Several chromosomal regions have been identified using family-based linkage analysis to contain genes contributing to the development of asthma and allergic disorders. One of these regions, chromosome 2q32-q33, contains a gene cluster containing CFLAR, CASP10 and CASP8. These genes regulate the extrinsic apoptosis pathway utilized by several types of immune and structural cells that have been implicated in the pathogenesis of asthma.
To assess the role of genetic variation in CFLAR, CASP10 and CASP8 in asthma and related phenotypes in individuals of diverse ethnic backgrounds.
We tested 26 single nucleotide polymorphisms (SNPs) in the CFLAR, CASP10 and CASP8 gene cluster for association with asthma and related phenotypes in African-American, non-Hispanic whites, and Hispanic case–control populations (cases, N = 517, controls, N = 644).
Five CASP10 SNPS were associated with forced expiratory volume in 1 s (FEV1)/forced expiration volume capacity (FVC) in the African-American subjects with asthma (P = 0.0009–0.047). Nine SNPs, seven in CASP10 and two in CASP8, were also associated with the degree of bronchial hyperresponsiveness (BHR) (as determined by PC20) in race-specific analysis, predominately in the Non-Hispanic white cases. Two SNPs, rs6750157 in CASP10 and rs1045485 in CASP8 were modestly associated with asthma in the African-American (P = 0.025) and Hispanic (P = 0.033) populations, respectively.
These data suggest a role for CASP10 as a potential modifier of the asthma phenotype, specifically with measures of airway obstruction and BHR.
asthma; bronchial hyperresponsiveness; CASP10; chromosome 2q; FEV1/FVC
DNA methylation is one of several epigenetic mechanisms that contribute to the regulation of gene expression; however, the extent to which methylation of CpG dinucleotides correlates with gene expression at the genome-wide level is still largely unknown. Using purified primary monocytes from subjects in a large community-based cohort (n = 1264), we characterized methylation (>485 000 CpG sites) and mRNA expression (>48K transcripts) and carried out genome-wide association analyses of 8370 expression phenotypes. We identified 11 203 potential cis-acting CpG loci whose degree of methylation was associated with gene expression (eMS) at a false discovery rate threshold of 0.001. Most of the associations were consistent in effect size and direction of effect across sex and three ethnicities. Contrary to expectation, these eMS were not predominately enriched in promoter regions, or CpG islands, but rather in the 3′ UTR, gene bodies, CpG shores or ‘offshore’ sites, and both positive and negative correlations between methylation and expression were observed across all locations. eMS were enriched for regions predicted to be regulatory by ENCODE (Encyclopedia of DNA Elements) data in multiple cell types, particularly enhancers. One of the strongest association signals detected (P < 2.2 × 10−308) was a methylation probe (cg17005068) in the promoter/enhancer region of the glutathione S-transferase theta 1 gene (GSTT1, encoding the detoxification enzyme) with GSTT1 mRNA expression. Our study provides a detailed description of the epigenetic architecture in human monocytes and its relationship to gene expression. These data may help prioritize interrogation of biologically relevant methylation loci and provide new insights into the epigenetic basis of human health and diseases.
Recent meta-analyses of genome-wide association studies in general populations of European descent have identified 28 loci for lung function.
We sought to identify novel lung function loci specifically for asthma and to confirm lung function loci identified in general populations.
Genome-wide association studies of lung function (percent predicted FEV1 [ppFEV1], percent predicted forced vital capacity, and FEV1/forced vital capacity ratio) were performed in 4 white populations of European descent (n = 1544), followed by meta-analyses.
Seven of 28 previously identified lung function loci (HHIP, FAM13A, THSD4, GSTCD, NOTCH4-AGER, RARB, and ZNF323) identified in general populations were confirmed at single nucleotide polymorphism (SNP) levels (P < .05). Four of 32 loci (IL12A, IL12RB1, STAT4, and IRF2) associated with ppFEV1 (P < 10−4) belong to the TH1 or IL-12 cytokine family pathway. By using a linear additive model, these 4 TH1 pathway SNPs cumulatively explained 2.9% to 7.8% of the variance in ppFEV1 values in 4 populations (P = 3 × 10−11). Genetic scores of these 4 SNPs were associated with ppFEV1 values (P = 2 × 10−7) and the American Thoracic Society severe asthma classification (P = .005) in the Severe Asthma Research Program population. TH2 pathway genes (IL13, TSLP, IL33, and IL1RL1) conferring asthma susceptibility were not associated with lung function.
Genes involved in airway structure/remodeling are associated with lung function in both general populations and asthmatic subjects. TH1 pathway genes involved in anti-virus/bacterial infection and inflammation modify lung function in asthmatic subjects. Genes associated with lung function that might affect asthma severity are distinct from those genes associated with asthma susceptibility.
Lung function; FEV1; asthma; TH1; IL12A; IL12RB1; STAT4; IRF2
Levels of omega-6 (n-6) and omega-3 (n-3), long chain polyunsaturated fatty acids (LcPUFAs) such as arachidonic acid (AA; 20∶4, n-6), eicosapentaenoic acid (EPA; 20∶5, n-3) and docosahexaenoic acid (DHA; 22∶6, n-3) impact a wide range of biological activities, including immune signaling, inflammation, and brain development and function. Two desaturase steps (Δ6, encoded by FADS2 and Δ5, encoded by FADS1) are rate limiting in the conversion of dietary essential 18 carbon PUFAs (18C-PUFAs) such as LA (18∶2, n-6) to AA and α-linolenic acid (ALA, 18∶3, n-3) to EPA and DHA. GWAS and candidate gene studies have consistently identified genetic variants within FADS1 and FADS2 as determinants of desaturase efficiencies and levels of LcPUFAs in circulating, cellular and breast milk lipids. Importantly, these same variants are documented determinants of important cardiovascular disease risk factors (total, LDL, and HDL cholesterol, triglycerides, CRP and proinflammatory eicosanoids). FADS1 and FADS2 lie head-to-head (5′ to 5′) in a cluster configuration on chromosome 11 (11q12.2). There is considerable linkage disequilibrium (LD) in this region, where multiple SNPs display association with LcPUFA levels. For instance, rs174537, located ∼15 kb downstream of FADS1, is associated with both FADS1 desaturase activity and with circulating AA levels (p-value for AA levels = 5.95×10−46) in humans. To determine if DNA methylation variation impacts FADS activities, we performed genome-wide allele-specific methylation (ASM) with rs174537 in 144 human liver samples. This approach identified highly significant ASM with CpG sites between FADS1 and FADS2 in a putative enhancer signature region, leading to the hypothesis that the phenotypic associations of rs174537 are likely due to methylation differences. In support of this hypothesis, methylation levels of the most significant probe were strongly associated with FADS1 and, to a lesser degree, FADS2 activities.
Representative samples are required for ethical, valid, and useful health research. Yet, recruiting participants, especially from historically underserved communities, can be challenging. This paper presents findings from in-depth interviews with 40 mothers about factors that might influence their willingness to participate or allow their children to participate in medical research. Saliency analysis organizes the findings. Frequent and important salient themes about research participation included concerns that it might cause participants harm, hope that participants might gain a health benefit, and recognition that time and transportation resources could limit participation. Ultimately, we propose that a theoretical model, such as the Theory of Planned Behavior (TPB), will facilitate more systematic evaluation of effective methods for recruitment and retention of participants in medical research. Future research should explore the utility of such a model for development of effective recruitment and retention strategies.
Health research; recruitment; women; children; underserved populations
This study investigated the association of copy number variants (CNVs) in type 2 diabetes (T2D) and T2D-associated end-stage renal disease (ESRD) in African Americans. Using the Affymetrix 6.0 array, >900,000 CNV probes spanning the genome were interrogated in 965 African Americans with T2D-ESRD and 1029 non-diabetic African American controls. Previously identified and novel CNVs were separately analyzed and were evaluated for insertion/deletion status and then used as predictors in a logistic regression model to test for association. One common CNV insertion on chromosome 1 was significantly associated with T2D-ESRD (p=6.17×10−5, OR=1.63) after multiple comparison correction. This CNV region encompasses the genes AMY2A and AMY2B, which encode amylase isoenzymes produced by the pancreas. Additional common and novel CNVs approaching significance with disease were also detected. These exploratory results require further replication but suggest the involvement of the AMY2A/AMY2B CNV in T2D and/or T2D-ESRD, and indicate that CNVs may contribute to susceptibility for these diseases.
Copy number variation; African Americans; Diabetic nephropathy; End-stage renal disease; Genome-wide association study; Type 2 diabetes
QT is a risk factor for sudden cardiac death (SCD). A genome wide association study identified NOS1AP variants associated with QT, which have been replicated in predominantly Caucasian (CAU) populations. We used MESA to examine association of QT with NOS1AP variants in an ethnically diverse cohort.
Twenty-eight tagging SNPs spanning NOS1AP were genotyped in 2847 MESA participants (approximately equal numbers of CAU, African-Americans (AFA), Hispanics (HIS) and Chinese (CHN)), age 45–84 years, without cardiovascular disease. QT was measured using 12-lead ECG. Associations between QT and NOS1AP variants were evaluated using linear regression, adjusted for heart rate, age, gender, and field center stratified by ancestry, using an additive inheritance model. Ancestry informative markers (AIMs) and principal components using AIMs were used as additional covariates.
More NOS1AP SNPs were associated with QT in CAU than the other races. In CAU, each copy of rs1932933 risk allele was associated with an increase in QT (4.9msec, p= 7.20×10-7). Significant associations in CAU and HIS were located at the 5′ end, while associations in CHN were located at the 3′ end.
NOS1AP variants were associated with QT in CAU, with weaker evidence for selected variants in HIS and CHN. Location of significant SNPs varied across ancestry. We identified possible novel associations at the 3′ end of NOS1AP, where we observed significant association with QT in CHN only. Genotyping within these regions may determine functional variants affecting QT and SCD risk. Further investigations are needed across ethnically diverse population cohorts.
Genetics; Electrocardiography; Arrhythmia; Electrophysiology
Genome-wide association studies (GWAS) have identified 36 loci associated with body mass index (BMI), predominantly in populations of European ancestry. We conducted a meta-analysis to examine the association of >3.2 million SNPs with BMI in 39,144 men and women of African ancestry, and followed up the most significant associations in an additional 32,268 individuals of African ancestry. We identified one novel locus at 5q33 (GALNT10, rs7708584, p=3.4×10−11) and another at 7p15 when combined with data from the Giant consortium (MIR148A/NFE2L3, rs10261878, p=1.2×10−10). We also found suggestive evidence of an association at a third locus at 6q16 in the African ancestry sample (KLHL32, rs974417, p=6.9×10−8). Thirty-two of the 36 previously established BMI variants displayed directionally consistent effect estimates in our GWAS (binomial p=9.7×10−7), of which five reached genome-wide significance. These findings provide strong support for shared BMI loci across populations as well as for the utility of studying ancestrally diverse populations.
Chromosome 22q11.2 deletion syndrome (22q11DS) is associated with neurocognitive impairments. The neural substrates of cognitive impairments in 22q11DS remain poorly understood. Because the corpus callosum (CC) is found to be abnormal in a variety of neurodevelopmental disorders, we obtained volumetric measurements of the CC and its subregions, examined the relationship between these regions and neurocognition and selected genotypes within candidate genes in the 22q11.2 interval in 59 children with 22q11DS and 53 control subjects. The total CC, splenium and genu were significantly larger in children with 22q11DS and the enlargement was associated with better neurocognitive functioning in the 22q11DS group, suggestive of a compensatory increase in the CC volumes. The expected age-related increase in the volume of the CC was not seen in children with 22q11DS, indicative of dysmaturation of the CC in these children. The increased volumes in the genu, splenium and total CC in the 22q11DS group were associated with polymorphisms within the candidate genes: COMT (rs4680), ZDHHC8 (rs175174) and UFD1L (rs5992403). These findings indicate that alterations in the CC volume in children with 22q11DS are associated with cognition and specific genotypes in the 22q11.2 interval.
chromosome 22q11.2 deletion syndrome; velocardiofacial syndrome; corpus callosum; neurocognition; schizophrenia
Genome-wide association studies (GWASs) of asthma have consistently implicated the ORM1-like 3 and gasdermin B (ORMDL3-GSDMB), IL33, IL-1 receptor–like 1 and IL-18 receptor 1 (IL1RL1-IL18R1), RAD50-IL13, thymic stromal lymphopoietin and WD repeat domain 36 region (TSLP-WDR36), and HLA-DR/DQ regions.
A GWAS of asthma was performed in a non-Hispanic white population.
A GWAS was performed in 813 Severe Asthma Research Program/Collaborative Studies on the Genetics of Asthma/Chicago Asthma Genetics Study cases and 1564 control subjects. The GWAS results were compared with those of the published GWASs of autoimmune diseases.
Multiple single nucleotide polymorphisms in the TNFAIP3 interacting protein 1 (TNIP1) gene, which interacts with TNFAIP3 and inhibits the TNF-α–induced nuclear factor κB inflammation pathway, were associated with asthma: rs1422673 (P = 3.44 × 10−7) and rs10036748 (P = 1.41 × 10−6, r2 = 0.67). rs1422673 was also associated with asthma in the published GABRIEL (P = .018) and EVE (P = 1.31 × 10−5) studies. The minor allele T of rs20541 in IL13 is the risk allele for asthma but the protective allele for psoriasis. The minor allele T of rs2395185 in HLA-DRA is the risk allele for asthma but the protective allele for ulcerative colitis. The minor allele A of rs2872507 in GSDMB is the protective allele for asthma but the risk allele for rheumatoid arthritis, Crohn disease, and ulcerative colitis. The T allele of rs10036748 in the TNIP1 gene is the minor protective allele for asthma but the minor or major risk allele for systemic lupus erythematosus and systemic sclerosis in non-Hispanic white or Chinese subjects, respectively.
Our study suggests that single nucleotide polymorphisms associated with both asthma and autoimmune diseases might have opposite effects on immunopathogenesis. (J Allergy Clin Immunol 2012;130:861-8.)
Asthma; genetics; genome-wide association study; TNFAIP3 interacting protein 1
Genetic variants that contribute to asthma susceptibility may be present at varying frequencies in different populations, which is an important consideration and advantage for performing genetic association studies in admixed populations.
To identify asthma-associated loci in African Americans.
We compared local African and European ancestry estimated from dense single nucleotide polymorphism (SNP) genotype data in African American adults with asthma and non-asthmatic controls. Allelic tests of association were performed within the candidate regions identified, correcting for local European admixture.
We identified a significant ancestry association peak on chromosomes 6q. Allelic tests for association within this region identified a SNP (rs1361549) on 6q14.1 that was associated with asthma exclusively in African Americans with local European admixture (OR=2.2). The risk allele is common in Europe (42% in the HapMap CEU) but absent in West Africa (0% in the HapMap YRI), suggesting the allele is present in African Americans due to recent European admixture. We replicated our findings in Puerto Ricans and similarly found that the signal of association is largely specific to individuals who are heterozygous for African and non-African ancestry at 6q14.1. However, we found no evidence for association in European Americans or in Puerto Ricans in the absence of local African ancestry, suggesting that the association with asthma at rs1361549 is due to an environmental or genetic interaction.
We identified a novel asthma-associated locus that is relevant to admixed populations with African ancestry, and highlight the importance of considering local ancestry in genetic association studies of admixed populations.
asthma; population structure; genome-wide association study; admixture mapping; ancestry association testing; admixed populations; African Americans; Puerto Ricans
We have conducted a GWAS in a Caucasian cohort of juvenile idiopathic arthritis (JIA) patients and have previously published findings limited to autoimmune loci shared with other diseases. The goal of this study was to identify novel JIA predisposing loci using genome-wide approaches.
The Discovery cohort consisted of Caucasian JIA cases (814) and local controls (658) genotyped on the Affymetrix SNP 6.0 Array along with 2400 out-of-study controls. A replication study consisted of 10 SNPs genotyped in 1744 cases and 7010 controls from the US and Europe.
Analysis within the Discovery cohort provided evidence of associations at 3q13 within C3orf1 and near CD80 (rs4688011, OR=1.37, P=1.88×10−6), and 10q21 near the gene JMJD1C [rs6479891, odds ratio (OR) =1.59, P=6.1×10−8; rs12411988, OR=1.57, P=1.16×10−7 and rs10995450, OR = 1.31, P=6.74×10−5]. Meta-analysis continued to provide evidence for association for these 4 SNPs (rs4688011, P=3.6×10−7, rs6479891, P=4.33×10−5; rs12411988, P=2.71×10−5; and rs10995450, 5.39×10−5;). Gene expression data from 68 JIA cases and 23 local controls showed cis eQTL associations for C3orf1 SNP rs4688011 (P=0.024 or P=0.034, depending on probe set) and the JMJD1C SNPs rs6479891 and rs12411988 (P=0.01 and P=0.008, respectively). A variance component liability model estimated that common SNP variation accounts for ~1/3 of JIA susceptibility.
Genetic association results and correlated gene expression findings provide evidence of association at 3q13 and 10q21 for JIA and offer novel genes as plausible candidates in disease pathology.
The IL6R SNP rs4129267 has recently been identified as an asthma susceptibility locus in subjects of European ancestry but has not been characterized with respect to asthma severity. The SNP rs4129267 is in linkage disequilibrium (r2=1) with the IL6R coding SNP rs2228145 (Asp358Ala). This IL6R coding change increases IL6 receptor shedding and promotes IL6 transsignaling.
To evaluate the IL6R SNP rs2228145 with respect to asthma severity phenotypes.
The IL6R SNP rs2228145 was evaluated in subjects of European ancestry with asthma from the Severe Asthma Research Program (SARP). Lung function associations were replicated in the Collaborative Study on the Genetics of Asthma (CSGA) cohort. Serum soluble IL6 receptor (sIL6R) levels were measured in subjects from SARP. Immunohistochemistry was used to qualitatively evaluate IL6R protein expression in BAL cells and endobronchial biopsies.
The minor C allele of IL6R SNP rs2228145 was associated with lower ppFEV1 in the SARP cohort (p=0.005), the CSGA cohort (0.008), and in combined cohort analysis (p=0.003). Additional associations with ppFVC, FEV1/FVC, and PC20 were observed. The rs2228145 C allele (Ala358) was more frequent in severe asthma phenotypic clusters. Elevated serum sIL6R was associated with lower ppFEV1 (p=0.02) and lower ppFVC (p=0.008) (N=146). IL6R protein expression was observed in BAL macrophages, airway epithelium, vascular endothelium, and airway smooth muscle.
The IL6R coding SNP rs2228145 (Asp358Ala) is a potential modifier of lung function in asthma and may identify subjects at risk for more severe asthma. IL6 transsignaling may have a pathogenic role in the lung.
soluble interleukin 6 receptor; sIL6R; interleukin 6; IL6; asthma; pulmonary lung function; severe asthma; IL6 transsignaling; genetic variation; SNP rs2228145
asthma genetics; atopy; C11orf30; LRRC32; total serum IgE levels
Carotid-femoral pulse wave velocity (CFPWV) is a heritable measure of aortic stiffness that is strongly associated with increased risk for major cardiovascular disease events.
Methods and Results
We conducted a meta-analysis of genome-wide association data in 9 community-based European ancestry cohorts consisting of 20,634 participants. Results were replicated in 2 additional European ancestry cohorts involving 5,306 participants. Based on a preliminary analysis of 6 cohorts, we identified a locus on chromosome 14 in the 3′-BCL11B gene desert that is associated with CFPWV (rs7152623, minor allele frequency = 0.42, beta=−0.075±0.012 SD/allele, P = 2.8 x 10−10; replication beta=−0.086±0.020 SD/allele, P = 1.4 x 10−6). Combined results for rs7152623 from 11 cohorts gave beta=−0.076±0.010 SD/allele, P=3.1x10−15. The association persisted when adjusted for mean arterial pressure (beta=−0.060±0.009 SD/allele, P = 1.0 x 10−11). Results were consistent in younger (<55 years, 6 cohorts, N=13,914, beta=−0.081±0.014 SD/allele, P = 2.3 x 10−9) and older (9 cohorts, N=12,026, beta=−0.061±0.014 SD/allele, P=9.4x10−6) participants. In separate meta-analyses, the locus was associated with increased risk for coronary artery disease (hazard ratio [HR]=1.05, confidence interval [CI]=1.02 to 1.08, P=0.0013) and heart failure (HR=1.10, CI=1.03 to 1.16, P=0.004).
Common genetic variation in a locus in the BCL11B gene desert that is thought to harbor one or more gene enhancers is associated with higher CFPWV and increased risk for cardiovascular disease. Elucidation of the role this novel locus plays in aortic stiffness may facilitate development of therapeutic interventions that limit aortic stiffening and related cardiovascular disease events.
aorta; arterial stiffness; pulse wave velocity; genetics; cardiovascular disease
Coronary artery calcification (CAC) detected by computed tomography is a non-invasive measure of coronary atherosclerosis, that underlies most cases of myocardial infarction (MI). We aimed to identify common genetic variants associated with CAC and further investigate their associations with MI.
Methods and Results
Computed tomography was used to assess quantity of CAC. A meta-analysis of genome-wide association studies for CAC was carried out in 9,961 men and women from five independent community-based cohorts, with replication in three additional independent cohorts (n=6,032). We examined the top single nucleotide polymorphisms (SNPs) associated with CAC quantity for association with MI in multiple large genome-wide association studies of MI. Genome-wide significant associations with CAC for SNPs on chromosome 9p21 near CDKN2A and CDKN2B (top SNP: rs1333049, P=7.58×10−19) and 6p24 (top SNP: rs9349379, within the PHACTR1 gene, P=2.65×10−11) replicated for CAC and for MI. Additionally, there is evidence for concordance of SNP associations with both CAC and with MI at a number of other loci, including 3q22 (MRAS gene), 13q34 (COL4A1/COL4A2 genes), and 1p13 (SORT1 gene).
SNPs in the 9p21 and PHACTR1 gene loci were strongly associated with CAC and MI, and there are suggestive associations with both CAC and MI of SNPs in additional loci. Multiple genetic loci are associated with development of both underlying coronary atherosclerosis and clinical events.
cardiac computed tomography; coronary artery calcification; coronary atherosclerosis; genome-wide association studies; myocardial infarction
DNA from buccal brush samples is being used for high-throughput analyses in a variety of applications, but the impact of sample type on genotyping success and downstream statistical analysis remains unclear. The objective of the current study was to determine laboratory predictors of genotyping failure among buccal DNA samples, and to evaluate the successfully genotyped results with respect to analytic quality control metrics. Sample and genotyping characteristics were compared between buccal and blood samples collected in the population-based Genetic and Environmental Risk Factors for Hemorrhagic Stroke (GERFHS) study (https://gerfhs.phs.wfubmc.edu/public/index.cfm).
Seven-hundred eight (708) buccal and 142 blood DNA samples were analyzed for laboratory-based and analysis metrics. Overall genotyping failure rates were not statistically different between buccal (11.3%) and blood (7.0%, p = 0.18) samples; however, both the Contrast Quality Control (cQC) rate and the dynamic model (DM) call rates were lower among buccal DNA samples (p < 0.0001). The ratio of double-stranded to total DNA (ds/total ratio) in the buccal samples was the only laboratory characteristic predicting sample success (p < 0.0001). A threshold of at least 34% ds/total DNA provided specificity of 98.7% with a 90.5% negative predictive value for eliminating probable failures. After genotyping, median sample call rates (99.1% vs. 99.4%, p < 0.0001) and heterozygosity rates (25.6% vs. 25.7%, p = 0.006) were lower for buccal versus blood DNA samples, respectively, but absolute differences were small. Minor allele frequency differences from HapMap were smaller for buccal than blood samples, and both sample types demonstrated tight genotyping clusters, even for rare alleles.
We identified a buccal sample characteristic, a ratio of ds/total DNA <34%, which distinguished buccal DNA samples likely to fail high-throughput genotyping. Applying this threshold, the quality of final genotyping resulting from buccal samples is somewhat lower, but compares favorably to blood. Caution is warranted if cases and controls have different sample types, but buccal samples provide comparable results to blood samples in large-scale genotyping analyses.
Buccal; Blood; DNA; Quality; Minor allele frequency (MAF); Genetic
Respiratory health is an important component of the ability to perform physically demanding work. We assessed the prevalence of self-reported respiratory symptoms among Latino farmworkers primarily engaged in crop production and investigated work activities as risk factors for respiratory symptoms. During June-September 2008, 122 farmworkers completed up to three interviewer-administered questionnaires. We estimated the associations between work activities and wheezing symptoms using alternating logistic regression, controlling for age and smoking. At the first data collection, 24% (n=29) of farmworkers reported ever wheezing and 8% reported wheezing within the past month. Though not statistically significant, the odds of wheezing were elevated for individuals who reported performing tobacco-related work in the last three days. The odds were decreased among individuals who reported harvesting activities (odds ratio: 0.3, 95% confidence interval: 0.1, 1.0). Among Latino farmworkers, respiratory symptoms may be associated with work activities.
agriculture; asthma; epidemiology; occupational lung disease; respiratory diseases
Two recent large meta-analyses of genome-wide association studies of lung function in general populations of European descent identified 11 candidate genes/regions. The importance of these genes in lung function in whites and African Americans with asthma is unknown.
To determine if genes that regulate lung function in general populations are associated with lung function abnormalities in subjects with asthma from different racial groups.
SNPs were tested in five asthma populations (n = 1,441) for association with pulmonary function and meta-analysis was performed across populations. The SNPs with the highest significance were then tested for association with bronchodilator reversibility and bronchial hyperresponsiveness to methacholine (BHR). A joint analysis of consistently replicated SNPs was performed to predict lung function in asthma.
Hedgehog interacting protein (HHIP) on chromosome 4q31 was associated with lung function in all five populations, rs1512288: Pmeta = 9.62E-05 and 3.23E-05 for ppFEV1 and ppFVC, respectively. The SNPs in HHIP were also associated with reversibility (P < 0.05) but not BHR. Because of differences in linkage disequilibrium in the African-American subjects, the most relevant SNPs in HHIP were identified. A subset of normal lung function genes, including HHIP, family with sequence similarity 13, member A (FAM13A), and patched homolog 1 (PTCH1), together predict lung function abnormalities, a measure of severity in whites and African Americans with asthma.
A subset of the genes, including HHIP, which regulate lung function in general populations are associated with abnormal lung function in asthma in non-Hispanic whites and African Americans.
Asthma; Genetics; Asthma severity; Meta-analysis; FEV1; FVC; FEV1/FVC; HHIP; FAM13A; PTCH1
Nutritional interventions are important alternatives for reducing the prevalence of many chronic diseases. Soy is a good source of protein that contains isoflavones, including genistein and daidzein, and may alter the risk of obesity, Type 2 diabetes, osteoporosis, cardiovascular disease, and reproductive cancers. We have shown previously in nonhuman primates that soy protein containing isoflavones leads to improved body weight, insulin sensitivity, lipid profiles, and atherosclerosis compared to protein without soy isoflavones (casein), and does not increase the risk of cancer. Since genistein has been shown to alter DNA methylation, we compared the methylation profiles of cynomolgus monkeys, from multiple tissues, eating two high-fat, typical American diets (TAD) with similar macronutrient contents, with or without soy protein. DNA methylation status was successfully determined for 80.6% of the probes in at least one tissue using Illumina's HumanMethylation27 BeadChip. Overall methylation increased in liver and muscle tissue when monkeys switched from the TAD-soy to the TAD-casein diets. Genes involved in epigenetic processes, specifically homeobox genes (HOXA5, HOXA11, and HOXB1), and ABCG5 were among those that changed between diets. These data support the use of the HumanMethylation27 BeadChip in cynomolgus monkeys and identify epigenetic changes associated with dietary interventions with soy protein that may potentially affect the etiology of complex diseases.
Asthma is a heterogeneous disease that is caused by the interaction of genetic susceptibility with environmental influences. Genome-wide association studies (GWAS) represent a powerful approach to investigate the association of DNA variants with disease susceptibility. To date, few GWAS for asthma have been reported.
GWAS was performed on a population of severe or difficult-to-treat asthmatics to identify genes that are involved in the pathogenesis of asthma.
292,443 SNPs were tested for association with asthma in 473 TENOR cases and 1,892 Illumina general population controls. Asthma-related quantitative traits (total serum IgE, FEV1, FVC, and FEV1/FVC) were also tested in identified candidate regions in 473 TENOR cases and 363 phenotyped controls without a history of asthma to further analyze GWAS results. Imputation was performed in identified candidate regions for analysis with denser SNP coverage.
Multiple SNPs in the RAD50-IL13 region on chromosome 5q31.1 were associated with asthma: rs2244012 in intron 2 of RAD50 (P = 3.04E-07). The HLA-DR/DQ region on chromosome 6p21.3 was also associated with asthma: rs1063355 in the 3’ UTR of HLA-DQB1 (P = 9.55E-06). Imputation identified several significant SNPs in the TH2 locus control region (LCR) 3’ of RAD50. Imputation also identified a more significant SNP, rs3998159 (P = 1.45E-06), between HLA-DQB1 and HLA-DQA2.
This GWAS confirmed the important role of TH2 cytokine and antigen presentation genes in asthma at a genome-wide level and the importance of additional investigation of these two regions to delineate their structural complexity and biologic function in the development of asthma.
Asthma; GWAS; RAD50; IL13; HLA-DQB1; TENOR
A high degree of inter-individual variability in plasma lipid level response to hormone therapy (HT) has been reported. Variations in the oestrogen receptor α gene (ESR1) and in genes involved in lipid metabolism may explain some of the variability in response to HT.
Postmenopausal Caucasian women (N=208) participating in a placebo-controlled randomized trial of 3.2 years of hormone therapy (HT).
Plasma triglycerides (TG), remnant lipoprotein cholesterol (RLP-C), and high-density lipoprotein cholesterol (HDL-C) levels and HDL subpopulations were assessed at baseline and at follow-up. Single nucleotide polymorphisms (SNPs) in ESR1 and in the ATP binding cassette A1 (ABCA1), cholesteryl ester transfer protein (CETP), hepatic lipase (LIPC), lipoprotein lipase (LPL), and scavenger receptor class B type I (SRB1) genes were assessed for their association with baseline plasma levels and HT-related changes in levels of RLP-C and HDL subpopulations.
Carriers of the ESR1 PvuII or IVS1-1505 variants had lower plasma TG concentrations and higher plasma HDL-C and α-1 and preα-1 HDL particle levels at baseline and showed greater increases in HDL-C, apo A-I and α-1 particle levels after HT than wild-type carriers. Carriers of the N291S and D9N variants in the LPL gene had significantly higher remnant lipoproteins and lower α-2 HDL particle levels at baseline. The CETP TaqIB SNP was a significant determinant of baseline plasma HDL-C and HDL subpopulation profile.
SNPs in ESR1, CETP and LPL had significant effects on baseline plasma levels of TG-rich and HDL subpopulations. With the exception of ESR1 SNPs, variation in genes involved in lipid metabolism has a very modest effect on lipoprotein response to HT.
high-density lipoprotein; remnant lipoproteins; single nucleotide polymorphism hormone therapy
Rationale: Asthma is a chronic inflammatory airway disease that affects more than 300 million individuals worldwide. Asthma is caused by interaction of genetic and environmental factors. Bronchial hyperresponsiveness (BHR) is a hallmark of asthma and results from increased sensitivity of the airways to physical or chemical stimulants. BHR and asthma are linked to chromosome 5q31-q33.
Objectives: To identify a gene for BHR on chromosome 5q31-q33.
Methods: In 200 Dutch families with asthma, linkage analysis and fine mapping were performed, and the Protocadherin 1 gene (PCDH1) was identified. PCDH1 was resequenced in 96 subjects from ethnically diverse populations to identify novel sequence variants. Subsequent replication studies were undertaken in seven populations from The Netherlands, the United Kingdom, and the United States, including two general population samples, two family samples, and three case-control samples. PCDH1 mRNA and protein expression was investigated using polymerase chain reaction, Western blotting, and immunohistochemistry.
Measurements and Main Results: In seven out of eight populations (n = 6,168) from The Netherlands, United Kingdom, and United States, PCHD1 gene variants were significantly associated with BHR (P values, 0.005–0.05) This association was present in both families with asthma and general populations. PCDH1 mRNA and protein were expressed in airway epithelial cells and in macrophages.
Conclusions: PCDH1 is a novel gene for BHR in adults and children. The identification of PCDH1 as a BHR susceptibility gene may suggest that a structural defect in the integrity of the airway epithelium, the first line of defense against inhaled substances, contributes to the development of BHR.
bronchial hyperresponsiveness; asthma genetics; protocadherin-1; cell adhesion; airway epithelium
Background and Purpose
Migraine with aura is a risk factor for ischemic stroke but the mechanism by which these disorders are associated remains unclear. Both disorders exhibit familial clustering, which may imply a genetic influence on migraine and stroke risk. Genes encoding for endothelial function are promising candidate genes for migraine and stroke susceptibility because of the importance of endothelial function in regulating vascular tone and cerebral blood flow.
Using data from the Stroke Prevention in Young Women (SPYW) study, a population-based case-control study including 297 women aged 15–49 years with ischemic stroke and 422 women without stroke, we evaluated whether polymorphisms in genes regulating endothelial function, including endothelin-1 (EDN), endothelin receptor type B (EDNRB), and nitric oxide synthase-3 (NOS3), confer susceptibility to migraine and stroke.
EDN SNPs rs1800542 and rs10478723 were associated with increased stroke susceptibility in Caucasians, (OR = 2.1 (95% CI, 1.1 to 4.2) and OR = 2.2 (95% CI, 1.1 to 4.4); p = 0.02 and 0.02, respectively) as were EDNRB SNPs rs4885493 and rs10507875, (OR = 1.7 (95% CI, 1.1 to 2.7) and OR = 2.4 (95% CI, 1.4 to 4.3); p = 0.01 and 0.002, respectively). Only one of the tested SNPs (NOS3 - rs3918166) was associated with both migraine and stroke.
In our study population, variants in EDN and EDNRB were associated with stroke susceptibility in Caucasian but not in African-American women. We found no evidence that these genes mediate the association between migraine and stroke.