PRTN3 and rheumatoid arthritis: A consequence is that patients with small joint arthritis and high titres of ACPA and/or rheumatoid factor (RF) are identified, whereas to fulfil the newer classification criteria, patients with seronegative RA need to present with higher degree of inflammation and more extensive joint engagement compared to the ACR-1987 criteria.5 The changes between different classification criteria have and will have impact on the phenotype of RA, its prognosis as well as on treatment choices.