Association of Interleukin-18 Polymorphism with Adult Onset Still’S Disease in Korea

Abstract

Objective: It has been suggested that overproduction of interleukin -18 (IL-18) may contribute to the pathogenesis of adult onset Still’s disease (AOSD) . Recently, positive association between a polymorphism in the IL-18 gene and various diseases like diabetes, sarcoidosis and asthma has been reported .The aim of this study was to investigate the potential association of two single-nucleotide polymorphisms (SNPs) at position -137 (G/C) and -607 (C/A) in the promoter region of the IL-18 gene with susceptibility and clinical feature of AOSD in the Korea. Methods: IL-18 SNPs were assessed in 60 patients with AOSD and 122 healthy controls. The genotyping were performed by PCR-RFLP method. Haplotypes were calculated by the EHl program. The patients with AOSD were subdivided into groups according to disease course : monocyclic systemic, polycyclic systemic,and chronic destructive type, and according to extent of arthritis : nonarticular, oligoarticular or polyarticular types. Result: Gene frequency at -137 promotor region in AOSD patients(N=58) was GG 48 (82.8 %) , GC 10(17.2%) and no CC, whereas 87(71.3%), 35(28.7%), 0(0%) respectively in normal controls. AOSD patients had higher frequency of GG genotypes and the G allele at -137 compared to controls(OR =1.93 , 95 % CI 0.88-4.24, p=0.0379 and OR=1.78 , 95% CI 0.85-3.72, p =0.0431). However, no significant difference was observed in the distribution of either alleic or genotypic frequencies at position -607. The haplotypes frequencies of the IL-18 polymorphism were similar between patients with AOSD and controls. There was no association between the genotypes and disease course or extent of arthritis in AOSD.Conclusion: In conclusion, the GG genotype and G allele at position -137 of IL-18 promotor region might be potential genetic risk factor for AOSD in Korean population. Further investigations in larger group or meta-analysis are required to provide more strong evidence in association between IL-18 SNPs and AOSD.