FAM209B and rheumatoid arthritis: From the TF–mRNA–miRNA regulatory network we predicted, it can be seen that there are some common transcription factors (such as ESR1) and miRNAs (including hsa-miR-671-5p, hsa-miR-939-5p, hsa-miR-6752-5p, hsa-miR-6858-5p, hsa-miR-6824-5p, hsa-miR-6765-5p, and hsa-miR-6089) between FAM209B and PTGES. Among them, ESR1 was a hub gene in many autoimmune diseases (57), including type 1 diabetes (58), systemic lupus erythematosus (59), and rheumatoid arthritis (60).