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van der Valk RJ, Duijts L, Timpson NJ, Salam MT, Standl M, Curtin JA, Genuneit J, Kerhof M, Kreiner-Møller E, Cáceres A, Gref A, Liang LL, Taal HR, Bouzigon E, Demenais F, Nadif R, Ober C, Thompson EE, Estrada K, Hofman A, Uitterlinden AG, van Duijn C, Rivadeneira F, Li X, Eckel SP, Berhane K, Gauderman WJ, Granell R, Evans DM, St Pourcain B, McArdle W, Kemp JP, Smith GD, Tiesler CM, Flexeder C, Simpson A, Murray CS, Fuchs O, Postma DS, Bønnelykke K, Torrent M, Andersson M, Sleiman P, Hakonarson H, Cookson WO, Moffatt MF, Paternoster L, Melén E, Sunyer J, Bisgaard H, Koppelman GH, Ege M, Custovic A, Heinrich J, Gilliland FD, Henderson AJ, Jaddoe VW, de Jongste JC. Fraction of exhaled nitric oxide values in childhood are associated with 17q11.2-q12 and 17q12-q21 variants. J Allergy Clin Immunol 2014; 134:46-55. [PMID: 24315451 PMCID: PMC4334587 DOI: 10.1016/j.jaci.2013.08.053] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 06/21/2013] [Accepted: 08/28/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND The fraction of exhaled nitric oxide (Feno) value is a biomarker of eosinophilic airway inflammation and is associated with childhood asthma. Identification of common genetic variants associated with childhood Feno values might help to define biological mechanisms related to specific asthma phenotypes. OBJECTIVE We sought to identify the genetic variants associated with childhood Feno values and their relation with asthma. METHODS Feno values were measured in children age 5 to 15 years. In 14 genome-wide association studies (N = 8,858), we examined the associations of approximately 2.5 million single nucleotide polymorphisms (SNPs) with Feno values. Subsequently, we assessed whether significant SNPs were expression quantitative trait loci in genome-wide expression data sets of lymphoblastoid cell lines (n = 1,830) and were related to asthma in a previously published genome-wide association data set (cases, n = 10,365; control subjects: n = 16,110). RESULTS We identified 3 SNPs associated with Feno values: rs3751972 in LYR motif containing 9 (LYRM9; P = 1.97 × 10(-10)) and rs944722 in inducible nitric oxide synthase 2 (NOS2; P = 1.28 × 10(-9)), both of which are located at 17q11.2-q12, and rs8069176 near gasdermin B (GSDMB; P = 1.88 × 10(-8)) at 17q12-q21. We found a cis expression quantitative trait locus for the transcript soluble galactoside-binding lectin 9 (LGALS9) that is in linkage disequilibrium with rs944722. rs8069176 was associated with GSDMB and ORM1-like 3 (ORMDL3) expression. rs8069176 at 17q12-q21, but not rs3751972 and rs944722 at 17q11.2-q12, were associated with physician-diagnosed asthma. CONCLUSION This study identified 3 variants associated with Feno values, explaining 0.95% of the variance. Identification of functional SNPs and haplotypes in these regions might provide novel insight into the regulation of Feno values. This study highlights that both shared and distinct genetic factors affect Feno values and childhood asthma.
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Berhane K, Zhang Y, Salam MT, Eckel SP, Linn WS, Rappaport EB, Bastain TM, Lurmann F, Gilliland FD. Longitudinal effects of air pollution on exhaled nitric oxide: the Children's Health Study. Occup Environ Med 2014; 71:507-13. [PMID: 24696513 DOI: 10.1136/oemed-2013-101874] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVES To assess the effects of long-term variations in ambient air pollutants on longitudinal changes in exhaled nitric oxide (FeNO), a potentially useful biomarker of eosinophilic airway inflammation, based on data from the southern California Children's Health Study. METHODS Based on a cohort of 1211 schoolchildren from eight Southern California communities with FeNO measurements in 2006-2007 and 2007-2008, regression models adjusted for short-term effects of air pollution were fitted to assess the association between changes in annual long-term exposures and changes in FeNO. RESULTS Increases in annual average concentrations of 24-h average NO2 and PM2.5 (scaled to the IQR of 1.8 ppb and 2.4 μg/m(3), respectively) were associated with a 2.29 ppb (CI 0.36 to 4.21; p=0.02) and a 4.94 ppb (CI 1.44 to 8.47; p=0.005) increase in FeNO, respectively, after adjustments for short-term effects of the respective pollutants. In contrast, changes in annual averages of PM10 and O3 were not significantly associated with changes in FeNO. These findings did not differ significantly by asthma status. CONCLUSIONS Changes in annual average exposure to current levels of ambient air pollutants are significantly associated with changes in FeNO levels in children, independent of short-term exposures and asthma status. Use of this biomarker in population-based epidemiological research has great potential for assessing the impact of changing real world mixtures of ambient air pollutants on children's respiratory health.
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Breton CV, Park C, Siegmund K, Gauderman WJ, Whitfield-Maxwell L, Hodis HN, Avol E, Gilliland FD. NOS1 methylation and carotid artery intima-media thickness in children. ACTA ACUST UNITED AC 2014; 7:116-22. [PMID: 24622112 DOI: 10.1161/circgenetics.113.000320] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Nitric oxide (NO) plays an important role in cardiovascular health by maintaining and regulating vascular tone and blood flow. Epigenetic regulation of NO synthase (NOS), the genes responsible for NO production, may affect cardiovascular disease, including the development of atherosclerosis in children. METHODS AND RESULTS We measured percentage DNA methylation using bisulfite conversion and pyrosequencing assays on DNA from buccal cells provided by 377 participants of the Children's Health Study on whom carotid artery intima-media thickness (CIMT) measurements were also collected. We examined a total of 16 CpG loci located within NOS1, NOS2A, NOS3, ARG1, and ARG2 genes responsible for NO production. CIMT was measured using high-resolution B-mode carotid ultrasound. The association between percentage DNA methylation in ARG and NOS genes with CIMT was evaluated using linear regression adjusted for sex, ethnicity, body mass index, age at CIMT, town of residence, and experimental plate for pyrosequencing reactions. Differences in the association by ethnicity and ancestral group were also evaluated. For a 1% increase in average DNA methylation of NOS1, CIMT increased by 1.2 μm (P=0.02). This association was greater in Hispanic children of Native American descent (β=2.3; P=0.004) than in non-Hispanic whites (β=0.3; P=0.71) or Hispanic whites (β=1.0; P=0.35). CONCLUSIONS DNA methylation of NOS1 has a plausible role in atherogenesis through regulation of NO production, although ancestry may alter the magnitude of this association.
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Fruin S, Urman R, Lurmann F, McConnell R, Gauderman J, Rappaport E, Franklin M, Gilliland FD, Shafer M, Gorski P, Avol E. Spatial Variation in Particulate Matter Components over a Large Urban Area. ATMOSPHERIC ENVIRONMENT (OXFORD, ENGLAND : 1994) 2014; 83:211-219. [PMID: 24578605 PMCID: PMC3932493 DOI: 10.1016/j.atmosenv.2013.10.063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
To characterize exposures to particulate matter (PM) and its components, we performed a large sampling study of small-scale spatial variation in size-resolved particle mass and composition. PM was collected in size ranges of < 0.2, 0.2-to-2.5, and 2.5-to-10 μm on a scale of 100s to 1000s of meters to capture local sources. Within each of eight Southern California communities, up to 29 locations were sampled for rotating, month-long integrated periods at two different times of the year, six months apart, from Nov 2008 through Dec 2009. Additional sampling was conducted at each community's regional monitoring station to provide temporal coverage over the sampling campaign duration. Residential sampling locations were selected based on a novel design stratified by high- and low-predicted traffic emissions and locations over- and under-predicted from previous dispersion model and sampling comparisons. Primary vehicle emissions constituents, such as elemental carbon (EC), showed much stronger patterns of association with traffic than pollutants with significant secondary formation, such as PM2.5 or water soluble organic carbon. Associations were also stronger during cooler times of the year (Oct through Mar). Primary pollutants also showed greater within-community spatial variation compared to pollutants with secondary formation contributions. For example, the average cool-season community mean and standard deviation (SD) for EC were 1.1 and 0.17 μg/m3, respectively, giving a coefficient of variation (CV) of 18%. For PM2.5, average mean and SD were 14 and 1.3 μg/m3, respectively, with a CV of 9%. We conclude that within-community spatial differences are important for accurate exposure assessment of traffic-related pollutants.
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Eckel SP, Linn WS, Berhane K, Rappaport EB, Salam MT, Zhang Y, Gilliland FD. Estimation of parameters in the two-compartment model for exhaled nitric oxide. PLoS One 2014; 9:e85471. [PMID: 24465571 PMCID: PMC3894971 DOI: 10.1371/journal.pone.0085471] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 11/27/2013] [Indexed: 01/13/2023] Open
Abstract
The fractional concentration of exhaled nitric oxide (FeNO) is a biomarker of airway inflammation that is being increasingly considered in clinical, occupational, and epidemiological applications ranging from asthma management to the detection of air pollution health effects. FeNO depends strongly on exhalation flow rate. This dependency has allowed for the development of mathematical models whose parameters quantify airway and alveolar compartment contributions to FeNO. Numerous methods have been proposed to estimate these parameters using FeNO measured at multiple flow rates. These methods—which allow for non-invasive assessment of localized airway inflammation—have the potential to provide important insights on inflammatory mechanisms. However, different estimation methods produce different results and a serious barrier to progress in this field is the lack of a single recommended method. With the goal of resolving this methodological problem, we have developed a unifying framework in which to present a comprehensive set of existing and novel statistical methods for estimating parameters in the simple two-compartment model. We compared statistical properties of the estimators in simulation studies and investigated model fit and parameter estimate sensitivity across methods using data from 1507 schoolchildren from the Southern California Children's Health Study, one of the largest multiple flow FeNO studies to date. We recommend a novel nonlinear least squares model with natural log transformation on both sides that produced estimators with good properties, satisfied model assumptions, and fit the Children's Health Study data well.
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Breton CV, Yin F, Wang X, Avol E, Gilliland FD, Araujo JA. HDL anti-oxidant function associates with LDL level in young adults. Atherosclerosis 2014; 232:165-70. [PMID: 24401232 PMCID: PMC4039385 DOI: 10.1016/j.atherosclerosis.2013.10.034] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 10/23/2013] [Accepted: 10/31/2013] [Indexed: 12/19/2022]
Abstract
OBJECTIVES The primary objective was to evaluate predictors of HDL anti-oxidant function in young adults. BACKGROUND High-density lipoprotein (HDL) cholesterol is considered a protective factor for cardiovascular disease (CVD). However, increased levels are not always associated with decreased cardiovascular risk. A better understanding of the importance of HDL functionality and how it affects CVD risk is needed. METHODS Fifty non-Hispanic white subjects from the Testing Responses on Youth (TROY) study were randomly selected to investigate whether differences in HDL anti-oxidant function are associated with traditional cardiovascular risk factors, including carotid intima media thickness (CIMT), arterial stiffness and other inflammatory/metabolic parameters. HDL anti-oxidant capacity was evaluated by assessing its ability to inhibit low-density lipoprotein (LDL) cholesterol oxidation by air using a DCF-based fluorescent assay and expressed as a HDL oxidant index (HOI). The associations between HOI and other variables were assessed using both linear and logistic regression. RESULTS Eleven subjects (25%) had an HOI ≥ 1, indicating a pro-oxidant HDL. Age, LDL, high sensitivity C-reactive protein (hsCRP), and paraoxonase activity (PON1), but not HDL, were all associated with HOI level in univariate linear regression models. In multivariate models that mutually adjusted for these variables, LDL remained the strongest predictor of HOI (0.13 increase in HOI per 1 SD increase in LDL, 95% CI 0.04, 0.22). Atherogenic index of plasma, pulse pressure, homocysteine, glucose, insulin, CIMT and measurements of arterial stiffness were not associated with HOI in this population. CONCLUSIONS These results suggest LDL, hsCRP and DBP might predict HDL anti-oxidant function at an early age.
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Leng S, Liu Y, Thomas CL, Gauderman WJ, Picchi MA, Bruse SE, Zhang X, Flores KG, Van Den Berg D, Stidley CA, Gilliland FD, Belinsky SA. Native American ancestry affects the risk for gene methylation in the lungs of Hispanic smokers from New Mexico. Am J Respir Crit Care Med 2013; 188:1110-6. [PMID: 24032348 DOI: 10.1164/rccm.201305-0925oc] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
RATIONALE Gene promoter methylation detected in sputum predicts lung cancer risk in smokers. Compared with non-Hispanic whites (NHW), Hispanics have a lower age-standardized incidence for lung cancer. OBJECTIVES This study compared the methylation prevalence in sputum of NHWs with Hispanics using the Lovelace Smokers cohort (n = 1998) and evaluated the effect of Native American ancestry (NAA) and diet on biomarkers for lung cancer risk. METHODS Genetic ancestry was estimated using 48 ancestry markers. Diet was assessed by the Harvard University Dietary Assessment questionnaire. Methylation of 12 genes was measured in sputum using methylation-specific polymerase chain reaction. The association between NAA and risk for methylation was assessed using generalized estimating equations. The ethnic difference in the association between pack-years and risk for lung cancer was assessed in the New Mexico lung cancer study. MEASUREMENTS AND MAIN RESULTS Overall Hispanics had a significantly increased risk for methylation across the 12 genes analyzed (odds ratio, 1.18; P = 0.007). However, the risk was reduced by 32% (P = 0.032) in Hispanics with high versus low NAA. In the New Mexico lung cancer study, Hispanic non-small cell lung cancer cases have significantly lower pack-years than NHW counterparts (P = 0.007). Furthermore, compared with NHW smokers, Hispanic smokers had a more rapidly increasing risk for lung cancer as a function of pack-years (P = 0.058). CONCLUSIONS NAA may be an important risk modifier for methylation in Hispanic smokers. Smoking intensity may have a greater impact on risk for lung cancer in Hispanics compared with NHWs.
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Urman R, McConnell R, Islam T, Avol EL, Lurmann FW, Vora H, Linn WS, Rappaport EB, Gilliland FD, Gauderman WJ. Associations of children's lung function with ambient air pollution: joint effects of regional and near-roadway pollutants. Thorax 2013; 69:540-7. [PMID: 24253832 DOI: 10.1136/thoraxjnl-2012-203159] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Previous studies have reported adverse effects of either regional or near-roadway air pollution (NRAP) on lung function. However, there has been little study of the joint effects of these exposures. OBJECTIVES To assess the joint effects of NRAP and regional pollutants on childhood lung function in the Children's Health Study. METHODS Lung function was measured on 1811 children from eight Southern Californian communities. NRAP exposure was assessed based on (1) residential distance to the nearest freeway or major road and (2) estimated near-roadway contributions to residential nitrogen dioxide (NO2), nitric oxide (NO) and total nitrogen oxides (NOx). Exposure to regional ozone (O3), NO2, particulate matter with aerodynamic diameter <10 µm (PM10) and 2.5 µm (PM2.5) was measured continuously at community monitors. RESULTS An increase in near-roadway NOx of 17.9 ppb (2 SD) was associated with deficits of 1.6% in forced vital capacity (FVC) (p=0.005) and 1.1% in forced expiratory volume in 1 s (FEV1) (p=0.048). Effects were observed in all communities and were similar for NO2 and NO. Residential proximity to a freeway was associated with a reduction in FVC. Lung function deficits of 2-3% were associated with regional PM10 and PM2.5 (FVC and FEV1) and with O3 (FEV1), but not NO2 across the range of exposure between communities. Associations with regional pollution and NRAP were independent in models adjusted for each. The effects of NRAP were not modified by regional pollutant concentrations. CONCLUSIONS The results indicate that NRAP and regional air pollution have independent adverse effects on childhood lung function.
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Linn WS, Rappaport EB, Eckel SP, Berhane KT, Zhang Y, Salam MT, Bastain TM, Gilliland FD. Multiple-flow exhaled nitric oxide, allergy, and asthma in a population of older children. Pediatr Pulmonol 2013; 48:885-96. [PMID: 23687084 PMCID: PMC3748140 DOI: 10.1002/ppul.22708] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 09/24/2012] [Indexed: 11/12/2022]
Abstract
UNLABELLED "Extended" (multiple-flow) measurements of exhaled nitric oxide (FeNO) potentially can distinguish proximal and distal airway inflammation, but have not been evaluated previously in large populations. We performed extended NO testing within a longitudinal study of a school-based population, to relate bronchial flux (J'awNO) and peripheral NO concentration (CalvNO) estimates with respiratory health status determined from questionnaires. We measured FeNO at 30, 50, 100, and 300 ml/sec in 1,640 subjects aged 12-15 from eight communities, then estimated J'awNO and CalvNO from linear and nonlinear regressions of NO output versus flow. J'awNO, as well as FeNO at all flows, showed influences of asthma, allergy, Asian or African ancestry, age, and height (positive), and of weight (negative), generally corroborating past findings. By contrast, CalvNO results were inconsistent across different extended NO regression models, and appeared more sensitive to small measurement artifacts. CONCLUSIONS Extended NO testing is feasible in field surveys of young populations. In interpreting results, size, age, and ethnicity require attention, as well as instrumental and environmental artifacts. J'awNO and conventional FeNO provide similar information, probably reflecting proximal airway inflammation. CalvNO may give additional information relevant to peripheral airway, alveolar, or systemic pathology. However, it needs additional research, including testing of populations with independently verifiable peripheral or systemic pathology, to optimize measurement technique and interpretation.
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Tierney LA, Neft RE, Belinsky SA, Lauer FT, Gilliland FD, Crowell RE, Lechner JF. Double-label Suspension Immunohistochemistry for the Detection of Gene Dysfunction in Sputum. J Histotechnol 2013. [DOI: 10.1179/his.1997.20.1.13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Leng S, Picchi MA, Liu Y, Lin Y, Stidley CA, Gilliland FD, Jacobson MR, Belinsky SA. Abstract 3624: Genetic variation in SIRT1 affects susceptibility of lung squamous cell carcinomas in former uranium miners from the Colorado plateau. Cancer Res 2013. [DOI: 10.1158/1538-7445.am2013-3624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Epidemiological studies of underground miners suggest that occupational exposure to radon causes lung cancer with squamous cell carcinoma (SCC) as the predominant histological type. However, the genetic determinants for susceptibility of radon-induced SCC in miners are unclear. Double-strand breaks (DSBs) induced by radioactive radon daughters are repaired primarily by non-homologous end joining (NHEJ) that is accompanied by the dynamic changes in surrounding chromatin, including nucleosome repositioning and histone modifications. Thus, a molecular epidemiological study was conducted to assess whether genetic variation in 16 genes involved in NHEJ and related histone modification affected susceptibility for SCC in radon-exposed former miners (267 SCC cases and 383 controls) from the Colorado plateau. A global association between genetic variation in the haplotype block where SIRT1 resides and the risk for SCC in miners (P=0.003) was identified. Haplotype alleles tagged by the A allele of SIRT1 rs7097008 were associated with increased risk for SCC (Odds Ratio = 1.69, P = 8.2×10−5) and greater survival in SCC cases (Hazard Ratio = 0.79, P = 0.03) in miners. Functional validation of rs7097008 demonstrated that the A allele was associated with reduced gene expression in bronchial epithelial cells and compromised DNA repair capacity in peripheral lymphocytes. Together, these findings substantiate genetic variation in SIRT1 as a risk modifier for developing SCC in miners and suggested that SIRT1 may also play a tumor suppressor role in radon-induced cancer in miners.
Citation Format: Shuguang Leng, Maria A. Picchi, Yushi Liu, Yong Lin, Christine A. Stidley, Frank D. Gilliland, Marty R. Jacobson, Steven A. Belinsky. Genetic variation in SIRT1 affects susceptibility of lung squamous cell carcinomas in former uranium miners from the Colorado plateau. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3624. doi:10.1158/1538-7445.AM2013-3624
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Zhang R, Duhl T, Salam MT, House JM, Flagan RC, Avol EL, Gilliland FD, Guenther A, Chung SH, Lamb BK, VanReken TM. Development of a regional-scale pollen emission and transport modeling framework for investigating the impact of climate change on allergic airway disease. BIOGEOSCIENCES (ONLINE) 2013; 10:3977-4023. [PMID: 24839448 DOI: 10.5194/bg-11-1461-2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Exposure to bioaerosol allergens such as pollen can cause exacerbations of allergenic airway disease (AAD) in sensitive populations, and thus cause serious public health problems. Assessing these health impacts by linking the airborne pollen levels, concentrations of respirable allergenic material, and human allergenic response under current and future climate conditions is a key step toward developing preventive and adaptive actions. To that end, a regional-scale pollen emission and transport modeling framework was developed that treats allergenic pollens as non-reactive tracers within the WRF/CMAQ air-quality modeling system. The Simulator of the Timing and Magnitude of Pollen Season (STaMPS) model was used to generate a daily pollen pool that can then be emitted into the atmosphere by wind. The STaMPS is driven by species-specific meteorological (temperature and/or precipitation) threshold conditions and is designed to be flexible with respect to its representation of vegetation species and plant functional types (PFTs). The hourly pollen emission flux was parameterized by considering the pollen pool, friction velocity, and wind threshold values. The dry deposition velocity of each species of pollen was estimated based on pollen grain size and density. An evaluation of the pollen modeling framework was conducted for southern California for the period from March to June 2010. This period coincided with observations by the University of Southern California's Children's Health Study (CHS), which included O3, PM2.5, and pollen count, as well as measurements of exhaled nitric oxide in study participants. Two nesting domains with horizontal resolutions of 12 km and 4 km were constructed, and six representative allergenic pollen genera were included: birch tree, walnut tree, mulberry tree, olive tree, oak tree, and brome grasses. Under the current parameterization scheme, the modeling framework tends to underestimate walnut and peak oak pollen concentrations, and tends to overestimate grass pollen concentrations. The model shows reasonable agreement with observed birch, olive, and mulberry tree pollen concentrations. Sensitivity studies suggest that the estimation of the pollen pool is a major source of uncertainty for simulated pollen concentrations. Achieving agreement between emission modeling and observed pattern of pollen releases is the key for successful pollen concentration simulations.
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Liu J, Lewinger JP, Gilliland FD, Gauderman WJ, Conti DV. Confounding and heterogeneity in genetic association studies with admixed populations. Am J Epidemiol 2013; 177:351-60. [PMID: 23334005 DOI: 10.1093/aje/kws234] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Association studies among admixed populations pose many challenges including confounding of genetic effects due to population substructure and heterogeneity due to different patterns of linkage disequilibrium (LD). We use simulations to investigate controlling for confounding by indicators of global ancestry and the impact of including a covariate for local ancestry. In addition, we investigate the use of an interaction term between a single-nucleotide polymorphism (SNP) and local ancestry to capture heterogeneity in SNP effects. Although adjustment for global ancestry can control for confounding, additional adjustment for local ancestry may increase power when the induced admixture LD is in the opposite direction as the LD in the ancestral population. However, if the induced LD is in the same direction, there is the potential for reduced power because of overadjustment. Furthermore, the inclusion of a SNP by local ancestry interaction term can increase power when there is substantial differential LD between ancestry populations. We examine these approaches in genome-wide data using the University of Southern California's Children's Health Study investigating asthma risk. The analysis highlights rs10519951 (P = 8.5 × 10(-7)), a SNP lacking any evidence of association from a conventional analysis (P = 0.5).
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Himes BE, Sheppard K, Berndt A, Leme AS, Myers RA, Gignoux CR, Levin AM, Gauderman WJ, Yang JJ, Mathias RA, Romieu I, Torgerson DG, Roth LA, Huntsman S, Eng C, Klanderman B, Ziniti J, Senter-Sylvia J, Szefler SJ, Lemanske RF, Zeiger RS, Strunk RC, Martinez FD, Boushey H, Chinchilli VM, Israel E, Mauger D, Koppelman GH, Postma DS, Nieuwenhuis MAE, Vonk JM, Lima JJ, Irvin CG, Peters SP, Kubo M, Tamari M, Nakamura Y, Litonjua AA, Tantisira KG, Raby BA, Bleecker ER, Meyers DA, London SJ, Barnes KC, Gilliland FD, Williams LK, Burchard EG, Nicolae DL, Ober C, DeMeo DL, Silverman EK, Paigen B, Churchill G, Shapiro SD, Weiss ST. Integration of mouse and human genome-wide association data identifies KCNIP4 as an asthma gene. PLoS One 2013; 8:e56179. [PMID: 23457522 PMCID: PMC3572953 DOI: 10.1371/journal.pone.0056179] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 01/07/2013] [Indexed: 12/29/2022] Open
Abstract
Asthma is a common chronic respiratory disease characterized by airway hyperresponsiveness (AHR). The genetics of asthma have been widely studied in mouse and human, and homologous genomic regions have been associated with mouse AHR and human asthma-related phenotypes. Our goal was to identify asthma-related genes by integrating AHR associations in mouse with human genome-wide association study (GWAS) data. We used Efficient Mixed Model Association (EMMA) analysis to conduct a GWAS of baseline AHR measures from males and females of 31 mouse strains. Genes near or containing SNPs with EMMA p-values <0.001 were selected for further study in human GWAS. The results of the previously reported EVE consortium asthma GWAS meta-analysis consisting of 12,958 diverse North American subjects from 9 study centers were used to select a subset of homologous genes with evidence of association with asthma in humans. Following validation attempts in three human asthma GWAS (i.e., Sepracor/LOCCS/LODO/Illumina, GABRIEL, DAG) and two human AHR GWAS (i.e., SHARP, DAG), the Kv channel interacting protein 4 (KCNIP4) gene was identified as nominally associated with both asthma and AHR at a gene- and SNP-level. In EVE, the smallest KCNIP4 association was at rs6833065 (P-value 2.9e-04), while the strongest associations for Sepracor/LOCCS/LODO/Illumina, GABRIEL, DAG were 1.5e-03, 1.0e-03, 3.1e-03 at rs7664617, rs4697177, rs4696975, respectively. At a SNP level, the strongest association across all asthma GWAS was at rs4697177 (P-value 1.1e-04). The smallest P-values for association with AHR were 2.3e-03 at rs11947661 in SHARP and 2.1e-03 at rs402802 in DAG. Functional studies are required to validate the potential involvement of KCNIP4 in modulating asthma susceptibility and/or AHR. Our results suggest that a useful approach to identify genes associated with human asthma is to leverage mouse AHR association data.
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Leng S, Picchi MA, Liu Y, Thomas CL, Willis DG, Bernauer AM, Carr TG, Mabel PT, Han Y, Amos CI, Lin Y, Stidley CA, Gilliland FD, Jacobson MR, Belinsky SA. Genetic variation in SIRT1 affects susceptibility of lung squamous cell carcinomas in former uranium miners from the Colorado plateau. Carcinogenesis 2013; 34:1044-50. [PMID: 23354305 DOI: 10.1093/carcin/bgt024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Epidemiological studies of underground miners suggested that occupational exposure to radon causes lung cancer with squamous cell carcinoma (SCC) as the predominant histological type. However, the genetic determinants for susceptibility of radon-induced SCC in miners are unclear. Double-strand breaks induced by radioactive radon daughters are repaired primarily by non-homologous end joining (NHEJ) that is accompanied by the dynamic changes in surrounding chromatin, including nucleosome repositioning and histone modifications. Thus, a molecular epidemiological study was conducted to assess whether genetic variation in 16 genes involved in NHEJ and related histone modification affected susceptibility for SCC in radon-exposed former miners (267 SCC cases and 383 controls) from the Colorado plateau. A global association between genetic variation in the haplotype block where SIRT1 resides and the risk for SCC in miners (P = 0.003) was identified. Haplotype alleles tagged by the A allele of SIRT1 rs7097008 were associated with increased risk for SCC (odds ratio = 1.69, P = 8.2 × 10(-5)) and greater survival in SCC cases (hazard ratio = 0.79, P = 0.03) in miners. Functional validation of rs7097008 demonstrated that the A allele was associated with reduced gene expression in bronchial epithelial cells and compromised DNA repair capacity in peripheral lymphocytes. Together, these findings substantiate genetic variation in SIRT1 as a risk modifier for developing SCC in miners and suggest that SIRT1 may also play a tumor suppressor role in radon-induced cancer in miners.
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Levin AM, Mathias RA, Huang L, Roth LA, Daley D, Myers RA, Himes BE, Romieu I, Yang M, Eng C, Park JE, Zoratti K, Gignoux CR, Torgerson DG, Galanter JM, Huntsman S, Nguyen EA, Becker AB, Chan-Yeung M, Kozyrskyj AL, Kwok PY, Gilliland FD, Gauderman WJ, Bleecker ER, Raby BA, Meyers DA, London SJ, Martinez FD, Weiss ST, Burchard EG, Nicolae DL, Ober C, Barnes KC, Williams LK. A meta-analysis of genome-wide association studies for serum total IgE in diverse study populations. J Allergy Clin Immunol 2012; 131:1176-84. [PMID: 23146381 DOI: 10.1016/j.jaci.2012.10.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/28/2012] [Accepted: 10/02/2012] [Indexed: 01/27/2023]
Abstract
BACKGROUND IgE is both a marker and mediator of allergic inflammation. Despite reported differences in serum total IgE levels by race-ethnicity, African American and Latino subjects have not been well represented in genetic studies of total IgE. OBJECTIVE We sought to identify the genetic predictors of serum total IgE levels. METHODS We used genome-wide association data from 4292 subjects (2469 African Americans, 1564 European Americans, and 259 Latinos) in the EVE Asthma Genetics Consortium. Tests for association were performed within each cohort by race-ethnic group (ie, African American, Latino, and European American) and asthma status. The resulting P values were meta-analyzed, accounting for sample size and direction of effect. Top single nucleotide polymorphism associations from the meta-analysis were reassessed in 6 additional cohorts comprising 5767 subjects. RESULTS We identified 10 unique regions in which the combined association statistic was associated with total serum IgE levels (P<5.0×10(-6)) and the minor allele frequency was 5% or greater in 2 or more population groups. Variant rs9469220, corresponding to HLA-DQB1, was the single nucleotide polymorphism most significantly associated with serum total IgE levels when assessed in both the replication cohorts and the discovery and replication sets combined (P=.007 and 2.45×10(-7), respectively). In addition, findings from earlier genome-wide association studies were also validated in the current meta-analysis. CONCLUSION This meta-analysis independently identified a variant near HLA-DQB1 as a predictor of total serum IgE levels in multiple race-ethnic groups. This study also extends and confirms the findings of earlier genome-wide association analyses in African American and Latino subjects.
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Myers RA, Himes BE, Gignoux CR, Yang JJ, Gauderman WJ, Rebordosa C, Xie J, Torgerson DG, Levin AM, Baurley J, Graves PE, Mathias RA, Romieu I, Roth LA, Conti D, Avila L, Eng C, Vora H, LeNoir MA, Soto-Quiros M, Liu J, Celedón JC, Galanter JM, Farber HJ, Kumar R, Avila PC, Meade K, Serebrisky D, Thyne S, Rodriguez-Cintron W, Rodriguez-Santana JR, Borrell LN, Lemanske RF, Bleecker ER, Meyers DA, London SJ, Barnes KC, Raby BA, Martinez FD, Gilliland FD, Williams LK, Burchard EG, Weiss ST, Nicolae DL, Ober C. Further replication studies of the EVE Consortium meta-analysis identifies 2 asthma risk loci in European Americans. J Allergy Clin Immunol 2012; 130:1294-301. [PMID: 23040885 DOI: 10.1016/j.jaci.2012.07.054] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 07/27/2012] [Accepted: 07/31/2012] [Indexed: 11/26/2022]
Abstract
BACKGROUND Genome-wide association studies of asthma have implicated many genetic risk factors, with well-replicated associations at approximately 10 loci that account for only a small proportion of the genetic risk. OBJECTIVES We aimed to identify additional asthma risk loci by performing an extensive replication study of the results from the EVE Consortium meta-analysis. METHODS We selected 3186 single nucleotide polymorphisms for replication based on the P values from the EVE Consortium meta-analysis. These single nucleotide polymorphisms were genotyped in ethnically diverse replication samples from 9 different studies, totaling 7202 cases, 6426 controls, and 507 case-parent trios. Association analyses were conducted within each participating study, and the resulting test statistics were combined in a meta-analysis. RESULTS Two novel associations were replicated in European Americans: rs1061477 in the KLK3 gene on chromosome 19 (combined odds ratio = 1.18; 95% CI, 1.10-1.25) and rs9570077 (combined odds ratio =1.20; 95% CI, 1.12-1.29) on chromosome 13q21. We could not replicate any additional associations in the African Americans or Latinos. CONCLUSIONS This extended replication study identified 2 additional asthma risk loci in populations of European descent. The absence of additional loci for African Americans and Latinos highlights the difficulty in replicating associations in admixed populations.
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Breton CV, Salam MT, Wang X, Byun HM, Siegmund KD, Gilliland FD. Particulate matter, DNA methylation in nitric oxide synthase, and childhood respiratory disease. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:1320-6. [PMID: 22591701 PMCID: PMC3440108 DOI: 10.1289/ehp.1104439] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 05/16/2012] [Indexed: 05/21/2023]
Abstract
BACKGROUND Air pollutants have been associated with childhood asthma and wheeze. Epigenetic regulation of nitric oxide synthase--the gene responsible for nitric oxide production--may be affected by air pollutants and contribute to the pathogenesis of asthma and wheeze. OBJECTIVE Our goal was to investigate the association between air pollutants, DNA methylation, and respiratory outcomes in children. METHODS Given residential address and buccal sample collection date, we estimated 7-day, 1-month, 6-month, and 1-year cumulative average PM₂.₅ and PM₁₀ (particulate matter ≤ 2.5 and ≤ 10 µm aerodynamic diameter, respectively) exposures for 940 participants in the Children's Health Study. Methylation of 12 CpG sites in three NOS (nitric oxide synthase) genes was measured using a bisulfite-polymerase chain reaction Pyrosequencing assay. Beta regression models were used to estimate associations between air pollutants, percent DNA methylation, and respiratory outcomes. RESULTS A 5-µg/m³ increase in PM₂.₅ was associated with a 0.20% [95% confidence interval (CI): -0.32, -0.07] to 1.0% (95% CI: -1.61, -0.56) lower DNA methylation at NOS2A position 1, 0.06% (95% CI: -0.18, 0.06) to 0.58% (95% CI: -1.13, -0.02) lower methylation at position 2, and 0.34% (95% CI: -0.57, -0.11) to 0.89% (95% CI: -1.57, -0.21) lower methylation at position 3, depending on the length of exposure and CpG locus. One-year PM2.5 exposure was associated with 0.33% (95% CI: 0.01, 0.65) higher in average DNA methylation of 4 loci in the NOS2A CpG island. A 5-µg/m³ increase in 7-day and 1-year PM₂.₅ was associated with 0.6% (95% CI: 0.13, 0.99) and 2.8% (95% CI: 1.77, 3.75) higher NOS3 DNA methylation. No associations were observed for NOS1. PM₁₀ showed similar but weaker associations with DNA methylation in these genes. CONCLUSIONS PM₂.₅ exposure was associated with percent DNA methylation of several CpG loci in NOS genes, suggesting an epigenetic mechanism through which these pollutants may alter production of nitric oxide.
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Bradfield JP, Taal HR, Timpson NJ, Scherag A, Lecoeur C, Warrington NM, Hypponen E, Holst C, Valcarcel B, Thiering E, Salem RM, Schumacher FR, Cousminer DL, Sleiman PMA, Zhao J, Berkowitz RI, Vimaleswaran KS, Jarick I, Pennell CE, Evans DM, St Pourcain B, Berry DJ, Mook-Kanamori DO, Hofman A, Rivadeneira F, Uitterlinden AG, van Duijn CM, van der Valk RJP, de Jongste JC, Postma DS, Boomsma DI, Gauderman WJ, Hassanein MT, Lindgren CM, Mägi R, Boreham CAG, Neville CE, Moreno LA, Elliott P, Pouta A, Hartikainen AL, Li M, Raitakari O, Lehtimäki T, Eriksson JG, Palotie A, Dallongeville J, Das S, Deloukas P, McMahon G, Ring SM, Kemp JP, Buxton JL, Blakemore AIF, Bustamante M, Guxens M, Hirschhorn JN, Gillman MW, Kreiner-Møller E, Bisgaard H, Gilliland FD, Heinrich J, Wheeler E, Barroso I, O'Rahilly S, Meirhaeghe A, Sørensen TIA, Power C, Palmer LJ, Hinney A, Widen E, Farooqi IS, McCarthy MI, Froguel P, Meyre D, Hebebrand J, Jarvelin MR, Jaddoe VWV, Smith GD, Hakonarson H, Grant SFA. A genome-wide association meta-analysis identifies new childhood obesity loci. Nat Genet 2012; 44:526-31. [PMID: 22484627 PMCID: PMC3370100 DOI: 10.1038/ng.2247] [Citation(s) in RCA: 270] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 03/14/2012] [Indexed: 12/19/2022]
Abstract
Multiple genetic variants have been associated with adult obesity and a few with severe obesity in childhood; however, less progress has been made in establishing genetic influences on common early-onset obesity. We performed a North American, Australian and European collaborative meta-analysis of 14 studies consisting of 5,530 cases (≥95th percentile of body mass index (BMI)) and 8,318 controls (<50th percentile of BMI) of European ancestry. Taking forward the eight newly discovered signals yielding association with P < 5 × 10(-6) in nine independent data sets (2,818 cases and 4,083 controls), we observed two loci that yielded genome-wide significant combined P values near OLFM4 at 13q14 (rs9568856; P = 1.82 × 10(-9); odds ratio (OR) = 1.22) and within HOXB5 at 17q21 (rs9299; P = 3.54 × 10(-9); OR = 1.14). Both loci continued to show association when two extreme childhood obesity cohorts were included (2,214 cases and 2,674 controls). These two loci also yielded directionally consistent associations in a previous meta-analysis of adult BMI(1).
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Leng S, Stidley CA, Liu Y, Edlund CK, Willink RP, Han Y, Landi MT, Thun M, Picchi MA, Bruse SE, Crowell RE, Van Den Berg D, Caporaso NE, Amos CI, Siegfried JM, Tesfaigzi Y, Gilliland FD, Belinsky SA. Genetic determinants for promoter hypermethylation in the lungs of smokers: a candidate gene-based study. Cancer Res 2012; 72:707-15. [PMID: 22139380 PMCID: PMC3271143 DOI: 10.1158/0008-5472.can-11-3194] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The detection of tumor suppressor gene promoter methylation in sputum-derived exfoliated cells predicts early lung cancer. Here, we identified genetic determinants for this epigenetic process and examined their biologic effects on gene regulation. A two-stage approach involving discovery and replication was used to assess the association between promoter hypermethylation of a 12-gene panel and common variation in 40 genes involved in carcinogen metabolism, regulation of methylation, and DNA damage response in members of the Lovelace Smokers Cohort (N = 1,434). Molecular validation of three identified variants was conducted using primary bronchial epithelial cells. Association of study-wide significance (P < 8.2 × 10(-5)) was identified for rs1641511, rs3730859, and rs1883264 in TP53, LIG1, and BIK, respectively. These single-nucleotide polymorphisms (SNP) were significantly associated with altered expression of the corresponding genes in primary bronchial epithelial cells. In addition, rs3730859 in LIG1 was also moderately associated with increased risk for lung cancer among Caucasian smokers. Together, our findings suggest that genetic variation in DNA replication and apoptosis pathways impacts the propensity for gene promoter hypermethylation in the aerodigestive tract of smokers. The incorporation of genetic biomarkers for gene promoter hypermethylation with clinical and somatic markers may improve risk assessment models for lung cancer.
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Eckel SP, Berhane K, Salam MT, Rappaport EB, Linn WS, Bastain TM, Zhang Y, Lurmann F, Avol EL, Gilliland FD. Residential traffic-related pollution exposures and exhaled nitric oxide in the children's health study. ENVIRONMENTAL HEALTH PERSPECTIVES 2011; 119:1472-7. [PMID: 21708511 PMCID: PMC3230449 DOI: 10.1289/ehp.1103516] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 06/27/2011] [Indexed: 05/05/2023]
Abstract
BACKGROUND The fractional concentration of nitric oxide in exhaled air (FeNO) potentially detects airway inflammation related to air pollution exposure. Existing studies have not yet provided conclusive evidence on the association of FeNO with traffic-related pollution (TRP). OBJECTIVES We evaluated the association of FeNO with residential TRP exposure in a large cohort of children. METHODS We related FeNO measured on 2,143 children (ages 7-11 years) who participated in the Southern California Children's Health Study (CHS) to five classes of metrics of residential TRP: distances to freeways and major roads; length of all and local roads within circular buffers around the home; traffic densities within buffers; annual average line source dispersion modeled nitrogen oxides (NOx) from freeways and nonfreeway roads; and predicted annual average nitrogen oxide, nitrogen dioxide, and NOx from a model based on intracommunity sampling in the CHS. RESULTS In children with asthma, length of roads was positively associated with FeNO, with stronger associations in smaller buffers [46.7%; 95% confidence interval (CI), 14.3-88.4], 12.4% (95% CI, -8.8 to 38.4), and 4.1% (95% CI, -14.6 to 26.8) higher FeNO for 100-, 300-, and 1,000-m increases in the length of all roads in 50-, 100-, and 200-m buffers, respectively. Other TRP metrics were not significantly associated with FeNO, even though the study design was powered to detect exposures explaining as little as 0.4% of the variation in natural log-transformed FeNO (R2 = 0.004). CONCLUSION Length of road was the only indicator of residential TRP exposure associated with airway inflammation in children with asthma, as measured by FeNO.
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Torgerson DG, Ampleford EJ, Chiu GY, Gauderman WJ, Gignoux CR, Graves PE, Himes BE, Levin AM, Mathias RA, Hancock DB, Baurley JW, Eng C, Stern DA, Celedón JC, Rafaels N, Capurso D, Conti DV, Roth LA, Soto-Quiros M, Togias A, Li X, Myers RA, Romieu I, Van Den Berg DJ, Hu D, Hansel NN, Hernandez RD, Israel E, Salam MT, Galanter J, Avila PC, Avila L, Rodriquez-Santana JR, Chapela R, Rodriguez-Cintron W, Diette GB, Adkinson NF, Abel RA, Ross KD, Shi M, Faruque MU, Dunston GM, Watson HR, Mantese VJ, Ezurum SC, Liang L, Ruczinski I, Ford JG, Huntsman S, Chung KF, Vora H, Li X, Calhoun WJ, Castro M, Sienra-Monge JJ, del Rio-Navarro B, Deichmann KA, Heinzmann A, Wenzel SE, Busse WW, Gern JE, Lemanske RF, Beaty TH, Bleecker ER, Raby BA, Meyers DA, London SJ, Gilliland FD, Burchard EG, Martinez FD, Weiss ST, Williams LK, Barnes KC, Ober C, Nicolae DL. Meta-analysis of genome-wide association studies of asthma in ethnically diverse North American populations. Nat Genet 2011; 43:887-92. [PMID: 21804549 PMCID: PMC3445408 DOI: 10.1038/ng.888] [Citation(s) in RCA: 621] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 06/16/2011] [Indexed: 11/09/2022]
Abstract
Asthma is a common disease with a complex risk architecture including both genetic and environmental factors. We performed a meta-analysis of North American genome-wide association studies of asthma in 5,416 individuals with asthma (cases) including individuals of European American, African American or African Caribbean, and Latino ancestry, with replication in an additional 12,649 individuals from the same ethnic groups. We identified five susceptibility loci. Four were at previously reported loci on 17q21, near IL1RL1, TSLP and IL33, but we report for the first time, to our knowledge, that these loci are associated with asthma risk in three ethnic groups. In addition, we identified a new asthma susceptibility locus at PYHIN1, with the association being specific to individuals of African descent (P = 3.9 × 10(-9)). These results suggest that some asthma susceptibility loci are robust to differences in ancestry when sufficiently large samples sizes are investigated, and that ancestry-specific associations also contribute to the complex genetic architecture of asthma.
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Breton CV, Salam MT, Gilliland FD. Heritability and role for the environment in DNA methylation in AXL receptor tyrosine kinase. Epigenetics 2011; 6:895-8. [PMID: 21555911 DOI: 10.4161/epi.6.7.15768] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
DNA methylation in AXL, a receptor tyrosine kinase relevant in cancer and immune function, is reportedly highly heritable. We present evidence to suggest that heritability of DNA methylation in AXL is variable, dependent on population characteristics and cell type studied. Moreover, environmental exposures in utero, particularly exposure to maternal smoking, contributes to variation in DNA methylation of select CpG loci that can affect calculations of heritability. Children exposed to maternal smoking in utero had a 2.3% increase (95 % CI 0.3, 4.2) in DNA methylation in AXL, which was magnified in girls as compared to boys. These results present compelling evidence that environmental exposure to tobacco smoke during pregnancy may alter DNA methylation levels in subtle but potentially important ways, and that these changes are persistent years after birth.
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Breton CV, Byun HM, Wang X, Salam MT, Siegmund K, Gilliland FD. DNA methylation in the arginase-nitric oxide synthase pathway is associated with exhaled nitric oxide in children with asthma. Am J Respir Crit Care Med 2011; 184:191-7. [PMID: 21512169 DOI: 10.1164/rccm.201012-2029oc] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
RATIONALE Genetic variation in arginase (ARG) and nitric oxide synthase (NOS) has been associated with exhaled nitric oxide (FeNO) levels in children. Little is known about whether epigenetic variation in these genes modulates FeNO. OBJECTIVES To evaluate whether DNA methylation in ARG and NOS genes is associated with FeNO. METHODS A subset of 940 participants in the Children's Health Study were selected for this study. Children were eligible if they had FeNO measurements and buccal cells collected on the same day. CpG loci located in the promoter regions of NOS1, NOS2A, NOS3, ARG1, and ARG2 genes were analyzed. Multiple loci in each gene were evaluated individually and averaged together. DNA methylation was measured using a bisulfite-polymerase chain reaction pyrosequencing assay. Linear regression models were used to investigate the association between DNA methylation and FeNO and whether associations differed by asthma status. MEASUREMENTS AND MAIN RESULTS DNA methylation in ARG2 was significantly associated with FeNO. A 1% increase in average DNA methylation of ARG2 was associated with a 2.3% decrease in FeNO (95% confidence interval, -4 to -0.6). This association was significantly larger in children with asthma (%diff = -8.7%) than in children with no asthma (%diff = -1.6%; p(int) = 0.01). Differences in FeNO by asthma status were also observed for ARG1 (%diff(asthma) = -4.4%; %diff(non-asthma) = 0.3%; p(int) = 0.02). DNA methylation in NOS genes was not associated with FeNO. CONCLUSIONS DNA methylation in ARG1 and ARG2 is associated with FeNO in children with asthma and suggests a possible role for epigenetic regulation of nitric oxide production.
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Leng S, Stidley CA, Willink RP, Liu Y, Picchi MA, Berg DVD, Gilliland FD, Crowell RE, Belinsky SA. Abstract 2759: Association between genetic variations in DNA damage response pathways and risk for gene methylation in sputum from smokers. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-2759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The detection of gene promoter hypermethylation in sputum containing exfoliated epithelial cells is a promising biomarker for detecting early incident lung cancer. Therefore, identifying factors that influence the propensity for this epigenetic process throughout the respiratory epithelium is a high priority. The genes and the pathways they modulate underlying the inter-individual susceptibility to DNA methylation remain largely elusive. Accumulating evidence from our group and others implicate DNA damage as an important step in the acquisition of de novo methylation. We hypothesized that genetic variations in genes (n=66) involved in carcinogen metabolism and DNA damage response, including DNA damage repair, cell cycle control, apoptosis, and methylation related pathways will be associated with gene methylation in sputum from lung-cancer free smokers. Three databases including HapMap Stage I database, University of Southern California DNA repair and Children Pulmonary Function Development Oligo Pool Assay (OPA) database, and NIBC dbSNPs database were used to select a comprehensive set of SNPs (OPA1, n=1536) to capture the major genetic variations in these genes. A pilot study for testing the association between these SNPs and risk for methylation was conducted in a subset of people (n=261) selected from Lovelace Smokers Cohort (LSR) based on their methylation index (8-gene panel). Two gene-based analyses were conducted to rank the genes and 683 tagging SNPs from the top 42 genes were selected based on the OPA1 and the HapMap Stage II databases and genotyped in all people (n=1177) with methylation data (12-gene panel) in baseline sputum samples in LSR. The effect of SNPs was tested under an additive inheritance model. A reproducible association was identified in SNPs from the TP53, GSTP1, LIG1, CASP8, BOK, and PMAIP1 genes between the pilot study and the entire study. Ongoing functional studies reveled an association between genotype and expression of LIG1 in bronchial epithelial cells from smokers. This study identified six genes involved in carcinogen detoxification and DNA damage response that were associated with risk for gene methylation in sputum from smokers. (Supported from National Cancer Institute R01 CA097356 and the State of New Mexico as a direct appropriation from the Tobacco Settlement Fund)
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2759. doi:10.1158/1538-7445.AM2011-2759
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