Interleukin-18 gene polymorphisms in Korean patients with Behçet's disease

There is strong evidence that Th1-type cytokines play an important role in the pathogenesis of Behçet's disease (BD). Interleukin (IL)-18 is a proinflammatory cytokine that mediates Th1-polarized immune responses, and elevated levels of IL-18 have been observed in the sera and bronchoalveolar lavage fluid of patients with active BD. Therefore, the aim of this study was to investigate the potential associations of two single nucleotide polymorphisms (SNPs) at positions -137 (G/C) and -607 (C/A) in the promoter region of the IL-18 gene with a susceptibility to BD in the Korean population. Ninety-eight patients with BD and 105 healthy controls were studied. All of the subjects were genotyped using sequence specific PCR. The genotypes and alleles between patients with BD and controls were compared using the chi2 test, together with Yate's correction where appropriate. Haplotype analysis was assessed using the EH program. The genotype and allele distributions of the two SNPs did not differ significantly between patients with BD and controls. The haplotype frequencies of the IL-18 promoter polymorphisms were also similar between patients with BD and controls. However, the frequency of the GG genotype at position -137 was significantly higher in BD patients with ocular lesions than in those without ocular lesions (p = 0.026, pc = 0.048, OR = 4.1). Although the IL-18 gene polymorphisms were not associated with a susceptibility to BD in the Korean population, the patients carrying the GG genotype at position -137 had a higher risk of developing the ocular lesions. Further studies in other populations are required to confirm these results.