The PTPN22 (W620) risk allele shows a dominant effect in regulating autoreactive B cells even before the onset of autoimmunity, which might be associated with altered BCR signaling and upregulation of genes that promote B-cell responses such as CD40, TNF receptor-associated factor 1 (TRAF1), and IRF5 [134]. Here, PTPN22 is linked to Autoimmunity.