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 different diseases like diabetes, sarcoidosis and asthma has been reported. The aim of the present 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 Korean population. Methods: We examined two SNPs of IL-18 in 70 patients with AOSD and 204 healthy control individuals. The genotyping were performed using sequence specific PCR. Haplotypes were analyzed by the estimated haplotype program. The patients with AOSD were subdivided intogroups according to disease course: monocyclic systemic, polycyclic systemic, and chronic articular type. Results: As for the ⁣607 genotypes, 13 of the 69 patients had CC genotype (18.8%), 36 the CA type (52.2%) and 20 the AA type (29.0%). AOSD patients had higher frequency of A allele at ⁣607 when compared to controls (OR 1.48, 95% CI 1.00∼2.18, p=0.048). AOSD patients had significantly higher frequency of AA genotypes at ⁣607 when compared to controls (AA vs CA& CC, OR 1.90, 95% CI 1.01∼3.58, p=0.044). As for the ⁣137 genotypes, of the 68 patients, 57 had GG genotype (83.8%), 9 the GC type (13.2%) and 2 (2.9%) had the CC type. No differences were found in allele and genotype frequencies between two groups. The haplotype frequencies of the IL-18 polymorphism were not significantly different between patients with AOSD and controls. The frequency of ⁣137 GG genotype was significantly increased in chronic articular type compared to healthy control and systemic type of AOSD. Conclusion: In IL-18 gene polymorphisms, the A allele and AA genotye at position ⁣607 might be genetic risk factors for the development of AOSD in Korean population. Further investigation in larger groups is required to provide more conclusive evidence regarding the role of the IL-18 gene polymorphism in AOSD.

Keywords: Adult onset Still's disease, Interleukin-18, Polymorphism