Multidimensional dissection of shared genetic susceptibility in ulcerative colitis and colorectal cancer: novel insights from integrative single-cell and multi-omics analysis

BACKGROUND: Ulcerative colitis (UC) patients carry a 2.5-fold increased risk of colorectal cancer (CRC), yet the shared multi-scale genetic architecture remains poorly understood. We constructed an integrative framework across tissue, cellular, and variant levels to systematically dissect the pathogenic evolution of this comorbidity across spatiotemporal dimensions. METHODS: We integrated GWAS data from 100,204 CRC cases and 12,160 UC patients with tissue-specific MAGMA enrichment, embryonic spatial mapping (gsMap), and multidimensional single-cell prioritization (ECLIPSER, CELLECT, scDRS). We further resolved cell-specific co-expression patterns using hdWGCNA and identified high-confidence causal variants and genes through Bayesian fine-mapping (eCAVIAR, fastenloc) and Open4Gene analysis. RESULTS: Genetic susceptibility for both diseases was significantly enriched in the terminal ileum and transverse colon, anchored to E16.5 embryonic gut programs. CD4 + T cells emerged as the core immune hub in UC, exhibiting profound immunometabolic polarization (Th17/IL-17 axis and Warburg effect), while progenitors were identified as the primary cellular origin for CRC malignancy. Pathological progression was characterized by a transition from chronic inflammatory stress toward p53-mediated genomic instability, epithelial-mesenchymal transition (EMT), and vascular remodeling. We prioritized Tier 1 candidate genes-ARPC5, PTGER4, CIB1, PREX1, and S100A10-as key mediators of the comorbidity association between inflammation and cancer. CONCLUSIONS: These findings partially support a "genetic programming-microenvironment triggering" hypothesis, where regional vulnerabilities established by embryonic developmental programs are activated by postnatal insults, though its broad applicability warrants caution. This study provides a comprehensive multi-scale molecular framework for understanding UC-CRC comorbidity, offering potential targets for risk stratification and therapeutic intervention.