Objective: Historically, it has been shown that rheumatoid arthritis (RA) and periodontitis (PE) share pathophysiological similarities and possibly a genetic background. In order to elucidate the genetic background between both diseases, we evaluated the distributions of five SNPs genotypes and all the possible haplotypes composed in subjects with isolated RA, PE, combined diseases and healthy controls.
Materials and methods: The study population consisted of 280 Mexican subjects. Genomic DNA was isolated from buccal epithelial cells collected by cheek scrapings and analyzed for the determination of the following SNPs: IL-1α + 4845 (rs17561), IL-1α -889 (rs1800587), IL-1β + 3954 (rs1143634), IL-1β -511(rs16944) and TNF-α -308 (rs1800629).
Results: After adjustment for age, sex and smoking status, multiple logistic regression analysis revealed a no significant association in the genotype frequencies of TNF-α -308 and IL-1α + 4845 SNPs. Otherwise a significant association was observed in IL-1β + 3954 and IL-1β -511 (p < 0.05) while IL-1α -889 was of borderline statistical significance (p = 0.054). Also, we found three negative associated haplotypes with PE: IL-1α + 4845 G/IL-1β -511 A, IL-1β + 3954 C/IL-1β -511 A and interestingly IL-1α -889 C/IL-1β -511 A also with a positive association with RA.
Conclusions: Some genotypes and haplotypes are associated with the diseases. But it seems that the genetic background of the association between RA and PE needs to be explored deeper.
Keywords: Cytokine SNPs; genetics; haplotypes.