a systematic review of published and unpublished studies reporting on APOE genotype and ischaemic stroke. We pooled 41 studies (with a total of 9027 cases and 61 730 controls) using a Bayesian meta-analysis to calculate the odds ratios (ORs) for ischaemic stroke with APOE genotype. To better evaluate potential mechanisms for any observed effect, we also conducted a pooled analysis of primary data using 16 studies (up to 60 883 individuals) of European ancestry. We evaluated the association of APOE genotype with lipids, other circulating biomarkers of cardiovascular risk and carotid intima-media thickness (C-IMT).
Results The ORs for association of APOE genotypes with ischaemic stroke were: 1.09 (95% credible intervals (CrI): 0.84–1.43) for ε2/ε2; 0.85 (95% CrI: 0.78–0.92) for ε2/ε3; 1.05 (95% CrI: 0.89–1.24) for ε2/ε4; 1.05 (95% CrI: 0.99–1.12) for ε3/ε4; and 1.12 (95% CrI: 0.94–1.33) for ε4/ε4 using the ε3/ε3 genotype as the reference group. A regression analysis that investigated the effect of LDL-C (using APOE as the instrument) on ischaemic stroke showed a positive dose-response association with an OR of 1.33 (95% CrI: 1.17, 1.52) per 1 mmol/l increase in LDL-C. In the separate pooled analysis, APOE genotype was linearly and positively associated with levels of LDL-C (P-trend: 2 × 10−152), apolipoprotein B (P-trend: 8.7 × 10−06) and C-IMT (P-trend: 0.001), and negatively and linearly associated with apolipoprotein E (P-trend: 6 × 10−26) and HDL-C (P-trend: 1.6 × 10−12). Associations with lipoprotein(a), C-reactive protein and triglycerides were non-linear.
Conclusions In people of European ancestry, APOE genotype showed a positive dose-response association with LDL-C, C-IMT and ischaemic stroke. However, the association of APOE ε2/ε2 genotype with ischaemic stroke requires further investigation. This cross-domain concordance supports a causal role of LDL-C on ischaemic stroke.
doi:10.1093/ije/dyt034
PMCID: PMC3619955  PMID: 23569189
Stroke; lipids; apolipoprotein E; cardiovascular disease; systematic review; meta-analysis; biomarkers
16.  From zebrafish heart jogging genes to mouse and human orthologs: using Gene Ontology to investigate mammalian heart development. 
F1000Research  2014;2:242.
For the majority of organs in developing vertebrate embryos, left-right asymmetry is controlled by a ciliated region; the left-right organizer node in the mouse and human, and the Kuppfer’s vesicle in the zebrafish. In the zebrafish, laterality cues from the Kuppfer’s vesicle determine asymmetry in the developing heart, the direction of ‘heart jogging’ and the direction of ‘heart looping’.  ‘Heart jogging’ is the term given to the process by which the symmetrical zebrafish heart tube is displaced relative to the dorsal midline, with a leftward ‘jog’. Heart jogging is not considered to occur in mammals, although a leftward shift of the developing mouse caudal heart does occur prior to looping, which may be analogous to zebrafish heart jogging. Previous studies have characterized 30 genes involved in zebrafish heart jogging, the majority of which have well defined orthologs in mouse and human and many of these orthologs have been associated with early mammalian heart development. 
 
We undertook manual curation of a specific set of genes associated with heart development and we describe the use of Gene Ontology term enrichment analyses to examine the cellular processes associated with heart jogging.  We found that the human, mouse and zebrafish ‘heart jogging orthologs’ are involved in similar organ developmental processes across the three species, such as heart, kidney and nervous system development, as well as more specific cellular processes such as cilium development and function. The results of these analyses are consistent with a role for cilia in the determination of left-right asymmetry of many internal organs, in addition to their known role in zebrafish heart jogging. 
 
This study highlights the importance of model organisms in the study of human heart development, and emphasises both the conservation and divergence of developmental processes across vertebrates, as well as the limitations of this approach.
doi:10.12688/f1000research.2-242.v2
PMCID: PMC3931453  PMID: 24627794
17.  Mendelian randomization of blood lipids for coronary heart disease 
European Heart Journal  2014;36(9):539-550.
Aims
To investigate the causal role of high-density lipoprotein cholesterol (HDL-C) and triglycerides in coronary heart disease (CHD) using multiple instrumental variables for Mendelian randomization.
Methods and results
We developed weighted allele scores based on single nucleotide polymorphisms (SNPs) with established associations with HDL-C, triglycerides, and low-density lipoprotein cholesterol (LDL-C). For each trait, we constructed two scores. The first was unrestricted, including all independent SNPs associated with the lipid trait identified from a prior meta-analysis (threshold P < 2 × 10−6); and the second a restricted score, filtered to remove any SNPs also associated with either of the other two lipid traits at P ≤ 0.01. Mendelian randomization meta-analyses were conducted in 17 studies including 62,199 participants and 12,099 CHD events. Both the unrestricted and restricted allele scores for LDL-C (42 and 19 SNPs, respectively) associated with CHD. For HDL-C, the unrestricted allele score (48 SNPs) was associated with CHD (OR: 0.53; 95% CI: 0.40, 0.70), per 1 mmol/L higher HDL-C, but neither the restricted allele score (19 SNPs; OR: 0.91; 95% CI: 0.42, 1.98) nor the unrestricted HDL-C allele score adjusted for triglycerides, LDL-C, or statin use (OR: 0.81; 95% CI: 0.44, 1.46) showed a robust association. For triglycerides, the unrestricted allele score (67 SNPs) and the restricted allele score (27 SNPs) were both associated with CHD (OR: 1.62; 95% CI: 1.24, 2.11 and 1.61; 95% CI: 1.00, 2.59, respectively) per 1-log unit increment. However, the unrestricted triglyceride score adjusted for HDL-C, LDL-C, and statin use gave an OR for CHD of 1.01 (95% CI: 0.59, 1.75).
Conclusion
The genetic findings support a causal effect of triglycerides on CHD risk, but a causal role for HDL-C, though possible, remains less certain.
doi:10.1093/eurheartj/eht571
PMCID: PMC4344957  PMID: 24474739
Lipids; Heart disease; Mendelian randomization; Aetiology; Epidemiology
18.  Association of TERC and OBFC1 Haplotypes with Mean Leukocyte Telomere Length and Risk for Coronary Heart Disease  
PLoS ONE  2013;8(12):e83122.
Objective
To replicate the associations of leukocyte telomere length (LTL) with variants at four loci and to investigate their associations with coronary heart disease (CHD) and type II diabetes (T2D), in order to examine possible causal effects of telomere maintenance machinery on disease aetiology.
Methods
Four SNPs at three loci BICD1 (rs2630578 GγC), 18q12.2 (rs2162440 GγT), and OBFC1 (rs10786775 CγG, rs11591710 AγC) were genotyped in four studies comprised of 2353 subjects out of which 1148 had CHD and 566 T2D. Three SNPs (rs12696304 CγG, rs10936601G>T and rs16847897 GγC) at the TERC locus were genotyped in these four studies, in addition to an offspring study of 765 healthy students. For all samples, LTL had been measured using a real-time PCR-based method.
Results
Only one SNP was associated with a significant effect on LTL, with the minor allele G of OBFC1 rs10786775 SNP being associated with longer LTL (β=0.029, P=0.04). No SNPs were significantly associated with CHD or T2D. For OBFC1 the haplotype carrying both rare alleles (rs10786775G and rs11591710C, haplotype frequency 0.089) was associated with lower CHD prevalence (OR: 0.77; 95% CI: 0.61–0.97; P= 0.03). The TERC haplotype GTC (rs12696304G, rs10936601T and rs16847897C, haplotype frequency 0.210) was associated with lower risk for both CHD (OR: 0.86; 95% CI: 0.75-0.99; P=0.04) and T2D (OR: 0.74; 95% CI: 0.61–0.91; P= 0.004), with no effect on LTL. Only the last association remained after adjusting for multiple testing.
Conclusion
Of reported associations, only that between the OBFC1 rs10786775 SNP and LTL was confirmed, although our study has a limited power to detect modest effects. A 2-SNP OBFC1 haplotype was associated with higher risk of CHD, and a 3-SNP TERC haplotype was associated with both higher risk of CHD and T2D. Further work is required to confirm these results and explore the mechanisms of these effects.
doi:10.1371/journal.pone.0083122
PMCID: PMC3861448  PMID: 24349443
19.  Secretory Phospholipase A2-IIA and Cardiovascular Disease 
Holmes, Michael V. | Simon, Tabassome | Exeter, Holly J. | Folkersen, Lasse | Asselbergs, Folkert W. | Guardiola, Montse | Cooper, Jackie A. | Palmen, Jutta | Hubacek, Jaroslav A. | Carruthers, Kathryn F. | Horne, Benjamin D. | Brunisholz, Kimberly D. | Mega, Jessica L. | van Iperen, Erik P.A. | Li, Mingyao | Leusink, Maarten | Trompet, Stella | Verschuren, Jeffrey J.W. | Hovingh, G. Kees | Dehghan, Abbas | Nelson, Christopher P. | Kotti, Salma | Danchin, Nicolas | Scholz, Markus | Haase, Christiane L. | Rothenbacher, Dietrich | Swerdlow, Daniel I. | Kuchenbaecker, Karoline B. | Staines-Urias, Eleonora | Goel, Anuj | van 't Hooft, Ferdinand | Gertow, Karl | de Faire, Ulf | Panayiotou, Andrie G. | Tremoli, Elena | Baldassarre, Damiano | Veglia, Fabrizio | Holdt, Lesca M. | Beutner, Frank | Gansevoort, Ron T. | Navis, Gerjan J. | Mateo Leach, Irene | Breitling, Lutz P. | Brenner, Hermann | Thiery, Joachim | Dallmeier, Dhayana | Franco-Cereceda, Anders | Boer, Jolanda M.A. | Stephens, Jeffrey W. | Hofker, Marten H. | Tedgui, Alain | Hofman, Albert | Uitterlinden, André G. | Adamkova, Vera | Pitha, Jan | Onland-Moret, N. Charlotte | Cramer, Maarten J. | Nathoe, Hendrik M. | Spiering, Wilko | Klungel, Olaf H. | Kumari, Meena | Whincup, Peter H. | Morrow, David A. | Braund, Peter S. | Hall, Alistair S. | Olsson, Anders G. | Doevendans, Pieter A. | Trip, Mieke D. | Tobin, Martin D. | Hamsten, Anders | Watkins, Hugh | Koenig, Wolfgang | Nicolaides, Andrew N. | Teupser, Daniel | Day, Ian N.M. | Carlquist, John F. | Gaunt, Tom R. | Ford, Ian | Sattar, Naveed | Tsimikas, Sotirios | Schwartz, Gregory G. | Lawlor, Debbie A. | Morris, Richard W. | Sandhu, Manjinder S. | Poledne, Rudolf | Maitland-van der Zee, Anke H. | Khaw, Kay-Tee | Keating, Brendan J. | van der Harst, Pim | Price, Jackie F. | Mehta, Shamir R. | Yusuf, Salim | Witteman, Jaqueline C.M. | Franco, Oscar H. | Jukema, J. Wouter | de Knijff, Peter | Tybjaerg-Hansen, Anne | Rader, Daniel J. | Farrall, Martin | Samani, Nilesh J. | Kivimaki, Mika | Fox, Keith A.A. | Humphries, Steve E. | Anderson, Jeffrey L. | Boekholdt, S. Matthijs | Palmer, Tom M. | Eriksson, Per | Paré, Guillaume | Hingorani, Aroon D. | Sabatine, Marc S. | Mallat, Ziad | Casas, Juan P. | Talmud, Philippa J.
Objectives
This study sought to investigate the role of secretory phospholipase A2 (sPLA2)-IIA in cardiovascular disease.
Background
Higher circulating levels of sPLA2-IIA mass or sPLA2 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 sPLA2 inhibitor (varespladib) was stopped prematurely for lack of efficacy.
Methods
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 sPLA2-IIA isoenzyme, as an instrumental variable.
Results
PLA2G2A rs11573156 C allele associated with lower circulating sPLA2-IIA mass (38% to 44%) and sPLA2 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 sPLA2-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.
Conclusions
Reducing sPLA2-IIA mass is unlikely to be a useful therapeutic goal for preventing cardiovascular events.
doi:10.1016/j.jacc.2013.06.044
PMCID: PMC3826105  PMID: 23916927
cardiovascular diseases; drug development; epidemiology; genetics; Mendelian randomization; ACS, acute coronary syndrome(s); CI, confidence interval; LDL-C, low-density lipoprotein cholesterol; MI, myocardial infarction; MVE, major vascular events; OR, odds ratio; RCT, randomized clinical trial; SNP, single-nucleotide polymorphism; sPLA2, secretory phospholipase A2
20.  From zebrafish heart jogging genes to mouse and human orthologs: using Gene Ontology to investigate mammalian heart development. 
F1000Research  2013;2:242.
For the majority of organs in developing vertebrate embryos, left-right asymmetry is controlled by a ciliated region; the left-right organizer node in the mouse and human, and the Kuppfer’s vesicle in the zebrafish. In the zebrafish, laterality cues from the Kuppfer’s vesicle determine asymmetry in the developing heart, the direction of ‘heart jogging’ and the direction of ‘heart looping’.  ‘Heart jogging’ is the term given to the process by which the symmetrical zebrafish heart tube is displaced relative to the dorsal midline, with a leftward ‘jog’. Heart jogging is not considered to occur in mammals, although a leftward shift of the developing mouse caudal heart does occur prior to looping, which may be analogous to zebrafish heart jogging. Previous studies have characterized 30 genes involved in zebrafish heart jogging, the majority of which have well defined orthologs in mouse and human and many of these orthologs have been associated with early mammalian heart development. 
 
We undertook manual curation of a specific set of genes associated with heart development and we describe the use of Gene Ontology term enrichment analyses to examine the cellular processes associated with heart jogging.  We found that the human, mouse and zebrafish ‘heart jogging orthologs’ are involved in similar organ developmental processes across the three species, such as heart, kidney and nervous system development, as well as more specific cellular processes such as cilium development and function. The results of these analyses are consistent with a role for cilia in the determination of left-right asymmetry of many internal organs, in addition to their known role in zebrafish heart jogging. 
 
This study highlights the importance of model organisms in the study of human heart development, and emphasises both the conservation and divergence of developmental processes across vertebrates, as well as the limitations of this approach.
doi:10.12688/f1000research.2-242.v1
PMCID: PMC3931453  PMID: 24627794
22.  Population Genomics of Cardiometabolic Traits: Design of the University College London-London School of Hygiene and Tropical Medicine-Edinburgh-Bristol (UCLEB) Consortium 
PLoS ONE  2013;8(8):e71345.
Substantial advances have been made in identifying common genetic variants influencing cardiometabolic traits and disease outcomes through genome wide association studies. Nevertheless, gaps in knowledge remain and new questions have arisen regarding the population relevance, mechanisms, and applications for healthcare. Using a new high-resolution custom single nucleotide polymorphism (SNP) array (Metabochip) incorporating dense coverage of genomic regions linked to cardiometabolic disease, the University College-London School-Edinburgh-Bristol (UCLEB) consortium of highly-phenotyped population-based prospective studies, aims to: (1) fine map functionally relevant SNPs; (2) precisely estimate individual absolute and population attributable risks based on individual SNPs and their combination; (3) investigate mechanisms leading to altered risk factor profiles and CVD events; and (4) use Mendelian randomisation to undertake studies of the causal role in CVD of a range of cardiovascular biomarkers to inform public health policy and help develop new preventative therapies.
doi:10.1371/journal.pone.0071345
PMCID: PMC3748096  PMID: 23977022
23.  A gene-centric study of common carotid artery remodelling 
Atherosclerosis  2013;226(2):440-446.
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 × 10−8). A proxy SNP (rs4916251, R2 = 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 × 10−3, I2 = 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.
Highlights
► In the IMPROVE study (n > 3000) variants at 1q24.3 were strongly associated with larger carotid diameters. ► The lead variant was associated with Abdominal Aortic Aneurysm (AAA) in meta-analysis of 5 studies (n > 50,000). ► Variants at 1q24.3 appear to be associated with vascular remodelling and risk of AAA.
doi:10.1016/j.atherosclerosis.2012.11.002
PMCID: PMC3573227  PMID: 23246012
Abdominal aortic aneurysm; Genome-wide association studies; Vascular remodelling; Carotid artery
24.  Use of Allele-Specific FAIRE to Determine Functional Regulatory Polymorphism Using Large-Scale Genotyping Arrays 
PLoS Genetics  2012;8(8):e1002908.
Following the widespread use of genome-wide association studies (GWAS), focus is turning towards identification of causal variants rather than simply genetic markers of diseases and traits. As a step towards a high-throughput method to identify genome-wide, non-coding, functional regulatory variants, we describe the technique of allele-specific FAIRE, utilising large-scale genotyping technology (FAIRE-gen) to determine allelic effects on chromatin accessibility and regulatory potential. FAIRE-gen was explored using lymphoblastoid cells and the 50,000 SNP Illumina CVD BeadChip. The technique identified an allele-specific regulatory polymorphism within NR1H3 (coding for LXR-α), rs7120118, coinciding with a previously GWAS-identified SNP for HDL-C levels. This finding was confirmed using FAIRE-gen with the 200,000 SNP Illumina Metabochip and verified with the established method of TaqMan allelic discrimination. Examination of this SNP in two prospective Caucasian cohorts comprising 15,000 individuals confirmed the association with HDL-C levels (combined beta = 0.016; p = 0.0006), and analysis of gene expression identified an allelic association with LXR-α expression in heart tissue. Using increasingly comprehensive genotyping chips and distinct tissues for examination, FAIRE-gen has the potential to aid the identification of many causal SNPs associated with disease from GWAS.
Author Summary
The identification of genetic variants associated with complex diseases has rapidly grown through lowering costs of genome sequencing and the use of large-scale genotyping chips based on this sequencing data. There have not been corresponding advances in the identification of causal genetic variants compared to variants simply associated with diseases or traits. Most of these causal variants are thought to be located not within regions coding for proteins, but within genomic regions that regulate the level of protein. We have combined the use of large-scale gene chips with functional analysis, to determine regions of the genome that confer a greater potential for controlling gene regulation dependent on the genotype of that individual. Combining this data with population data and gene expression data, we identify a potential causal variant that alters regulation of LXR-α, a key mediator in lipid metabolism, and show that this variant is associated with HDL-C levels. This methodology provides a model for future analyses to identify further causal variants for disease.
doi:10.1371/journal.pgen.1002908
PMCID: PMC3420950  PMID: 22916038
25.  Functional Analysis of Two PLA2G2A Variants Associated with Secretory Phospholipase A2-IIA Levels 
PLoS ONE  2012;7(7):e41139.
Background
Secretory phospholipase A2 group IIA (sPLA2-IIA) has been identified as a biomarker of atherosclerosis in observational and animal studies. The protein is encoded by the PLA2G2A gene and the aim of this study was to test the functionality of two PLA2G2A non-coding SNPs, rs11573156 C>G and rs3767221 T>G where the rare alleles have been previously associated with higher and lower sPLA2-IIA levels respectively.
Methodology/Principal Findings
Luciferase assays, electrophoretic mobility shift assays (EMSA), and RNA expression by RT-PCR were used to examine allelic differences. For rs3767221 the G allele showed ∼55% lower luciferase activity compared to the T allele (T = 62.1 (95% CI 59.1 to 65.1) G = 27.8 (95% CI 25.0 to 30.6), p = 1.22×10−35, and stronger EMSA binding of a nuclear protein compared to the T-allele. For rs11573156 C >G there were no luciferase or EMSA allelic differences seen. In lymphocyte cell RNA, from individuals of known rs11573156 genotype, there was no allelic RNA expression difference for exons 5 and 6, but G allele carriers (n = 7) showed a trend to lower exon 1–2 expression compared to CC individuals. To take this further, in the ASAP study (n = 223), an rs11573156 proxy (r2 = 0.91) showed ∼25% higher liver expression of PLA2G2A (1.67×10−17) associated with the G allele. However, considering exon specific expression, the association was greatly reduced for exon 2 (4.5×10−5) compared to exons 3–6 (10−10 to 10−20), suggesting rs11573156 G allele-specific exon 2 skipping.
Conclusion
Both SNPs are functional and provide useful tools for Mendelian Randomisation to determine whether the relationship between sPLA2-IIA and coronary heart disease is causal.
doi:10.1371/journal.pone.0041139
PMCID: PMC3412631  PMID: 22879865

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