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1.  Genome-Wide Association Study of Metabolic Traits Reveals Novel Gene-Metabolite-Disease Links 
PLoS Genetics  2014;10(2):e1004132.
Metabolic traits are molecular phenotypes that can drive clinical phenotypes and may predict disease progression. Here, we report results from a metabolome- and genome-wide association study on 1H-NMR urine metabolic profiles. The study was conducted within an untargeted approach, employing a novel method for compound identification. From our discovery cohort of 835 Caucasian individuals who participated in the CoLaus study, we identified 139 suggestively significant (P<5×10−8) and independent associations between single nucleotide polymorphisms (SNP) and metabolome features. Fifty-six of these associations replicated in the TasteSensomics cohort, comprising 601 individuals from São Paulo of vastly diverse ethnic background. They correspond to eleven gene-metabolite associations, six of which had been previously identified in the urine metabolome and three in the serum metabolome. Our key novel findings are the associations of two SNPs with NMR spectral signatures pointing to fucose (rs492602, P = 6.9×10−44) and lysine (rs8101881, P = 1.2×10−33), respectively. Fine-mapping of the first locus pinpointed the FUT2 gene, which encodes a fucosyltransferase enzyme and has previously been associated with Crohn's disease. This implicates fucose as a potential prognostic disease marker, for which there is already published evidence from a mouse model. The second SNP lies within the SLC7A9 gene, rare mutations of which have been linked to severe kidney damage. The replication of previous associations and our new discoveries demonstrate the potential of untargeted metabolomics GWAS to robustly identify molecular disease markers.
Author Summary
The concentrations of small molecules known as metabolites, are subject to tight regulation in all organisms. Collectively, the metabolite concentrations make up the metabolome, which differs amongst individuals as a function of their environment and genetic makeup. In our study, we have further developed an untargeted approach to identify genetic factors affecting human metabolism. In this approach, we first identify all genetic variants that correlate with any of the measured metabolome features in a large set of individuals. For these variants, we then compute a profile of significance for association with all features, generating a signature that facilitates the expert or computational identification of the metabolite whose concentration is most likely affected by the genetic variant at hand. Our study replicated many of the previously reported genetically driven variations in human metabolism and revealed two new striking examples of genetic variations with a sizeable effect on the urine metabolome. Interestingly, in these two gene-metabolite pairs both the gene and the affected metabolite are related to human diseases – Crohn's disease in the first case, and kidney disease in the second. This highlights the connection between genetic predispositions, affected metabolites, and human health.
doi:10.1371/journal.pgen.1004132
PMCID: PMC3930510  PMID: 24586186
2.  A Comparison of Bayesian and Frequentist Approaches to Incorporating External Information for the Prediction of Prostate Cancer Risk 
Genetic epidemiology  2012;36(1):71-83.
We present the most comprehensive comparison to date of the predictive benefit of genetics in addition to currently used clinical variables, using genotype data for 33 single-nucleotide polymorphisms (SNPs) in 1,547 Caucasian men from the placebo arm of the REduction by DUtasteride of prostate Cancer Events (REDUCE®) trial. Moreover, we conducted a detailed comparison of three techniques for incorporating genetics into clinical risk prediction. The first method was a standard logistic regression model, which included separate terms for the clinical covariates and for each of the genetic markers. This approach ignores a substantial amount of external information concerning effect sizes for these Genome Wide Association Study (GWAS)-replicated SNPs. The second and third methods investigated two possible approaches to incorporating meta-analysed external SNP effect estimates – one via a weighted PCa ‘risk’ score based solely on the meta analysis estimates, and the other incorporating both the current and prior data via informative priors in a Bayesian logistic regression model. All methods demonstrated a slight improvement in predictive performance upon incorporation of genetics. The two methods that incorporated external information showed the greatest receiver-operating-characteristic AUCs increase from 0.61 to 0.64. The value of our methods comparison is likely to lie in observations of performance similarities, rather than difference, between three approaches of very different resource requirements. The two methods that included external information performed best, but only marginally despite substantial differences in complexity.
doi:10.1002/gepi.21600
PMCID: PMC3791431  PMID: 22890972
prostate cancer; genetic clinical risk prediction; genetic scores; Bayesian logistic regression; predictive assessment
3.  Deep sequencing of the LRRK2 gene in 14,002 individuals reveals evidence of purifying selection and independent origin of the p.Arg1628Pro mutation in Europe 
Human Mutation  2012;33(7):1087-1098.
Genetic variation in LRRK2 predisposes to Parkinson disease (PD), which underpins its development as a therapeutic target. Here, we aimed to identify novel genotype-phenotype associations that might support developing LRRK2 therapies for other conditions. We sequenced the 51 exons of LRRK2 in cases comprising 12 common diseases (n = 9,582), and in 4,420 population controls. We identified 739 single nucleotide variants (SNVs), 62% of which were observed in only one person, including 316 novel exonic variants. We found evidence of purifying selection for the LRRK2 gene and a trend suggesting that this is more pronounced in the central (ROC-COR-kinase) core protein domains of LRRK2 than the flanking domains. Population genetic analyses revealed that LRRK2 is not especially polymorphic or differentiated in comparison to 201 other drug target genes. Amongst Europeans, we identified 17 carriers (0.13%) of pathogenic LRRK2 mutations that were not significantly enriched within any disease or in those reporting a family history of PD. Analysis of pathogenic mutations within Europe reveals that the p.Arg1628Pro (c4883G>C) mutation arose independently in Europe and Asia. Taken together, these findings demonstrate how targeted deep sequencing can help to reveal fundamental characteristics of clinically important loci.
doi:10.1002/humu.22075
PMCID: PMC3370131  PMID: 22415848
LRRK2; Deep sequencing; novel variants; evolution; population genetics; genotype-phenotype associations
4.  Deep Resequencing Unveils Genetic Architecture of ADIPOQ and Identifies a Novel Low-Frequency Variant Strongly Associated With Adiponectin Variation 
Diabetes  2012;61(5):1297-1301.
Increased adiponectin levels have been shown to be associated with a lower risk of type 2 diabetes. To understand the relations between genetic variation at the adiponectin-encoding gene, ADIPOQ, and adiponectin levels, and subsequently its role in disease, we conducted a deep resequencing experiment of ADIPOQ in 14,002 subjects, including 12,514 Europeans, 594 African Americans, and 567 Indian Asians. We identified 296 single nucleotide polymorphisms (SNPs), including 30 amino acid changes, and carried out association analyses in a subset of 3,665 subjects from two independent studies. We confirmed multiple genome-wide association study findings and identified a novel association between a low-frequency SNP (rs17366653) and adiponectin levels (P = 2.2E–17). We show that seven SNPs exert independent effects on adiponectin levels. Together, they explained 6% of adiponectin variation in our samples. We subsequently assessed association between these SNPs and type 2 diabetes in the Genetics of Diabetes Audit and Research in Tayside Scotland (GO-DARTS) study, comprised of 5,145 case and 6,374 control subjects. No evidence of association with type 2 diabetes was found, but we were also unable to exclude the possibility of substantial effects (e.g., odds ratio 95% CI for rs7366653 [0.91–1.58]). Further investigation by large-scale and well-powered Mendelian randomization studies is warranted.
doi:10.2337/db11-0985
PMCID: PMC3331741  PMID: 22403302
5.  Plasma lipoprotein-associated phospholipase A2 activity in Alzheimer's disease, amnestic mild cognitive impairment, and cognitively healthy elderly subjects: a cross-sectional study 
Introduction
Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a circulating enzyme with pro-inflammatory and oxidative activities associated with cardiovascular disease and ischemic stroke. While high plasma Lp-PLA2 activity was reported as a risk factor for dementia in the Rotterdam study, no association between Lp-PLA2 mass and dementia or Alzheimer's disease (AD) was detected in the Framingham study. The objectives of the current study were to explore the relationship of plasma Lp-PLA2 activity with cognitive diagnoses (AD, amnestic mild cognitive impairment (aMCI), and cognitively healthy subjects), cardiovascular markers, cerebrospinal fluid (CSF) markers of AD, and apolipoprotein E (APOE) genotype.
Methods
Subjects with mild AD (n = 78) and aMCI (n = 59) were recruited from the Memory Clinic, University Hospital, Basel, Switzerland; cognitively healthy subjects (n = 66) were recruited from the community. Subjects underwent standardised medical, neurological, neuropsychological, imaging, genetic, blood and CSF evaluation. Differences in Lp-PLA2 activity between the cognitive diagnosis groups were tested with ANOVA and in multiple linear regression models with adjustment for covariates. Associations between Lp-PLA2 and markers of cardiovascular disease and AD were explored with Spearman's correlation coefficients.
Results
There was no significant difference in plasma Lp-PLA2 activity between AD (197.1 (standard deviation, SD 38.4) nmol/min/ml) and controls (195.4 (SD 41.9)). Gender, statin use and low-density lipoprotein cholesterol (LDL) were independently associated with Lp-PLA2 activity in multiple regression models. Lp-PLA2 activity was correlated with LDL and inversely correlated with high-density lipoprotein (HDL). AD subjects with APOE-ε4 had higher Lp-PLA2 activity (207.9 (SD 41.2)) than AD subjects lacking APOE-ε4 (181.6 (SD 26.0), P = 0.003) although this was attenuated by adjustment for LDL (P = 0.09). No strong correlations were detected for Lp-PLA2 activity and CSF markers of AD.
Conclusion
Plasma Lp-PLA2 was not associated with a diagnosis of AD or aMCI in this cross-sectional study. The main clinical correlates of Lp-PLA2 activity in AD, aMCI and cognitively healthy subjects were variables associated with lipid metabolism.
doi:10.1186/alzrt154
PMCID: PMC3580460  PMID: 23217243
6.  Genome-wide association study identifies six new loci influencing pulse pressure and mean arterial pressure 
Wain, Louise V | Verwoert, Germaine C | O’Reilly, Paul F | Shi, Gang | Johnson, Toby | Johnson, Andrew D | Bochud, Murielle | Rice, Kenneth M | Henneman, Peter | Smith, Albert V | Ehret, Georg B | Amin, Najaf | Larson, Martin G | Mooser, Vincent | Hadley, David | Dörr, Marcus | Bis, Joshua C | Aspelund, Thor | Esko, Tõnu | Janssens, A Cecile JW | Zhao, Jing Hua | Heath, Simon | Laan, Maris | Fu, Jingyuan | Pistis, Giorgio | Luan, Jian’an | Arora, Pankaj | Lucas, Gavin | Pirastu, Nicola | Pichler, Irene | Jackson, Anne U | Webster, Rebecca J | Zhang, Feng | Peden, John F | Schmidt, Helena | Tanaka, Toshiko | Campbell, Harry | Igl, Wilmar | Milaneschi, Yuri | Hotteng, Jouke-Jan | Vitart, Veronique | Chasman, Daniel I | Trompet, Stella | Bragg-Gresham, Jennifer L | Alizadeh, Behrooz Z | Chambers, John C | Guo, Xiuqing | Lehtimäki, Terho | Kühnel, Brigitte | Lopez, Lorna M | Polašek, Ozren | Boban, Mladen | Nelson, Christopher P | Morrison, Alanna C | Pihur, Vasyl | Ganesh, Santhi K | Hofman, Albert | Kundu, Suman | Mattace-Raso, Francesco US | Rivadeneira, Fernando | Sijbrands, Eric JG | Uitterlinden, Andre G | Hwang, Shih-Jen | Vasan, Ramachandran S | Wang, Thomas J | Bergmann, Sven | Vollenweider, Peter | Waeber, Gérard | Laitinen, Jaana | Pouta, Anneli | Zitting, Paavo | McArdle, Wendy L | Kroemer, Heyo K | Völker, Uwe | Völzke, Henry | Glazer, Nicole L | Taylor, Kent D | Harris, Tamara B | Alavere, Helene | Haller, Toomas | Keis, Aime | Tammesoo, Mari-Liis | Aulchenko, Yurii | Barroso, Inês | Khaw, Kay-Tee | Galan, Pilar | Hercberg, Serge | Lathrop, Mark | Eyheramendy, Susana | Org, Elin | Sõber, Siim | Lu, Xiaowen | Nolte, Ilja M | Penninx, Brenda W | Corre, Tanguy | Masciullo, Corrado | Sala, Cinzia | Groop, Leif | Voight, Benjamin F | Melander, Olle | O’Donnell, Christopher J | Salomaa, Veikko | d’Adamo, Adamo Pio | Fabretto, Antonella | Faletra, Flavio | Ulivi, Sheila | Del Greco, M Fabiola | Facheris, Maurizio | Collins, Francis S | Bergman, Richard N | Beilby, John P | Hung, Joseph | Musk, A William | Mangino, Massimo | Shin, So-Youn | Soranzo, Nicole | Watkins, Hugh | Goel, Anuj | Hamsten, Anders | Gider, Pierre | Loitfelder, Marisa | Zeginigg, Marion | Hernandez, Dena | Najjar, Samer S | Navarro, Pau | Wild, Sarah H | Corsi, Anna Maria | Singleton, Andrew | de Geus, Eco JC | Willemsen, Gonneke | Parker, Alex N | Rose, Lynda M | Buckley, Brendan | Stott, David | Orru, Marco | Uda, Manuela | van der Klauw, Melanie M | Zhang, Weihua | Li, Xinzhong | Scott, James | Chen, Yii-Der Ida | Burke, Gregory L | Kähönen, Mika | Viikari, Jorma | Döring, Angela | Meitinger, Thomas | Davies, Gail | Starr, John M | Emilsson, Valur | Plump, Andrew | Lindeman, Jan H | ’t Hoen, Peter AC | König, Inke R | Felix, Janine F | Clarke, Robert | Hopewell, Jemma C | Ongen, Halit | Breteler, Monique | Debette, Stéphanie | DeStefano, Anita L | Fornage, Myriam | Mitchell, Gary F | Smith, Nicholas L | Holm, Hilma | Stefansson, Kari | Thorleifsson, Gudmar | Thorsteinsdottir, Unnur | Samani, Nilesh J | Preuss, Michael | Rudan, Igor | Hayward, Caroline | Deary, Ian J | Wichmann, H-Erich | Raitakari, Olli T | Palmas, Walter | Kooner, Jaspal S | Stolk, Ronald P | Jukema, J Wouter | Wright, Alan F | Boomsma, Dorret I | Bandinelli, Stefania | Gyllensten, Ulf B | Wilson, James F | Ferrucci, Luigi | Schmidt, Reinhold | Farrall, Martin | Spector, Tim D | Palmer, Lyle J | Tuomilehto, Jaakko | Pfeufer, Arne | Gasparini, Paolo | Siscovick, David | Altshuler, David | Loos, Ruth JF | Toniolo, Daniela | Snieder, Harold | Gieger, Christian | Meneton, Pierre | Wareham, Nicholas J | Oostra, Ben A | Metspalu, Andres | Launer, Lenore | Rettig, Rainer | Strachan, David P | Beckmann, Jacques S | Witteman, Jacqueline CM | Erdmann, Jeanette | van Dijk, Ko Willems | Boerwinkle, Eric | Boehnke, Michael | Ridker, Paul M | Jarvelin, Marjo-Riitta | Chakravarti, Aravinda | Abecasis, Goncalo R | Gudnason, Vilmundur | Newton-Cheh, Christopher | Levy, Daniel | Munroe, Patricia B | Psaty, Bruce M | Caulfield, Mark J | Rao, Dabeeru C | Tobin, Martin D | Elliott, Paul | van Duijn, Cornelia M
Nature genetics  2011;43(10):1005-1011.
Numerous genetic loci influence systolic blood pressure (SBP) and diastolic blood pressure (DBP) in Europeans 1-3. We now report genome-wide association studies of pulse pressure (PP) and mean arterial pressure (MAP). In discovery (N=74,064) and follow-up studies (N=48,607), we identified at genome-wide significance (P= 2.7×10-8 to P=2.3×10-13) four novel PP loci (at 4q12 near CHIC2/PDGFRAI, 7q22.3 near PIK3CG, 8q24.12 in NOV, 11q24.3 near ADAMTS-8), two novel MAP loci (3p21.31 in MAP4, 10q25.3 near ADRB1) and one locus associated with both traits (2q24.3 near FIGN) which has recently been associated with SBP in east Asians. For three of the novel PP signals, the estimated effect for SBP was opposite to that for DBP, in contrast to the majority of common SBP- and DBP-associated variants which show concordant effects on both traits. These findings indicate novel genetic mechanisms underlying blood pressure variation, including pathways that may differentially influence SBP and DBP.
doi:10.1038/ng.922
PMCID: PMC3445021  PMID: 21909110
7.  Genome-wide association study identifies two loci strongly affecting transferrin glycosylation 
Human Molecular Genetics  2011;20(18):3710-3717.
Polysaccharide sidechains attached to proteins play important roles in cell–cell and receptor–ligand interactions. Variation in the carbohydrate component has been extensively studied for the iron transport protein transferrin, because serum levels of the transferrin isoforms asialotransferrin + disialotransferrin (carbohydrate-deficient transferrin, CDT) are used as biomarkers of excessive alcohol intake. We conducted a genome-wide association study to assess whether genetic factors affect CDT concentration in serum. CDT was measured in three population-based studies: one in Switzerland (CoLaus study, n = 5181) and two in Australia (n = 1509, n = 775). The first cohort was used as the discovery panel and the latter ones served as replication. Genome-wide single-nucleotide polymorphism (SNP) typing data were used to identify loci with significant associations with CDT as a percentage of total transferrin (CDT%). The top three SNPs in the discovery panel (rs2749097 near PGM1 on chromosome 1, and missense polymorphisms rs1049296, rs1799899 in TF on chromosome 3) were successfully replicated , yielding genome-wide significant combined association with CDT% (P = 1.9 × 10−9, 4 × 10−39, 5.5 × 10−43, respectively) and explain 5.8% of the variation in CDT%. These allelic effects are postulated to be caused by variation in availability of glucose-1-phosphate as a precursor of the glycan (PGM1), and variation in transferrin (TF) structure.
doi:10.1093/hmg/ddr272
PMCID: PMC3159549  PMID: 21665994
8.  Plasma HDL cholesterol and risk of myocardial infarction: a mendelian randomisation study 
Voight, Benjamin F | Peloso, Gina M | Orho-Melander, Marju | Frikke-Schmidt, Ruth | Barbalic, Maja | Jensen, Majken K | Hindy, George | Hólm, Hilma | Ding, Eric L | Johnson, Toby | Schunkert, Heribert | Samani, Nilesh J | Clarke, Robert | Hopewell, Jemma C | Thompson, John F | Li, Mingyao | Thorleifsson, Gudmar | Newton-Cheh, Christopher | Musunuru, Kiran | Pirruccello, James P | Saleheen, Danish | Chen, Li | Stewart, Alexandre FR | Schillert, Arne | Thorsteinsdottir, Unnur | Thorgeirsson, Gudmundur | Anand, Sonia | Engert, James C | Morgan, Thomas | Spertus, John | Stoll, Monika | Berger, Klaus | Martinelli, Nicola | Girelli, Domenico | McKeown, Pascal P | Patterson, Christopher C | Epstein, Stephen E | Devaney, Joseph | Burnett, Mary-Susan | Mooser, Vincent | Ripatti, Samuli | Surakka, Ida | Nieminen, Markku S | Sinisalo, Juha | Lokki, Marja-Liisa | Perola, Markus | Havulinna, Aki | de Faire, Ulf | Gigante, Bruna | Ingelsson, Erik | Zeller, Tanja | Wild, Philipp | de Bakker, Paul I W | Klungel, Olaf H | Maitland-van der Zee, Anke-Hilse | Peters, Bas J M | de Boer, Anthonius | Grobbee, Diederick E | Kamphuisen, Pieter W | Deneer, Vera H M | Elbers, Clara C | Onland-Moret, N Charlotte | Hofker, Marten H | Wijmenga, Cisca | Verschuren, WM Monique | Boer, Jolanda MA | van der Schouw, Yvonne T | Rasheed, Asif | Frossard, Philippe | Demissie, Serkalem | Willer, Cristen | Do, Ron | Ordovas, Jose M | Abecasis, Gonçalo R | Boehnke, Michael | Mohlke, Karen L | Daly, Mark J | Guiducci, Candace | Burtt, Noël P | Surti, Aarti | Gonzalez, Elena | Purcell, Shaun | Gabriel, Stacey | Marrugat, Jaume | Peden, John | Erdmann, Jeanette | Diemert, Patrick | Willenborg, Christina | König, Inke R | Fischer, Marcus | Hengstenberg, Christian | Ziegler, Andreas | Buysschaert, Ian | Lambrechts, Diether | Van de Werf, Frans | Fox, Keith A | El Mokhtari, Nour Eddine | Rubin, Diana | Schrezenmeir, Jürgen | Schreiber, Stefan | Schäfer, Arne | Danesh, John | Blankenberg, Stefan | Roberts, Robert | McPherson, Ruth | Watkins, Hugh | Hall, Alistair S | Overvad, Kim | Rimm, Eric | Boerwinkle, Eric | Tybjaerg-Hansen, Anne | Cupples, L Adrienne | Reilly, Muredach P | Melander, Olle | Mannucci, Pier M | Ardissino, Diego | Siscovick, David | Elosua, Roberto | Stefansson, Kari | O'Donnell, Christopher J | Salomaa, Veikko | Rader, Daniel J | Peltonen, Leena | Schwartz, Stephen M | Altshuler, David | Kathiresan, Sekar
Lancet  2012;380(9841):572-580.
Summary
Background
High plasma HDL cholesterol is associated with reduced risk of myocardial infarction, but whether this association is causal is unclear. Exploiting the fact that genotypes are randomly assigned at meiosis, are independent of non-genetic confounding, and are unmodified by disease processes, mendelian randomisation can be used to test the hypothesis that the association of a plasma biomarker with disease is causal.
Methods
We performed two mendelian randomisation analyses. First, we used as an instrument a single nucleotide polymorphism (SNP) in the endothelial lipase gene (LIPG Asn396Ser) and tested this SNP in 20 studies (20 913 myocardial infarction cases, 95 407 controls). Second, we used as an instrument a genetic score consisting of 14 common SNPs that exclusively associate with HDL cholesterol and tested this score in up to 12 482 cases of myocardial infarction and 41 331 controls. As a positive control, we also tested a genetic score of 13 common SNPs exclusively associated with LDL cholesterol.
Findings
Carriers of the LIPG 396Ser allele (2·6% frequency) had higher HDL cholesterol (0·14 mmol/L higher, p=8×10−13) but similar levels of other lipid and non-lipid risk factors for myocardial infarction compared with non-carriers. This difference in HDL cholesterol is expected to decrease risk of myocardial infarction by 13% (odds ratio [OR] 0·87, 95% CI 0·84–0·91). However, we noted that the 396Ser allele was not associated with risk of myocardial infarction (OR 0·99, 95% CI 0·88–1·11, p=0·85). From observational epidemiology, an increase of 1 SD in HDL cholesterol was associated with reduced risk of myocardial infarction (OR 0·62, 95% CI 0·58–0·66). However, a 1 SD increase in HDL cholesterol due to genetic score was not associated with risk of myocardial infarction (OR 0·93, 95% CI 0·68–1·26, p=0·63). For LDL cholesterol, the estimate from observational epidemiology (a 1 SD increase in LDL cholesterol associated with OR 1·54, 95% CI 1·45–1·63) was concordant with that from genetic score (OR 2·13, 95% CI 1·69–2·69, p=2×10−10).
Interpretation
Some genetic mechanisms that raise plasma HDL cholesterol do not seem to lower risk of myocardial infarction. These data challenge the concept that raising of plasma HDL cholesterol will uniformly translate into reductions in risk of myocardial infarction.
Funding
US National Institutes of Health, The Wellcome Trust, European Union, British Heart Foundation, and the German Federal Ministry of Education and Research.
doi:10.1016/S0140-6736(12)60312-2
PMCID: PMC3419820  PMID: 22607825
9.  Effects of particulate matter on inflammatory markers in the general adult population 
Background
Particulate air pollution is associated with increased risk of cardiovascular disease and stroke. Although the precise mechanisms underlying this association are still unclear, the induction of systemic inflammation following particle inhalation represents a plausible mechanistic pathway.
Methods
We used baseline data from the CoLaus Study including 6183 adult participants residing in Lausanne, Switzerland. We analyzed the association of short-term exposure to PM10 (on the day of examination visit) with continuous circulating serum levels of high-sensitive C-reactive protein (hs-CRP), interleukin 1-beta (IL-1β), interleukin 6 (IL-6), and tumor-necrosis-factor alpha (TNF-α) by robust linear regressions, controlling for potential confounding factors and assessing effect modification.
Results
In adjusted analyses, for every 10 μg/m3 elevation in PM10, IL-1ß increased by 0.034 (95 % confidence interval, 0.007-0.060) pg/mL, IL-6 by 0.036 (0.015-0.057) pg/mL, and TNF-α by 0.024 (0.013-0.035) pg/mL, whereas no significant association was found with hs-CRP levels.
Conclusions
Short-term exposure to PM10 was positively associated with higher levels of circulating IL-1ß, IL-6 and TNF-α in the adult general population. This positive association suggests a link between air pollution and cardiovascular risk, although further studies are needed to clarify the mechanistic pathway linking PM10 to cardiovascular risk.
doi:10.1186/1743-8977-9-24
PMCID: PMC3464812  PMID: 22769230
High-sensitive C-reactive protein (hs-CRP); Interleukin 1-beta (IL-1β); Interleukin 6 (IL-6); Tumor-necrosis-factor alpha (TNF-α); Air pollution
10.  Identification and validation of copy number variants using SNP genotyping arrays from a large clinical cohort 
BMC Genomics  2012;13:241.
Background
Genotypes obtained with commercial SNP arrays have been extensively used in many large case-control or population-based cohorts for SNP-based genome-wide association studies for a multitude of traits. Yet, these genotypes capture only a small fraction of the variance of the studied traits. Genomic structural variants (GSV) such as Copy Number Variation (CNV) may account for part of the missing heritability, but their comprehensive detection requires either next-generation arrays or sequencing. Sophisticated algorithms that infer CNVs by combining the intensities from SNP-probes for the two alleles can already be used to extract a partial view of such GSV from existing data sets.
Results
Here we present several advances to facilitate the latter approach. First, we introduce a novel CNV detection method based on a Gaussian Mixture Model. Second, we propose a new algorithm, PCA merge, for combining copy-number profiles from many individuals into consensus regions. We applied both our new methods as well as existing ones to data from 5612 individuals from the CoLaus study who were genotyped on Affymetrix 500K arrays. We developed a number of procedures in order to evaluate the performance of the different methods. This includes comparison with previously published CNVs as well as using a replication sample of 239 individuals, genotyped with Illumina 550K arrays. We also established a new evaluation procedure that employs the fact that related individuals are expected to share their CNVs more frequently than randomly selected individuals. The ability to detect both rare and common CNVs provides a valuable resource that will facilitate association studies exploring potential phenotypic associations with CNVs.
Conclusion
Our new methodologies for CNV detection and their evaluation will help in extracting additional information from the large amount of SNP-genotyping data on various cohorts and use this to explore structural variants and their impact on complex traits.
doi:10.1186/1471-2164-13-241
PMCID: PMC3464625  PMID: 22702538
11.  Six Novel Susceptibility Loci for Early-Onset Androgenetic Alopecia and Their Unexpected Association with Common Diseases 
PLoS Genetics  2012;8(5):e1002746.
Androgenetic alopecia (AGA) is a highly heritable condition and the most common form of hair loss in humans. Susceptibility loci have been described on the X chromosome and chromosome 20, but these loci explain a minority of its heritable variance. We conducted a large-scale meta-analysis of seven genome-wide association studies for early-onset AGA in 12,806 individuals of European ancestry. While replicating the two AGA loci on the X chromosome and chromosome 20, six novel susceptibility loci reached genome-wide significance (p = 2.62×10−9–1.01×10−12). Unexpectedly, we identified a risk allele at 17q21.31 that was recently associated with Parkinson's disease (PD) at a genome-wide significant level. We then tested the association between early-onset AGA and the risk of PD in a cross-sectional analysis of 568 PD cases and 7,664 controls. Early-onset AGA cases had significantly increased odds of subsequent PD (OR = 1.28, 95% confidence interval: 1.06–1.55, p = 8.9×10−3). Further, the AGA susceptibility alleles at the 17q21.31 locus are on the H1 haplotype, which is under negative selection in Europeans and has been linked to decreased fertility. Combining the risk alleles of six novel and two established susceptibility loci, we created a genotype risk score and tested its association with AGA in an additional sample. Individuals in the highest risk quartile of a genotype score had an approximately six-fold increased risk of early-onset AGA [odds ratio (OR) = 5.78, p = 1.4×10−88]. Our results highlight unexpected associations between early-onset AGA, Parkinson's disease, and decreased fertility, providing important insights into the pathophysiology of these conditions.
Author Summary
While most genome-wide association studies (GWAS) focus on the identification of susceptibility loci for a specific disease, this hypothesis-free approach also enables the identification of unexpected associations between different diseases by taking advantage of the previously published GWAS associations. Androgenetic Alopecia (AGA, also known as male pattern baldness) is the most common type of hair loss in humans. Parkinson's disease is reported to occur more commonly in men than in women; however, there are no studies investigating the link between AGA and Parkinson's disease. Here, we show that a specific genetic locus, chromosome 17q21.31, which is associated with Parkinson's disease, is also a susceptibility locus for early-onset AGA. We further investigate the association between early-onset AGA and Parkinson's disease, irrespective of genotype, directly in a large-scale web-based study. We find that men with early-onset AGA have 28% higher risk of developing Parkinson's disease. The early-onset AGA locus on chromosome 17q21.31 has also been linked to decreased fertility previously. Future studies of this locus may implicate novel biological pathways affecting these three conditions.
doi:10.1371/journal.pgen.1002746
PMCID: PMC3364959  PMID: 22693459
12.  Novel Loci for Adiponectin Levels and Their Influence on Type 2 Diabetes and Metabolic Traits: A Multi-Ethnic Meta-Analysis of 45,891 Individuals 
Dastani, Zari | Hivert, Marie-France | Timpson, Nicholas | Perry, John R. B. | Yuan, Xin | Scott, Robert A. | Henneman, Peter | Heid, Iris M. | Kizer, Jorge R. | Lyytikäinen, Leo-Pekka | Fuchsberger, Christian | Tanaka, Toshiko | Morris, Andrew P. | Small, Kerrin | Isaacs, Aaron | Beekman, Marian | Coassin, Stefan | Lohman, Kurt | Qi, Lu | Kanoni, Stavroula | Pankow, James S. | Uh, Hae-Won | Wu, Ying | Bidulescu, Aurelian | Rasmussen-Torvik, Laura J. | Greenwood, Celia M. T. | Ladouceur, Martin | Grimsby, Jonna | Manning, Alisa K. | Liu, Ching-Ti | Kooner, Jaspal | Mooser, Vincent E. | Vollenweider, Peter | Kapur, Karen A. | Chambers, John | Wareham, Nicholas J. | Langenberg, Claudia | Frants, Rune | Willems-vanDijk, Ko | Oostra, Ben A. | Willems, Sara M. | Lamina, Claudia | Winkler, Thomas W. | Psaty, Bruce M. | Tracy, Russell P. | Brody, Jennifer | Chen, Ida | Viikari, Jorma | Kähönen, Mika | Pramstaller, Peter P. | Evans, David M. | St. Pourcain, Beate | Sattar, Naveed | Wood, Andrew R. | Bandinelli, Stefania | Carlson, Olga D. | Egan, Josephine M. | Böhringer, Stefan | van Heemst, Diana | Kedenko, Lyudmyla | Kristiansson, Kati | Nuotio, Marja-Liisa | Loo, Britt-Marie | Harris, Tamara | Garcia, Melissa | Kanaya, Alka | Haun, Margot | Klopp, Norman | Wichmann, H.-Erich | Deloukas, Panos | Katsareli, Efi | Couper, David J. | Duncan, Bruce B. | Kloppenburg, Margreet | Adair, Linda S. | Borja, Judith B. | Wilson, James G. | Musani, Solomon | Guo, Xiuqing | Johnson, Toby | Semple, Robert | Teslovich, Tanya M. | Allison, Matthew A. | Redline, Susan | Buxbaum, Sarah G. | Mohlke, Karen L. | Meulenbelt, Ingrid | Ballantyne, Christie M. | Dedoussis, George V. | Hu, Frank B. | Liu, Yongmei | Paulweber, Bernhard | Spector, Timothy D. | Slagboom, P. Eline | Ferrucci, Luigi | Jula, Antti | Perola, Markus | Raitakari, Olli | Florez, Jose C. | Salomaa, Veikko | Eriksson, Johan G. | Frayling, Timothy M. | Hicks, Andrew A. | Lehtimäki, Terho | Smith, George Davey | Siscovick, David S. | Kronenberg, Florian | van Duijn, Cornelia | Loos, Ruth J. F. | Waterworth, Dawn M. | Meigs, James B. | Dupuis, Josee | Richards, J. Brent | Visscher, Peter M.
PLoS Genetics  2012;8(3):e1002607.
Circulating levels of adiponectin, a hormone produced predominantly by adipocytes, are highly heritable and are inversely associated with type 2 diabetes mellitus (T2D) and other metabolic traits. We conducted a meta-analysis of genome-wide association studies in 39,883 individuals of European ancestry to identify genes associated with metabolic disease. We identified 8 novel loci associated with adiponectin levels and confirmed 2 previously reported loci (P = 4.5×10−8–1.2×10−43). Using a novel method to combine data across ethnicities (N = 4,232 African Americans, N = 1,776 Asians, and N = 29,347 Europeans), we identified two additional novel loci. Expression analyses of 436 human adipocyte samples revealed that mRNA levels of 18 genes at candidate regions were associated with adiponectin concentrations after accounting for multiple testing (p<3×10−4). We next developed a multi-SNP genotypic risk score to test the association of adiponectin decreasing risk alleles on metabolic traits and diseases using consortia-level meta-analytic data. This risk score was associated with increased risk of T2D (p = 4.3×10−3, n = 22,044), increased triglycerides (p = 2.6×10−14, n = 93,440), increased waist-to-hip ratio (p = 1.8×10−5, n = 77,167), increased glucose two hours post oral glucose tolerance testing (p = 4.4×10−3, n = 15,234), increased fasting insulin (p = 0.015, n = 48,238), but with lower in HDL-cholesterol concentrations (p = 4.5×10−13, n = 96,748) and decreased BMI (p = 1.4×10−4, n = 121,335). These findings identify novel genetic determinants of adiponectin levels, which, taken together, influence risk of T2D and markers of insulin resistance.
Author Summary
Serum adiponectin levels are highly heritable and are inversely correlated with the risk of type 2 diabetes (T2D), coronary artery disease, stroke, and several metabolic traits. To identify common genetic variants associated with adiponectin levels and risk of T2D and metabolic traits, we conducted a meta-analysis of genome-wide association studies of 45,891 multi-ethnic individuals. In addition to confirming that variants at the ADIPOQ and CDH13 loci influence adiponectin levels, our analyses revealed that 10 new loci also affecting circulating adiponectin levels. We demonstrated that expression levels of several genes in these candidate regions are associated with serum adiponectin levels. Using a powerful novel method to assess the contribution of the identified variants with other traits using summary-level results from large-scale GWAS consortia, we provide evidence that the risk alleles for adiponectin are associated with deleterious changes in T2D risk and metabolic syndrome traits (triglycerides, HDL, post-prandial glucose, insulin, and waist-to-hip ratio), demonstrating that the identified loci, taken together, impact upon metabolic disease.
doi:10.1371/journal.pgen.1002607
PMCID: PMC3315470  PMID: 22479202
13.  An 18-kDa Translocator Protein (TSPO) polymorphism explains differences in binding affinity of the PET radioligand PBR28 
[11C]PBR28 binds the 18-kDa Translocator Protein (TSPO) and is used in positron emission tomography (PET) to detect microglial activation. However, quantitative interpretations of signal are confounded by large interindividual variability in binding affinity, which displays a trimodal distribution compatible with a codominant genetic trait. Here, we tested directly for an underlying genetic mechanism to explain this. Binding affinity of PBR28 was measured in platelets isolated from 41 human subjects and tested for association with polymorphisms in TSPO and genes encoding other proteins in the TSPO complex. Complete agreement was observed between the TSPO Ala147Thr genotype and PBR28 binding affinity phenotype (P value=3.1 × 10−13). The TSPO Ala147Thr polymorphism predicts PBR28 binding affinity in human platelets. As all second-generation TSPO PET radioligands tested hitherto display a trimodal distribution in binding affinity analogous to PBR28, testing for this polymorphism may allow quantitative interpretation of TSPO PET studies with these radioligands.
doi:10.1038/jcbfm.2011.147
PMCID: PMC3323305  PMID: 22008728
Ala147Thr; PBR28; polymorphism; radioligand binding; TSPO
14.  FGF21 signalling pathway and metabolic traits – genetic association analysis 
European Journal of Human Genetics  2010;18(12):1344-1348.
Fibroblast growth factor 21 (FGF21) is a novel master regulator of metabolic profile. The biological actions of FGF21 are elicited upon its klotho beta (KLB)-facilitated binding to FGF receptor 1 (FGFR1), FGFR2 and FGFR3. We hypothesised that common polymorphisms in the FGF21 signalling pathway may be associated with metabolic risk. At the screening stage, we examined associations between 63 common single-nucleotide polymorphisms (SNPs) in five genes of this pathway (FGF21, KLB, FGFR1, FGFR2, FGFR3) and four metabolic phenotypes (LDL cholesterol – LDL-C, HDL-cholesterol – HDL-C, triglycerides and body mass index) in 629 individuals from Silesian Hypertension Study (SHS). Replication analyses were performed in 5478 unrelated individuals of the Swiss CoLaus cohort (imputed genotypes) and in 3030 directly genotyped individuals of the German Myocardial Infarction Family Study (GerMIFS). Of 54 SNPs that met quality control criteria after genotyping in SHS, 4 (rs4733946 and rs7012413 in FGFR1; rs2071616 in FGFR2 and rs7670903 in KLB) showed suggestive association with LDL-C (P=0.0006, P=0.0013, P=0.0055, P=0.011, respectively) and 1 (rs2608819 in KLB) was associated with body mass index (P=0.011); all with false discovery rate q<0.5. Of these, only one FGFR2 polymorphism (rs2071616) showed replicated association with LDL-C in both CoLaus (P=0.009) and men from GerMIFS (P=0.017). The direction of allelic effect of rs2071616 upon LDL-C was consistent in all examined populations. These data show that common genetic variations in FGFR2 may be associated with LDL-C in subjects of white European ancestry.
doi:10.1038/ejhg.2010.130
PMCID: PMC2988092  PMID: 20717167
fibroblast growth factor 21; fibroblast growth factor receptor 2; cholesterol; single-nucleotide polymorphism; genome-wide association studies
15.  GENETIC ARCHITECTURE OF AMBULATORY BLOOD PRESSURE IN THE GENERAL POPULATION – INSIGHTS FROM CARDIOVASCULAR GENE-CENTRIC ARRAY 
Hypertension  2010;56(6):1069-1076.
Genetic determinants of blood pressure are poorly defined. We undertook a large-scale gene-centric analysis to identify loci and pathways associated with ambulatory systolic and diastolic blood pressure.
We measured 24-hour ambulatory BP in 2020 individuals from 520 white European nuclear families (the GRAPHIC Study) and genotyped their DNA using the Illumina HumanCVD BeadChip array which contains approximately 50000 single nucleotide polymorphisms in >2000 cardiovascular candidate loci. We found a strong association between rs13306560 polymorphism in the promoter region of MTHFR and CLCN6 and mean 24-hour diastolic blood pressure - each minor allele copy of rs13306560 was associated with 2.6 mmHg lower mean 24-hour diastolic blood pressure (P=1.2×10−8). rs13306560 was also associated with clinic diastolic blood pressure in a combined analysis of 8129 subjects from the GRAPHIC Study, the CoLaus Study and the Silesian Cardiovascular Study (P=5.4×10−6). Additional analysis of associations between variants in Gene Ontology-defined pathways and mean 24-hour blood pressure in the GRAPHIC Study showed that cell survival control signalling cascades could play a role in blood pressure regulation. There was also a significant over-representation of rare variants (minor allele frequency <0.05) amongst polymorphisms showing at least nominal association with mean 24-hour blood pressure indicating that a considerable proportion of its heritability may be explained by uncommon alleles.
Through a large scale gene-centric analysis of ambulatory blood pressure, we identified an association of a novel variant at the MTHFR/CLNC6 locus with diastolic blood pressure and provided new insights into the genetic architecture of blood pressure.
doi:10.1161/HYPERTENSIONAHA.110.155721
PMCID: PMC3035934  PMID: 21060006
gene; genetics; blood pressure; single nucleotide polymorphism; association; heritability
16.  Association between Variants of the Leptin Receptor Gene (LEPR) and Overweight: A Systematic Review and an Analysis of the CoLaus Study 
PLoS ONE  2011;6(10):e26157.
Background
Three non-synonymous single nucleotide polymorphisms (Q223R, K109R and K656N) of the leptin receptor gene (LEPR) have been tested for association with obesity-related outcomes in multiple studies, showing inconclusive results. We performed a systematic review and meta-analysis on the association of the three LEPR variants with BMI. In addition, we analysed 15 SNPs within the LEPR gene in the CoLaus study, assessing the interaction of the variants with sex.
Methodology/Principal Findings
We searched electronic databases, including population-based studies that investigated the association between LEPR variants Q223R, K109R and K656N and obesity- related phenotypes in healthy, unrelated subjects. We furthermore performed meta-analyses of the genotype and allele frequencies in case-control studies. Results were stratified by SNP and by potential effect modifiers. CoLaus data were analysed by logistic and linear regressions and tested for interaction with sex. The meta-analysis of published data did not show an overall association between any of the tested LEPR variants and overweight. However, the choice of a BMI cut-off value to distinguish cases from controls was crucial to explain heterogeneity in Q223R. Differences in allele frequencies across ethnic groups are compatible with natural selection of derived alleles in Q223R and K109R and of the ancient allele in K656N in Asians. In CoLaus, the rs10128072, rs3790438 and rs3790437 variants showed interaction with sex for their association with overweight, waist circumference and fat mass in linear regressions.
Conclusions
Our systematic review and analysis of primary data from the CoLaus study did not show an overall association between LEPR SNPs and overweight. Most studies were underpowered to detect small effect sizes. A potential effect modification by sex, population stratification, as well as the role of natural selection should be addressed in future genetic association studies.
doi:10.1371/journal.pone.0026157
PMCID: PMC3196514  PMID: 22028824
17.  Hyperhomocysteinemia is independently associated with albuminuria in the population-based CoLaus study 
BMC Public Health  2011;11:733.
Background
Increased serum levels of homocysteine and uric acid have each been associated with cardiovascular risk. We analyzed whether homocysteine and uric acid were associated with glomerular filtration rate (GFR) and albuminuria independently of each other. We also investigated the association of MTHFR polymorphisms related to homocysteine with albuminuria to get further insight into causality.
Methods
This was a cross-sectional population-based study in Caucasians (n = 5913). Hyperhomocysteinemia was defined as total serum homocysteine ≥ 15 μmol/L. Albuminuria was defined as urinary albumin-to-creatinine ratio > 30 mg/g.
Results
Uric acid was associated positively with homocysteine (r = 0.246 in men and r = 0.287 in women, P < 0.001). The prevalence of albuminuria increased across increasing homocysteine categories (from 6.4% to 17.3% in subjects with normal GFR and from 3.5% to 14.5% in those with reduced GFR, P for trend < 0.005). Hyperhomocysteinemia (OR = 2.22, 95% confidence interval: 1.60-3.08, P < 0.001) and elevated serum uric acid (OR = 1.27, 1.08-1.50, per 100 μmol/L, P = 0.004) were significantly associated with albuminuria, independently of hypertension and type 2 diabetes. The 2-fold higher risk of albuminuria associated with hyperhomocysteinemia was similar to the risk associated with hypertension or diabetes. MTHFR alleles related to higher homocysteine were associated with increased risk of albuminuria.
Conclusions
In the general adult population, elevated serum homocysteine and uric acid were associated with albuminuria independently of each other and of renal function.
doi:10.1186/1471-2458-11-733
PMCID: PMC3188498  PMID: 21943240
18.  Performance of Genotype Imputation for Rare Variants Identified in Exons and Flanking Regions of Genes 
PLoS ONE  2011;6(9):e24945.
Genotype imputation has the potential to assess human genetic variation at a lower cost than assaying the variants using laboratory techniques. The performance of imputation for rare variants has not been comprehensively studied. We utilized 8865 human samples with high depth resequencing data for the exons and flanking regions of 202 genes and Genome-Wide Association Study (GWAS) data to characterize the performance of genotype imputation for rare variants. We evaluated reference sets ranging from 100 to 3713 subjects for imputing into samples typed for the Affymetrix (500K and 6.0) and Illumina 550K GWAS panels. The proportion of variants that could be well imputed (true r2>0.7) with a reference panel of 3713 individuals was: 31% (Illumina 550K) or 25% (Affymetrix 500K) with MAF (Minor Allele Frequency) less than or equal 0.001, 48% or 35% with 0.0010.05. The performance for common SNPs (MAF>0.05) within exons and flanking regions is comparable to imputation of more uniformly distributed SNPs. The performance for rare SNPs (0.01
doi:10.1371/journal.pone.0024945
PMCID: PMC3176314  PMID: 21949800
Although experimental studies have suggested that insulin-like growth factor I (IGF-I) and its binding protein IGFBP-3 might have a role in the aetiology of coronary artery disease (CAD), the relevance of circulating IGFs and their binding proteins in the development of CAD in human populations is unclear. We conducted a nested case-control study, with a mean follow-up of six years, within the EPIC-Norfolk cohort to assess the association between circulating levels of IGF-I and IGFBP-3 and risk of CAD in up to 1,013 cases and 2,055 controls matched for age, sex and study enrolment date. After adjustment for cardiovascular risk factors, we found no association between circulating levels of IGF-I or IGFBP-3 and risk of CAD (odds ratio: 0.98 (95% Cl 0.90-1.06) per 1 SD increase in circulating IGF-I; odds ratio: 1.02 (95% Cl 0.94-1.12) for IGFBP-3). We examined associations between tagging single nucleotide polymorphisms (tSNPs) at the IGF1 and IGFBP3 loci and circulating IGF-I and IGFBP-3 levels in up to 1,133 cases and 2,223 controls and identified three tSNPs (rs1520220, rs3730204, rs2132571) that showed independent association with either circulating IGF-I or IGFBP-3 levels. In an assessment of 31 SNPs spanning the IGF1 or IGFBP3 loci, none were associated with risk of CAD in a meta-analysis that included EPIC-Norfolk and eight additional studies comprising up to 9,319 cases and 19,964 controls. Our results indicate that IGF-I and IGFBP-3 are unlikely to be importantly involved in the aetiology of CAD in human populations.
PMCID: PMC3166154  PMID: 21915365
Epidemiology; Genetics of cardiovascular disease; Risk factors; IGF1; IGFBP3
Pathway-based association methods have been proposed to be an effective approach in identifying disease genes, when single-marker association tests do not have sufficient power. The analysis of quantitative traits may be benefited from these approaches, by sampling from two extreme tails of the distribution. Here we tested a pathway association approach on a small genome-wide association study (GWAS) on 653 subjects with extremely high high-density lipoprotein cholesterol (HDL-C) levels and 784 subjects with low HDL-C levels. We identified 102 genes in the sterol transport and metabolism pathways that collectively associate with HDL-C levels, and replicated these association signals in an independent GWAS. Interestingly, the pathways include 18 genes implicated in previous GWAS on lipid traits, suggesting that genuine HDL-C genes are highly enriched in these pathways. Additionally, multiple biologically relevant loci in the pathways were not detected by previous GWAS, including genes implicated in previous candidate gene association studies (such as LEPR, APOA2, HDLBP, SOAT2), genes that cause Mendelian forms of lipid disorders (such as DHCR24), and genes expressing dyslipidemia phenotypes in knockout mice (such as SOAT1, PON1). Our study suggests that sampling from two extreme tails of a quantitative trait and examining genetic pathways may yield biological insights from smaller samples than are generally required using single-marker analysis in large-scale GWAS. Our results also implicate that functionally related genes work together to regulate complex quantitative traits, and that future large-scale studies may benefit from pathway-association approaches to identify novel pathways regulating HDL-C levels.
doi:10.3389/fgene.2011.00041
PMCID: PMC3268595  PMID: 22303337
GWAS; lipid; HDL-C; pathway analysis; cholesterol; sterol transport; sterol metabolism; genetic association
Soranzo, Nicole | Spector, Tim D | Mangino, Massimo | Kühnel, Brigitte | Rendon, Augusto | Teumer, Alexander | Willenborg, Christina | Wright, Benjamin | Chen, Li | Li, Mingyao | Salo, Perttu | Voight, Benjamin F | Burns, Philippa | Laskowski, Roman A | Xue, Yali | Menzel, Stephan | Altshuler, David | Bradley, John R | Bumpstead, Suzannah | Burnett, Mary-Susan | Devaney, Joseph | Döring, Angela | Elosua, Roberto | Epstein, Stephen | Erber, Wendy | Falchi, Mario | Garner, Stephen F | Ghori, Mohammed J R | Goodall, Alison H | Gwilliam, Rhian | Hakonarson, Hakon H | Hall, Alistair S | Hammond, Naomi | Hengstenberg, Christian | Illig, Thomas | König, Inke R | Knouff, Christopher W | McPherson, Ruth | Melander, Olle | Mooser, Vincent | Nauck, Matthias | Nieminen, Markku S | O’Donnell, Christopher J | Peltonen, Leena | Potter, Simon C | Prokisch, Holger | Rader, Daniel J | Rice, Catherine M | Roberts, Robert | Salomaa, Veikko | Sambrook, Jennifer | Schreiber, Stefan | Schunkert, Heribert | Schwartz, Stephen M | Serbanovic-Canic, Jovana | Sinisalo, Juha | Siscovick, David S. | Stark, Klaus | Surakka, Ida | Stephens, Jonathan | Thompson, John R | Völker, Uwe | Völzke, Henry | Watkins, Nicholas A | Wells, George A | Wichmann, H-Erich | Van Heel, David A | Tyler-Smith, Chris | Thein, Swee Lay | Kathiresan, Sekar | Perola, Markus | Reilly, Muredach P | Stewart, Alexandre F R | Erdmann, Jeanette | Samani, Nilesh J | Meisinger, Christa | Greinacher, Andreas | Deloukas, Panos | Ouwehand, Willem H | Gieger, Christian
Nature genetics  2009;41(11):1182-1190.
The number and volume of cells in the blood affect a wide range of disorders including cancer and cardiovascular, metabolic, infectious and immune conditions. We consider here the genetic variation in eight clinically relevant hematological parameters, including hemoglobin levels, red and white blood cell counts and platelet counts and volume. We describe common variants within 22 genetic loci reproducibly associated with these hematological parameters in 13,943 samples from six European population-based studies, including 6 associated with red blood cell parameters, 15 associated with platelet parameters and 1 associated with total white blood cell count. We further identified a long-range haplotype at 12q24 associated with coronary artery disease in 9,479 cases and 10,527 controls. We show that this haplotype demonstrates extensive disease pleiotropy, as it contains known risk loci for type 1 diabetes, hypertension and celiac disease and has been spread by a selective sweep specific to European and geographically nearby populations.
doi:10.1038/ng.467
PMCID: PMC3108459  PMID: 19820697
Fibroblast growth factor 21 (FGF21) is a novel master regulator of metabolic profile. The biological actions of FGF21 are elicited upon its klotho beta (KLB)-facilitated binding to FGF receptor 1 (FGFR1), FGF receptor 2 (FGFR2) and FGF receptor 3 (FGFR3). We hypothesised that common polymorphisms in the FGF21 signalling pathway may be associated with metabolic risk. At the screening stage we examined associations between 63 common single nucleotide polymorphisms (SNPs) in 5 genes of this pathway (FGF21, KLB, FGFR1, FGFR2, FGFR3) and 4 metabolic phenotypes (LDL cholesterol - LDL-C, HDL-cholesterol, triglycerides and body mass index - BMI) in 629 individuals from Silesian Hypertension Study. Replication analyses were performed in 5,478 unrelated individuals of the Swiss CoLaus cohort (imputed genotypes) and in 3,030 directly genotyped individuals of the German Myocardial Infarction Family Study. Of 54 SNPs that met quality control criteria after genotyping in Silesian Hypertension Study, four (rs4733946 and rs7012413 in FGFR1; rs2071616 in FGFR2 and rs7670903 in KLB) showed suggestive association with LDL-C (p=0.0006, p=0.0013, p=0.0055, p=0.011, respectively) and one (rs2608819 in KLB) was associated with BMI (p=0.011); all with false discovery rate q<0.5. Of these, only one FGFR2 polymorphism (rs2071616) showed replicated association with LDL-C in both the CoLaus cohort (p=0.009) and men from the German Myocardial Infarction Family Study (p=0.017). The direction of allelic effect of rs2071616 upon LDL-C was consistent in all examined populations. These data show that common genetic variation in FGFR2 may be associated with LDL-C in subjects of white European ancestry.
doi:10.1038/ejhg.2010.130
PMCID: PMC2988092  PMID: 20717167
fibroblast growth factor 21; fibroblast growth factor receptor 2; cholesterol; single nucleotide polymorphism; genome-wide association studies
Background Cigarette smoking is associated with lower body mass index (BMI), and a commonly cited reason for unwillingness to quit smoking is a concern about weight gain. Common variation in the CHRNA5-CHRNA3-CHRNB4 gene region (chromosome 15q25) is robustly associated with smoking quantity in smokers, but its association with BMI is unknown. We hypothesized that genotype would accurately reflect smoking exposure and that, if smoking were causally related to weight, it would be associated with BMI in smokers, but not in never smokers.
Methods We stratified nine European study samples by smoking status and, in each stratum, analysed the association between genotype of the 15q25 SNP, rs1051730, and BMI. We meta-analysed the results (n = 24 198) and then tested for a genotype × smoking status interaction.
Results There was no evidence of association between BMI and genotype in the never smokers {difference per T-allele: 0.05 kg/m2 [95% confidence interval (95% CI): −0.05 to 0.18]; P = 0.25}. However, in ever smokers, each additional smoking-related T-allele was associated with a 0.23 kg/m2 (95% CI: 0.13–0.31) lower BMI (P = 8 × 10−6). The effect size was larger in current [0.33 kg/m2 lower BMI per T-allele (95% CI: 0.18–0.48); P = 6 × 10−5], than in former smokers [0.16 kg/m2 (95% CI: 0.03–0.29); P = 0.01]. There was strong evidence of genotype × smoking interaction (P = 0.0001).
Conclusions Smoking status modifies the association between the 15q25 variant and BMI, which strengthens evidence that smoking exposure is causally associated with reduced BMI. Smoking cessation initiatives might be more successful if they include support to maintain a healthy BMI.
doi:10.1093/ije/dyr077
PMCID: PMC3235017  PMID: 21593077
Smoking; BMI; SNP; genetic association; interaction
PLoS ONE  2011;6(4):e18865.
Background
Associations of serum calcium levels with the metabolic syndrome and other novel cardio-metabolic risk factors not classically included in the metabolic syndrome, such as those involved in oxidative stress, are largely unexplored. We analyzed the association of albumin-corrected serum calcium levels with conventional and non-conventional cardio-metabolic risk factors in a general adult population.
Methodology/Principal Findings
The CoLaus study is a population-based study including Caucasians from Lausanne, Switzerland. The metabolic syndrome was defined using the Adult Treatment Panel III criteria. Non-conventional cardio-metabolic risk factors considered included: fat mass, leptin, LDL particle size, apolipoprotein B, fasting insulin, adiponectin, ultrasensitive CRP, serum uric acid, homocysteine, and gamma-glutamyltransferase. We used adjusted standardized multivariable regression to compare the association of each cardio-metabolic risk factor with albumin-corrected serum calcium. We assessed associations of albumin-corrected serum calcium with the cumulative number of non-conventional cardio-metabolic risk factors.
We analyzed 4,231 subjects aged 35 to 75 years. Corrected serum calcium increased with both the number of the metabolic syndrome components and the number of non-conventional cardio-metabolic risk factors, independently of the metabolic syndrome and BMI. Among conventional and non-conventional cardio-metabolic risk factors, the strongest positive associations were found for factors related to oxidative stress (uric acid, homocysteine and gamma-glutamyltransferase). Adiponectin had the strongest negative association with corrected serum calcium.
Conclusions/Significance
Serum calcium was associated with the metabolic syndrome and with non-conventional cardio-metabolic risk factors independently of the metabolic syndrome. Associations with uric acid, homocysteine and gamma-glutamyltransferase were the strongest. These novel findings suggest that serum calcium levels may be associated with cardiovascular risk via oxidative stress.
doi:10.1371/journal.pone.0018865
PMCID: PMC3080882  PMID: 21533040
PLoS ONE  2011;6(4):e18208.
Background
The Asia-specific PLA2G7 994G-T transversion leads to V279F substitution within the lipoprotein-associated phospholipase-A2 (Lp-PLA2) and to absence of enzyme activity in plasma. This variant offers a unique natural experiment to assess the role of Lp-PLA2 in the pathogenesis of coronary artery disease (CAD) in humans. Given conflicting results from mostly small studies, a large two-stage case-control study was warranted.
Methodology/Principal Findings
PLA2G7 V279F genotypes were initially compared in 2890 male cases diagnosed with CAD before age 60 with 3128 male controls without CAD at age 50 and above and subsequently in a second independent male dataset of 877 CAD cases and 1230 controls. In the first dataset, the prevalence of the 279F null allele was 11.5% in cases and 12.8% in controls. After adjustment for age, body mass index, diabetes, smoking, glucose and lipid levels, the OR (95% CI) for CAD for this allele was 0.80 (0.66–0.97, p = 0.02). The results were very similar in the second dataset, despite lower power, with an allele frequency of 11.2% in cases and 12.5% in controls, leading to a combined OR of 0.80 (0.69–0.92), p = 0.002. The magnitude and direction of this genetic effect were fully consistent with large epidemiological studies on plasma Lp-PLA2 activity and CAD risk.
Conclusions
Natural deficiency in Lp-PLA2 activity due to carriage of PLA2G7 279F allele protects from CAD in Korean men. These results provide evidence for a causal relationship between Lp-PLA2 and CAD, and support pharmacological inhibition of this enzyme as an innovative way to prevent CAD.
doi:10.1371/journal.pone.0018208
PMCID: PMC3071750  PMID: 21490708

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