RESUMO
OBJECTIVE: The interleukin-18 (IL-18) encoding gene has three common single-nucleotide polymorphisms at -607C/A, -137G/C and +105A/C, which have been reported to be associated with several diseases. The aim of this study is to test whether IL-18 polymorphisms could act as genetic markers for renal stone disease. MATERIAL AND METHODS: A control group of 104 healthy subjects, and 272 patients with recurrent calcium oxalate stones were examined. Polymerase chain reaction-based restriction endonuclease analysis was used to detect IL-18 polymorphisms. RESULTS: The patient and control groups differed significantly in genotypic expression of the IL-18 +105A/C polymorphism. The prevalence of the A/C + C/C genotypes in the patients was higher than that in the controls. The allelic frequency of IL-18 +105A/C differed significantly between the patients and the controls. The odds ratio (OR) of the A/C heterozygote of IL-18 +105A/C associated with urolithiasis was 2.772. The OR of the A/C + C/C genotypes of IL-18 +105A/C associated with urolithiasis was 3.097. The OR per copy of the C allele of IL-18 +105A/C associated with urolithiasis was 4.143. There were also significant differences in the prevalence of genotype IL-18 -137G/C polymorphisms between the patients and controls. The distribution of the G/G homozygote in the patients was higher than that in the controls. There was no significant difference in genotype and allelic frequency at the IL-18 -607C/A polymorphism between patients and control subjects. CONCLUSION: The results indicate that IL-18 +105A/C polymorphisms may play a role in the development of urolithiasis.