PRTN3 and arthritic joint disease: In a study of 524 early arthritis patients, seven variables: (i) symptom duration at first visit, (ii) early morning stiffness (EMS), (iii) arthritis in three or more joints, (iv) bilateral compression pain in the metatarsophalangeal (MTP) joints, (v) rheumatoid factor (RF) positivity, (vi) anti-citrullinated protein antibodies (ACPA) positivity, and (vii) the presence of erosions (hands/feet) were modeled for predictivity and shown to reliably discriminate between self- limiting, persistent non-erosive, and persistent erosive arthritis at 2-year follow-up.