AbstractBackgroundRheumatoid arthritis (RA) and periodontitis (PD) are proven to share common risk markers, including genetic factors. In the present study we focused on genetic variants inPTPN22(rs2476601),PADI4 (rs2240340),CTLA4genes (rs3087243) and its impact on RA and PD.Materials and methodsIn the study 111 RA patients and 256 systemically healthy controls were involved. A subdivision of patients and controls was carried out according the severity of periodontitis (no/level 1 PD vs. level 2 PD).ResultsI. Evaluating the genetic impact on the occurrence of RA the T allele of rs2476601 (PTPN22)(bivariate:p < 0.001; multivariate:p = 0.018) and T allele of rs2240340 (PADI4) (bivariate:p = 0.006; multivariate:p = 0.070) were associated with an increased vulnerability to RA.II. Investigating the genetic influence on level 2 PD the T allele of rs2476601 (PTPN22)was shown to be associated with a higher susceptibility to PD within the RA group (bivariate: p = 0.043; multivariate:p = 0.024).III. The T allele of rs2476601 (PTPN22)was proven to be a significant marker of RA and level 2 PD comorbidity (bivariate:p < 0.001; multivariate:p = 0.028).ConclusionsThese results support the thesis that genetic variations may represent a possible link between PD and RA. The study increases knowledge about disease-specific and cross-disease genetic pattern.