PTPN22 and inflammatory bowel disease: The most prominent genes are IL23A, TNFAIP3-interacting protein 1 (TNIP1), ERAP1, ERAP2, non-receptor tyrosine-protein kinase (TYK2), signal transducer and activator of transcription 4 (STAT4), interleukin 12 B (IL12B), RUNX3, toll-like receptor 4 (TLR4), interleukin 13 (IL13), IL23R, TRAF3 interacting protein 2 (TRAF3IP2), and protein tyrosine phosphatase, non-receptor type 22 (PTPN22)—some of them shared with other diseases, such as AS, IBD, ReA, RA, and systemic lupus erythematosus.