HLA-DRB1 and inflammatory bowel disease: The signal transduction secondary cluster for G protein-coupled receptor signaling pathway contained the most IBD-unique eGenes, which included multiple genes associated with immune response (CTSS, HLA-DRB1, IFNGR2, PARK7, TNFRSF14), and FERMT1, which is involved in integrin signaling, an important mechanism for maintaining intestinal homeostasis64,65.