PADI2 and rheumatoid arthritis: In blood cells, DAXX, HLA-A, HLA-C, HLA-DPB1, HLA-DQA1, HLA-DQB1, PADI2, PHF19, RNASET2 and VARS2 were differentially expressed between RA cases and controls according to GSE15573 and GSE17755 data (P = 1.31 × 10− 9, 2.82 × 10− 7, 5.34 × 10− 6, 3.86 × 10− 13, 9.37 × 10− 11, 2.62 × 10− 25, 6.23 × 10− 20, 1.82 × 10− 4, 4.82 × 10− 5 and 1.09 × 10− 13, respectively).