PRTN3 and rheumatoid arthritis: The variant DR3 gene as examined by the presence of the polymorphism d was found in 15 of 611 (2.45%) anti-citrullinated protein antibody (ACPA)-positive patients with RA, 15 of 538 (2.79%) ACPA- and rheumatoid factor-positive patients with RA, and 1 of 138 (0.72%) ACPA-negative patients with RA.