Integrative pathway genomics of lung function and airflow obstruction

Chronic respiratory disorders are important contributors to the global burden of disease. Genome-wide association studies (GWASs) of lung function measures have identified several trait-associated loci, but explain only a modest portion of the phenotypic variability. We postulated that integrating pathway-based methods with GWASs of pulmonary function and airflow obstruction would identify a broader repertoire of genes and processes influencing these traits. We performed two independent GWASs of lung function and applied gene set enrichment analysis to one of the studies and validated the results using the second GWAS. We identified 131 significantly enriched gene sets associated with lung function and clustered them into larger biological modules involved in diverse processes including development, immunity, cell signalling, proliferation and arachidonic acid. We found that enrichment of gene sets was not driven by GWAS-significant variants or loci, but instead by those with less stringent association P-values. Next, we applied pathway enrichment analysis to a meta-analysed GWAS of airflow obstruction. We identified several biologic modules that functionally overlapped with those associated with pulmonary function. However, differences were also noted, including enrichment of extracellular matrix (ECM) processes specifically in the airflow obstruction study. Network analysis of the ECM module implicated a candidate gene, matrix metalloproteinase 10 (MMP10), as a putative disease target. We used a knockout mouse model to functionally validate MMP10’s role in influencing lung’s susceptibility to cigarette smoke-induced emphysema. By integrating pathway analysis with population-based genomics, we unravelled biologic processes underlying pulmonary function traits and identified a candidate gene for obstructive lung disease

New blood pressure associated loci identified in meta-analyses of 475,000 individuals

Background—Genome-wide association studies have recently identified >400 loci that harbor DNA sequence variants that influence blood pressure (BP). Our earlier studies identified and validated 56 single nucleotide variants (SNVs) associated with BP from meta-analyses of exome chip genotype data. An additional 100 variants yielded suggestive evidence of association. Methods and Results—Here, we augment the sample with 140 886 European individuals from the UK Biobank, in whom 77 of the 100 suggestive SNVs were available for association analysis with systolic BP or diastolic BP or pulse pressure. We performed 2 meta-analyses, one in individuals of European, South Asian, African, and Hispanic descent (pan-ancestry, ≈475 000), and the other in the subset of individuals of European descent (≈423 000). Twenty-one SNVs were genome-wide significant (P<5×10−8) for BP, of which 4 are new BP loci: rs9678851 (missense, SLC4A1AP), rs7437940 (AFAP1), rs13303 (missense, STAB1), and rs1055144 (7p15.2). In addition, we identified a potentially independent novel BP-associated SNV, rs3416322 (missense, SYNPO2L) at a known locus, uncorrelated with the previously reported SNVs. Two SNVs are associated with expression levels of nearby genes, and SNVs at 3 loci are associated with other traits. One SNV with a minor allele frequency <0.01, (rs3025380 at DBH) was genome-wide significant. Conclusions—We report 4 novel loci associated with BP regulation, and 1 independent variant at an established BP locus. This analysis highlights several candidate genes with variation that alter protein function or gene expression for potential follow-up

Genomic copy number variation, human health, and disease

Despite the long recognised effects of chromosomal structural abnormalities and completion of the Human Genome Project, much of the structural variation in the genome has gone unrecognised until recently. Deletions and duplications of DNA strands of between a few hundred bp and several million bp—collectively referred to as copy number variants—are now known to be widespread. Since 2007, rigorous and adequately powered genome-wide association studies based on single nucleotide polymorphisms have yielded replicated associations to several common diseases. Some copy number variants explain rare, previously uncharacterised disorders, and they are now expected to explain some of the genetic contribution to common diseases. We review efforts to map copy number variants and discuss present and future prospects for assessment of their relation to human health and disease

Translational genomics and precision medicine: Moving from the lab to the clinic

Translational genomics aims to improve human health by building on discoveries made through genetics research and applying them in the clinical setting. This progress has been made possible by technological advances in genomics and analytics and by the digital revolution. Such advances should enable the development of prognostic markers, tailored interventions, and the design of prophylactic preventive approaches. We are at the cusp of predicting disease risk for some disorders by means of polygenic risk scores integrated with classical epidemiological risk factors. This should lead to better risk stratification and clinical decision-making. A deeper understanding of the link between genome-wide sequence and association with well-characterized phenotypes will empower the development of biomarkers to aid diagnosis, inform disease progression trajectories, and allow better targeting of treatments to those patients most likely to respond

Human exome-chip meta-analysis identifies novel genetic loci associated with smoking behaviour

Smoking is a major risk factor for many diseases, including common respiratory disorders such as chronic obstructive pulmonary disease. Previous GWASs have been successful in identifying 13 common SNPs associated with smoking behaviour. Meta-analysing summary data from up to 33 cohorts, we have carried out an association study between the SNPs found on the exome-chip (n ≈250k SNPs), which predominantly assays rare putatively functional variants, and four traits: Smoking Initiation (n≈80k), Smoking Cessation (n≈41.5k), Cigarettes Per Day (n≈26.5k) and Pack Years (n≈33k). In addition to identifying previously reported signals with regards to smoking behaviour, we have identified SNPs in 5 novel regions, including a rare variant on chromosome 16 (MAF=0.01%). The previously identified SNPs fall within CHRNA5 (rs16969968, missense), CHRNA3 (rs938682, intronic) and IREB2 (rs13180, synonymous) – which are all located at the 15q25 locus. We are currently initiating follow-up studies; and if replicated, the novel loci identified in this study will facilitate understanding the genetic aetiology of smoking behaviour and may lead to identification of drug targets of potential relevance to smoking cessation

The UK10K project identifies rare variants in health and disease

The contribution of rare and low-frequency variants to human traits is largely unexplored. Here we describe insights from sequencing whole genomes (low read depth, 7×) or exomes (high read depth, 80×) of nearly 10,000 individuals from population-based and disease collections. In extensively phenotyped cohorts we characterize over 24 million novel sequence variants, generate a highly accurate imputation reference panel and identify novel alleles associated with levels of triglycerides (APOB), adiponectin (ADIPOQ) and low-density lipoprotein cholesterol (LDLR and RGAG1) from single-marker and rare variant aggregation tests. We describe population structure and functional annotation of rare and low-frequency variants, use the data to estimate the benefits of sequencing for association studies, and summarize lessons from disease-specific collections. Finally, we make available an extensive resource, including individual-level genetic and phenotypic data and web-based tools to facilitate the exploration of association results

Genetic analysis of over one million people identifies 535 novel loci for blood pressure

High blood pressure is a highly heritable and modifiable risk factor for cardiovascular disease. We report the largest genetic association study of blood pressure traits (systolic, diastolic, pulse pressure) to date in over one million people of European ancestry. We identify 535 novel blood pressure loci that not only offer new biological insights into blood pressure regulation but also reveal shared genetic architecture between blood pressure and lifestyle exposures. Our findings identify new biological pathways for blood pressure regulation with potential for improved cardiovascular disease prevention in the future

Human CCL3L1 copy number variation, gene expression, and the role of the CCL3L1-CCR5 axis in lung function

Background: The CCL3L1-CCR5 signaling axis is important in a number of inflammatory responses, including macrophage function, and T-cell-dependent immune responses. Small molecule CCR5 antagonists exist, including the approved antiretroviral drug maraviroc, and therapeutic monoclonal antibodies are in development. Repositioning of drugs and targets into new disease areas can accelerate the availability of new therapies and substantially reduce costs. As it has been shown that drug targets with genetic evidence supporting their involvement in the disease are more likely to be successful in clinical development, using genetic association studies to identify new target repurposing opportunities could be fruitful. Here we investigate the potential of perturbation of the CCL3L1-CCR5 axis as treatment for respiratory disease. Europeans typically carry between 0 and 5 copies of CCL3L1 and this multi-allelic variation is not detected by widely used genome-wide single nucleotide polymorphism studies.  Methods: We directly measured the complex structural variation of CCL3L1 using the Paralogue Ratio Test and imputed (with validation) CCR5del32 genotypes in 5,000 individuals from UK Biobank, selected from the extremes of the lung function distribution, and analysed DNA and RNAseq data for CCL3L1 from the 1000 Genomes Project. Results: We confirmed the gene dosage effect of CCL3L1 copy number on CCL3L1 mRNA expression levels.  We found no evidence for association of CCL3L1 copy number or CCR5del32 genotype with lung function. Conclusions: These results suggest that repositioning CCR5 antagonists is unlikely to be successful for the treatment of airflow obstruction

Novel idiopathic pulmonary fibrosis susceptibility variants revealed by deep sequencing

Background: Specific common and rare single nucleotide variants (SNVs) increase the likelihood of developing sporadic idiopathic pulmonary fibrosis (IPF). We performed target enriched sequencing on three loci previously identified by a genome-wide association study to gain a deeper understanding of the full spectrum of IPF genetic risk and performed a two-stage case-control association study. Methods: A total of 1.7 Mb of DNA from 181 IPF patients was deep sequenced (100X) across 11p15.5, 14q21.3, and 17q21.31 loci. Comparisons were performed against 501 unrelated controls and replication studies were assessed in 3,968 subjects. Results: Thirty-six SNVs were associated with IPF susceptibility in the discovery stage (p<5.0x10-8). After meta-analysis, the strongest association corresponded to rs35705950 (p=9.27x10-57) located upstream from the mucin 5B (MUC5B) gene. Additionally, a novel association was found for two co-inherited low-frequency SNVs (<5%) in MUC5AC gene, predicting a missense amino acid change in mucin 5AC (lowest p=2.27x10-22). Conditional and haplotype analyses in 11p15.5 supported the existence of additional contribution of MUC5AC variants to IPF risk. Conclusions: This study reinforces the significant IPF associations of these loci and implicates MUC5AC as another key player in IPF susceptibility

Slamming the door on trade policy discretion? : the WTO Appellate Body’s ruling on market distortions and production costs in EU-Biodiesel (Argentina)

This paper presents a legal-economic analysis of the Appellate Body’s decision that the WTO’s Anti-Dumping Agreement (ADA) precludes countries from taking into account government-created price distortions of major inputs when calculating anti-dumping duties, made in EU-Biodiesel (Argentina). In this case, the EU made adjustments to the price of biodiesel’s principal input – soybeans – in determining the cost of production of biodiesel in Argentina. The adjustment was made based on the uncontested finding that the price of soybeans in Argentina was distorted by the existence of an export tax scheme that resulted in artificially low soybean prices. The Appellate Body found that the EU was not permitted to take tax policy-induced price distortions into account in calculating dumping margins. We analyze the economic rationale for Argentina’s export tax system, distortions in biodiesel markets in Argentina and the EU, and the remaining trade policy options for addressing distorted international prices. We also assess whether existing subsidies disciplines would be more effective in addressing this problem and conclude that they would not