PTPN22 and juvenile idiopathic arthritis: We acknowledge that with the current sample size, this study was insufficiently powered to identify common variants having only modest effect sizes; therefore, we were unable to replicate genome-wide-significant associations found for several previously known JIA-predisposing genes, such as PTPN22, STAT4, PTPN2, ANKRD55, and IL2/IL21 (4).