Although citrullinated filaggrin is not present in the inflammatory synovium of RA patients, several citrullinated auto-antigens, including citrullinated fibrinogen, vimentin, type II collagen, and alpha-enolase, have been reported as target antigens of ACPAs in the synovia of RA patients [9-14]. The gene discussed is ENO1; the disease is rheumatoid arthritis.