IL-18 gene polymorphisms in aphthous stomatitis vs. Behcet's disease in a cohort of Egyptian patients.

OBJECTIVE: A clinical investigation of the potential correlation of two single-nucleotide polymorphisms at -137 (G/C) and -607 (C/A) in the promoter region of the IL-18 gene, with the susceptibility to aphthous stomatitis and Behcet's disease. PATIENT AND METHODS: This study included 80 aphthous stomatitis patients and 80 patients with Behcet's disease. Eighty healthy subjects were enrolled as a control group. IL-18 single-nucleotide polymorphisms at -607 and -137 regions were analyzed using polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS: The genotype and allele distributions of the two regions did not differ significantly between patients with aphthous stomatitis and controls. The genotype and allele distributions at -607 were significantly different between patients with Behcet's disease [CC (P = 0.044), C allele (P = 0.043), A allele (P = 0.043)], and controls. The frequency of the GG genotype at position -137 in patients with Behcet's disease was associated only with a higher rate of ocular manifestations (OR= 1.4, CI= 0.76-2.7, P = 0.031). CONCLUSION: IL-18 gene polymorphisms were not associated with any susceptibility to aphthous stomatitis, while a positive association was found with patients with Behcet's disease regarding -607 promoter site. Moreover, patients with Behcet's disease carrying the GG genotype at position -137 had a higher risk of developing ocular manifestations.