RA activity was in remission (disease activity score (DAS) 28-CRP: 1.32) and laboratory investigations revealed white blood cells (WBCs) of 4600/mm3, lactate dehydrogenase (LDH) of 326 U/L, C-reactive protein (CRP) of 0.17 mg/dL, soluble IL-2 receptor (sIL-2R) of 1705 U/mL (reference 122–496 U/mL), RF of 35 IU/mL, and anti-cyclic citrullinated peptide antibody (ACPA) of 67.4 U/mL. Here, PRTN3 is linked to rheumatoid arthritis.