PRTN3 and rheumatoid arthritis: Rheumatoid arthritis (RA) is an incurable chronic inflammatory autoimmune disease that affects about 0.5–1% of the general population worldwide and is characterized by joint swelling, pain, the presence of autoantibodies (rheumatoid factor and anti-citrullinated protein antibodies (ACPA)), and subclinical signs of inflammation that result in aggressive synovitis and destruction of joint cartilage and bone [1,2].