AimInterleukin 23 (IL-23) and its receptor (IL-23R) seem to play a major role in differentiation of CD4(+) T cells into Th17 cells, induction of IL-17 production, and activation of inflammatory pathways. Recent studies have suggested the association of IL-23R polymorphisms with bone and articular inflammation in diseases such as ankylosing spondylitis and rheumatoid arthritis. The aim of this study was to determine the association between IL-23R polymorphisms and juvenile idiopathic arthritis (JIA). MethodA case-control study on 55 patients with JIA and 78 healthy controls was performed. All samples were genotyped for eight single nucleotide polymorphisms (SNPs) of IL23R (rs1004819, rs2201841, rs10889677, rs1495965, rs7517847, rs10489629, rs11209026 and rs1343151), using real-time polymerase chain reaction Taqman genotyping technique. Forty-two patients and 42 healthy controls were chosen randomly to measure the level of serum IL-17A using enzyme-linked immunosorbent assay. ResultsAlthough the heterozygous genotype of rs1004819 (GA) showed a weak, but statistically significant protective effect on polyarticular subtype (P=0.03), none of the selected SNPs were associated with JIA overall. Indeed the analysis of haplotypes did not show any significant association with JIA. Serum IL-17A level was not significantly different among patients and healthy controls and between JIA subtypes, as well. Moreover, there was no significant correlation between SNPs and serum IL-17A concentration. ConclusionThis is the first study of the IL-23R gene in Iranian patients with JIA. Our results did not show any strong association between IL-23R polymorphisms and JIA disease or serum IL-17A levels. The only association was seen between rs1004819 and polyarticular JIA. Further larger studies may help clarify the role, if any, of the IL-23/IL-17 pathway in the pathogenesis of JIA.