The data indicate that 77% (20/26) ACPA positive FDR (as determined by CCP3 positivity) recognize the Cit39-40 H4 peptide, albeit in lower titers than in RA patients, in whom it was recognized by 92% (83/90) of CCP3 positive serum samples. The gene discussed is AGBL3; the disease is rheumatoid arthritis.