PRTN3 and rheumatoid arthritis: To begin to address this question, we profiled serum FAs and oxylipins in an established cohort of at-risk ACPA-positive first-degree relatives (FDR) of RA patients (N = 31), some of whom developed RA (N = 4), and compared their profile to ACPA-negative FDR from the same population (N = 10).<h4>Methods</h4>Gas chromatography (GC) was used for FA quantitation.