Rheumatoid arthritis (RA) is a chronic inflammatory disease in which cytokines play an important role. The aim of the present study was to examine the interleukin-6 (IL-6) -174 promoter polymorphism in patients with RA and its association with disease susceptibility and activity.
The study included 98 patients with RA diagnosed according to the criteria of the American College of Rheumatology. Polymerase chain reaction (PCR) amplification was used for analysis of the polymorphism at position -174 in the promoter of the IL-6 gene.
The distribution of IL-6 genotypes in RA patients did not differ from that in control subjects. Nevertheless, in patients with a GG genotype the active form of RA was more frequently diagnosed compared with homozygous CC and GC patients. Moreover, in carriers of two G alleles the parameters of disease activity score (DAS28), erythrocyte sedimentation rate (ESR), number of swollen and tender joints] were significantly increased.
We suggest that the IL-6 promoter polymorphism may be a genetic risk factor for RA activity.