Association of Single Nucleotide Polymorphisms in the IL27 Gene with Rheumatoid Arthritis

Rheumatoid arthritis (RA) is one of the autoimmune diseases, where different polymorphisms in cytokine genes play a pathogenic role. Interleukin 27 (IL-27) is a novel pro-/anti-inflammatory cytokine, an excellent candidate for chronic inflammatory disease studies. The aim of the study was to identify polymorphisms in the IL-27 gene and their possible association with susceptibility to and severity of RA. Two hundred and seventy-four patients with RA and of 295 healthy individuals were examined for -924A/G and 4730T/C IL27 gene polymorphisms using PCR-RFLP method and TaqMan SNP genotyping assay, respectively. Haplotype frequencies of IL-27 polymorphisms were estimated using SHEsis platform. Frequencies of the -924GG genotype and the -924G allele were statistically higher in RA patients comparing with the healthy control group (P=0.008 and P=0.004, respectively). Overall, strong LD was observed between the IL27 gene -924A/G and 4730 T/C polymorphisms (D=0.613, r2=0.199). From four possible haplotypes, frequencies of two (CA and CG) showed significant differences between both examined groups (respectively: P<0.001 and P=0.001062). The genotype-phenotype analysis showed significant association between the IL-27 4730 T/C polymorphism and HAQ score and means value of the ESR, additionally they revealed that individuals with the polymorphic allele -924G had more advanced disease than wild-type allele carriers. Present findings indicated that IL27 -924A/G polymorphism may be involved in susceptibility to RA in the Polish population.