The dysregulated PAD activity is observed in numerous inflammatory diseases including rheumatoid arthritis (RA), Alzheimer’s disease, atherosclerosis, and periodontal diseases (PDs) (Vossenaar et al., 2003; Ishigami et al., 2005; Kinloch et al., 2008; Jones et al., 2009). This evidence concerns the gene PADI4 and rheumatoid arthritis.