Aberrant and excessive PAD4 expression is seen in a variety of chronic inflammatory diseases including rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis and vascular thrombotic diseases (deep venous thrombosis, atherothrombosis, atherosclerosis and myeloproliferative neoplasms) 16-18. Here, PADI4 is linked to rheumatoid arthritis.