Association of Interleukin-6-174 G/C Gene Promotor Polymorphism with Rheumatoid Arthritis in Adolescence Age Group: A Case-control Study

Introduction: Rheumatoid Arthritis (RA) is a chronic autoimmune disease with unknown pathogenesis. The disease is multifactorial, however, the exact causes of the occurrence, as well as the targets of the autoimmune process, are unknown. Genes candidate for a predisposition to RA are cytokine genes. Of the cytokines, IL-6 is considered a key mediator of systemic and localized inflammation in RA. Aim: The comparative analysis of the frequency distribution of alleles and genotypes IL-6 -174G/C polymorphism in patients with RA and in the control group to determine the genotype most characteristic of this disease. Materials and Methods: This case-control study was conducted in a group of 136 children with RA aged 14 to 18 years. In the control group, there were 143 practically healthy children of similar age without RA and orthopedic pathology. Both groups were tested for polymorphism IL-6 -174G/C using real-time Polymerase Chain Reaction (real-time PCR). The results were statistically processed using the Pearson's Chi-square test. Results: The distribution of -174G/C genotypes in the IL-6 gene is significantly different in patients with RA when compared with the control group. In patients with RA, heterozygous carriers of -174G/C (52.94%) prevail, while in the control group the most numerous group are homozygous carriers of -174G/G (40.56%). Conclusion: As a result of this study, it was possible to identify significant differences in the distribution of the genotypes -174 G/C polymorphism in the IL-6 gene between patients with RA and subjects of the control group. In relation to the European population of the Russian Federation, this polymorphism can serve as a diagnostic marker in the study of the pathogenesis of RA.