PRTN3 and rheumatoid arthritis: JAK: Janus kinase; MHRA: Medicines and Healthcare products Regulatory Agency; RA: rheumatoid arthritis; ACPA: anti-citrullinated protein antibody; RF: rheumatoid factor; DAS-28 CRP: Disease Activity Score in 28 joints using C-reactive protein; csDMARDs: conventional synthetic disease-modifying antirheumatic drugs