Meta-analysis of GWAS data identifies genetic risk factors for inflammatory bowel disease in 125,992 individuals

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medRxiv Published May 18, 2026 Medically reviewed May 18, 2026 Study authors: Fachal, L.; Zhang, R.; Gettler, K.; Haritunians, T.; Cleynen, I.; Stevens, C. R.; Zhang, Q.; Tastad,… DOI ↗ By Dr. Julia Lee, PhD · Oncology, Genomics & Drug Development

Key Takeaway

Note that genetic analysis supports new biological mechanisms but limits mechanistic interpretation and therapeutic translation.

This meta-analysis review synthesizes genome-wide association study data from a multi-ancestry population comprising 125,992 individuals with IBD and more than 1.2 million controls. The primary goal was the identification of independent association signals, resolution of causal variants, and prioritisation of candidate effector genes. The analysis covered Crohn's disease, ulcerative colitis, and inflammatory bowel disease broadly.

The study identified 619 independent association signals, of which 374 were novel, located at 420 IBD regions. These signals account for 77-80% of SNP-based heritability. Additionally, 81 high-confidence variants were resolved, with 41 not previously reported. The analysis prioritized 664 candidate effector genes across 341 signals, including 390 newly implicated IBD genes.

Subtype specificity was observed in 39% of the signals. The study supported a causal effect of decreased high-density lipoprotein on Crohn's disease risk based on latent causal modelling. The authors note that causal variants, effector genes, and relevant cellular contexts remain difficult to resolve, which limits mechanistic interpretation and therapeutic translation. No adverse events or safety data were reported.

The practice relevance lies in revealing new biological mechanisms and candidate therapeutic targets supported by human genetics. Clinicians should interpret these genetic findings as supportive of biological mechanisms rather than direct clinical interventions, given the current limitations in resolving causal variants.

Study Details

Study typeMeta analysis

EvidenceLevel 1

PublishedMay 2026

View Original Abstract ↓

Inflammatory bowel diseases (IBD), principally Crohn's disease (CD) and ulcerative colitis (UC), are common chronic disorders involving inflammation and often progressive tissue damage. Genome-wide association studies have mapped many risk signals, but the causal variants, effector genes and relevant cellular contexts remain difficult to resolve, limiting mechanistic interpretation and therapeutic translation. Here we performed a multi-ancestry GWAS meta-analysis of 125,992 individuals with IBD and more than 1.2 million controls, identifying 619 independent association signals (374 novel) at 420 IBD regions that account for 77-80% of SNP-based heritability. Fine-mapping resolved 81 high-confidence variants, 41 not previously reported. Although most signals were shared between CD and UC, 39% showed subtype specificity, with UC signals showing stronger enrichment in functional annotations from intestinal epithelial, secretory and enteroendocrine cells, and CD showing stronger genetic correlations with circulating inflammatory biomarkers, including C-reactive protein and glycoprotein acetylation. Latent causal modelling supported a causal effect of decreased high-density lipoprotein on CD risk. By integrating bulk and single-cell eQTL and pQTL resources using colocalisation and Mendelian randomisation, together with coding-variant evidence from exome sequencing, we prioritised 664 candidate effector genes across 341 signals, including 390 newly implicated IBD genes, revealing new biological mechanisms and candidate therapeutic targets supported by human genetics.