Crohn’s disease and ulcerative colitis, the two common forms of inflammatory bowel disease (IBD), affect over 2.5 million people of European ancestry, with rising prevalence in other populations1. Genome-wide association studies and subsequent meta-analyses of these two diseases2, 3 as separate phenotypes have implicated previously unsuspected mechanisms, such as autophagy4, in their pathogenesis and showed that some IBD loci are shared with other inflammatory diseases5. Here we expand on the knowledge of relevant pathways by undertaking a meta-analysis of Crohn’s disease and ulcerative colitis genome-wide association scans, followed by extensive validation of significant findings, with a combined total of more than 75,000 cases and controls. We identify 71 new associations, for a total of 163 IBD loci, that meet genome-wide significance thresholds. Most loci contribute to both phenotypes, and both directional (consistently favouring one allele over the course of human history) and balancing (favouring the retention of both alleles within populations) selection effects are evident. Many IBD loci are also implicated in other immune-mediated disorders, most notably with ankylosing spondylitis and psoriasis. We also observe considerable overlap between susceptibility loci for IBD and mycobacterial infection. Gene co-expression network analysis emphasizes this relationship, with pathways shared between host responses to mycobacteria and those predisposing to IBD.
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- Supplementary Information (10.3M)
This file contains Supplementary Text, Supplementary Figures 1-12, full legends for Supplementary Tables 1-6, Supplementary References and a list of IBD Genetics Consortium members – see Supplementary Contents for details.
- Supplementary Tables (357K)
This zipped files contains Supplementary Tables 1-6 as follows: 1 shows the GWAS and Immunochip samples used in the study; 2 contains complete details of 163 IBD loci; 3 contains details of disease overlaps with IMD, PID and MSMD described in section 2 of the methods; 4 contains detailed enrichment statistics for all GO terms and canonical pathways; 5 contains the signals of selection at IBD loci; 6 shows enrichment scores for genes in IBD loci within co-expression modules. Supplementary Table 2, which is contained in this zipped file, has been replaced, as there was an error in the original file. In the ‘Detailed assoc stats’ tab, the ‘IC risk’ and ‘IC_nonrisk’ column labels were inadvertently switched. In addition, clarification of the cohort used to determine the odds ratio (OR) shown in the ‘Detailed assoc stats’ and ‘Main Table’ tabs has been included. This file was replaced online on 31 January 2013.
- Supplementary Data (722K)
This zipped file is a Cytoscape file for the macrophage enriched, omental adipose Bayesian network.