Compared with the ACPA - FDR group, the ACPA + FDR, including those who progressed into inflammatory arthritis, displayed higher levels of LOX-derived oxylipins.<h4>Conclusion</h4>ACPA seropositivity in otherwise unaffected individuals at-risk for developing future RA based on family history (FDR) is associated with alterations in the serum oxylipin profile that suggests dysregulated LOX activity. This evidence concerns the gene PRTN3 and rheumatoid arthritis.