Quantification P. gingivalis, anti-RgpA and anti-PPAD antibodies;clinical RA assessment: DAS28;laboratory variables: RF, hsCRP, ESR, antibodies to ACPA-IgG/IgA;periodontal assessments: plaque index, GI, BOP, pocket depth, CAL. The gene discussed is PRTN3; the disease is rheumatoid arthritis.