Testing for Rheumatoid Factor (RF) and/or anti-citrullinated peptide antibodies (ACPA) should be performed in the evaluation of UPIA patients, as these factors are predictive of Rheumatoid Arthritis (RA) diagnosis and prognosis, although negative tests do not exclude progression to RA (2–4). This evidence concerns the gene PRTN3 and rheumatoid arthritis.