In conclusion, this study suggests that individuals with periodontitis carrying the minor alleles of PADI2 SNPs rs2057094, rs2076616 or rs2235912 may be at increased risk of anti-CCP-negative RA irrespective of smoking status and at increased risk of anti-CCP-positive RA if they have a history of smoking. This evidence concerns the gene PADI2 and rheumatoid arthritis.