IL18R1 and rheumatoid arthritis: According to the KEGG pathway enrichment analysis, pathways associated with RA inflammatory process were enriched to rheumatoid arthritis and osteoclast differentiation, with cytokine–cytokine receptor interaction, cell adhesion molecules (CAMs), antigen processing and presentation, natural killer cell-mediated cytotoxicity, and other pathways related to antigen immune response being the most significantly enriched.