Single-cell transcriptome-wide association analysis reveals epithelial cell-specific genetic susceptibility to colorectal cancer

Bulk-tissue transcriptome-wide association studies (TWAS) have identified colorectal cancer (CRC) susceptibility genes, but cell-type-specific regulatory mechanisms remain poorly understood. Here, we performed single-cell TWAS integrating matched germline genotypes and single-cell transcriptomes from normal colorectal mucosa (381 donors) and polyps (84 donors), cell-type-specific chromatin accessibility, and GWAS from 132,261 cases and 1,752,398 controls. We identified 546 gene-cell-type associations implicating 347 candidate susceptibility genes across seven normal and nine polyp epithelial populations, including 213 previously unreported genes, with 74% exhibiting cell-type-specific associations. Integrated co-expression and ChIP-seq analyses revealed distinct TF-risk gene networks, highlighting GATA6, MAX and RAD21 in normal mucosa, and TFAP4- and CEBPB-associated networks in premalignant polyp populations. Further multi-omics analyses supported dysregulation of 233 genes (67%), while drug-target analyses identified 63 potentially druggable genes. DepMap and CRISPR Cas9 analyses implicated 35 genes in CRC cell viability. These findings reveal cell-type-specific susceptibility mechanisms and prioritize candidate therapeutic targets for CRC prevention.