Anti-citrullinated filaggrin antibodies have been shown to be useful as a prognostic marker in patients with early RA (124), while in general, the anti-citrullinated protein antibodies (ACPA) are found in 60% of RA patients and are believed to be a critical hallmark in the pathogenesis of RA (125). Here, PRTN3 is linked to rheumatoid arthritis.