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

W.C. Jang^1*, S.B. Park^1*, Y.H. Nam¹, S.S. Lee⁵, J.W. Kim², I.S. Chang³, K.T. Kim³, H.K. Chang⁴

¹Department of Chemistry, ²Department of Laboratory Medicine, ³Department of Emergency Medicine and ⁴Department of Internal Medicine, Dankook University, Cheonan; ⁵Department of Internal Medicine, Chonnam National University Medical School, Chonnam, South Korea.

ABSTRACTWon-Cheoul Jang, PhD; Sang-Bum Park, MS; Youn-Hyoung Nam, MS; Shin-Seok Lee, MD; Jong Wan Kim, MD; In Seong Chang, MD; Kab Teug Kim MD; Hyun Kyu Chang, MD.
*These two authors contributed equally to this manuscript.
This study was supported by grants from the Institute of Life Science, Dankook
University Medical Center, in 2004.
Please address correspondence to:
Hyun Kyu Chang, MD, PhD, Division of Rheumatology, Department of Internal Medicine, College of Medicine, Dankook University, 16-5 Anseo-Dong, Cheonan, Chungcheong Nam Do, 330-715, South Korea.
E-mail: hanks22@naver.com
Received on October 18, 2004; accepted
in revised form on June 14, 2005.
Clin Exp Rheumatol 2005; 23 (Suppl. 38): S59-S63.
© Copyright Clinical and Experimental Rheumatology 2005.

Key words: Behçet’s disease,
interleukin-18, polymorphism.

Objective
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.

Methods
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 c2 test, together with Yate’s correction where appropriate. Haplotype analysis was assessed using the EH program.

Results
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).

Conclusion
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.

Key words
Behçet’s disease, interleukin-18, polymorphism.

*These two authors contributed equally to this manuscript.
This study was supported by grants from the Institute of Life Science, Dankook University Medical Center, in 2004.
Please address correspondence to: Hyun Kyu Chang, MD, PhD, Division of Rheumatology, Department of Internal Medicine, College of Medicine, Dankook University, 16-5 Anseo-Dong, Cheonan, Chungcheong Nam Do, 330-715, South Korea.
E-mail: hanks22@naver.com

Clin Exp Rheumatol 2005; 23 (suppl. 38): S59-S63.
© CLINICAL AND EXPERIMENTAL RHEUMATOLOGY 2005.