Interleukin‐1β and interleukin‐1 receptor antagonist gene polymorphisms in Korean patients with adult‐onset Still's disease

Abstract

Objective. Interleukin‐1 (IL‐1) has been implicated in the pathogenesis of several rheumatic inflammatory diseases, including adult‐onset Still's disease (AOSD) and systemic‐onset juvenile idiopathic arthritis (SoJIA). Several clinical trials also suggest that anakinra, a human recombinant interleukin‐1 receptor antagonist (IL‐1Ra), is effective in patients with AOSD and SoJIA. We have therefore investigated whether IL‐1β and IL‐1Ra gene polymorphisms are associated with the development and clinical features of AOSD.

Methods. Genomic DNA was isolated from 83 AOSD patients and 144 healthy controls. Genotyping of the two IL‐1β gene (IL‐1B+3954 and IL‐1B–511) polymorphisms was performed using polymerase chain reaction restriction fragment length polymorphism (PCR‐RFLP). Genotyping of the IL‐1Ra gene (intron 2, VNTR) polymorphism was performed using PCR‐based analysis. To compare genotype and allele frequencies, the χ²‐test or Fisher's exact test was used. Haplotype frequencies and pairwise linkage disequilibrium were also estimated. A p‐value <0.05 was considered significant.

Results. There were no significant differences in the genotype and allele frequencies of the IL‐1β and IL‐1Ra gene polymorphisms. No differences were also found in the IL‐1 gene cluster haplotypes between both groups. IL‐1 gene cluster polymorphisms had no effect on the clinical course and joint involvement pattern. Nevertheless, the IL‐1B–511 and IL‐1RN (VNTR) polymorphic sites were in linkage disequilibrium.

Conclusion. These results suggest that IL‐1β and IL‐1Ra gene polymorphisms are not associated with the development and clinical features of AOSD in Korean patients.