PTPN22 and juvenile idiopathic arthritis: Several contemporary JIA GWAS studies also built upon the findings of the Wellcome Trust Case Control Consortium Study to add both human leukocyte antigen (HLA) and non-HLA loci to the list, for which the latter included genes involved in T cell regulation and signaling; STAT4, TRAF1/C5, PTPN22, PTPN2, CD80, and JMJDC1 (6, 8–10).