PTPN22 and juvenile idiopathic arthritis: Two SNPs that mapped to the PTPN22 region, which were almost perfectly correlated with each other but which showed only modest correlation with the known PTPN22 functional variant (rs2476601; r2 = 0.27 for rs1217407 and R620W), were weakly associated with JIA (P = 0.015 for rs1217407 and P = 0.014 for rs1217380).