PRTN3 and rheumatoid arthritis: Furthermore, the rs7574865 and rs10181656 loci in the STAT4 gene were associated with anti-cyclic citrullinated peptide (ACPA)-positive RA (81–84), and a rare missense variant in the exon of STAT4, rs140675301A, has also been shown to increase the risk of seropositive RA (59).