The study has two aims: 1) to evaluate the association of IL-17 polymorphism rs2275913 with RA severity and 2) to evaluate if this particular SNP is associated with susceptibility for RA in Mexican patients.
Seventy-six RA patients and ninety-four healthy controls were included in the study. RA patients were evaluated according to DAS 28. Treatment with DMARD'S was prescribed and radiological damage was evaluated according to the Larsen method. A case-control study was used. Oral epithelial cells were obtained as source for genetic material. DNA was amplified using PCR. Subsequently, a RFLP was carried out. Finally, in order to confirm the IL-17 SNP rs2275913 presence, direct sequencing of the DNA was performed.
A significant difference was observed between the RA patients and controls when the prevalence of IL-17 SNP rs2275913 was compared. There was a statistically significant disparity among the two groups with an OR of 5.6 (95%CI 1.5 - 20.9, P=<0.01). In this study was observed that the RA patients who were positive for the IL-17 polymorphism rs2275913 required 3 DMARDs to control the disease compared to 32% of the patients who were negative for the IL-17 polymorphism rs2275913, OR 6.6 (95%CI 1.6 - 27.0, P<0.01).
This study draws two main conclusions: 1) The presence of IL-17 polymorphism rs2275913 is closely related to a more severe form of the disease and as a result, a higher number of DMARDs required to control it, 2) The presence of IL-17 polymorphism rs2275913 may confer a risk of developing RA in Mexican carriers.