The IL-18 gene is located on chromosome 11q22. Two functional gene polymorphisms -607A/C and -137G/C are found in its promoter region [9]. Giedraitis et al. analyzed IL-18 gene promoter sequence and found a change from C allele to A allele at position -607 and a change from G to C at position -137 of the IL-18 promoter region [9]. They estimated transcription activity of IL-18 gene promoter fragments and found that C allele of -607A/C or G allele of -137G/C showed higher activity of IL-18. The participants with CC homozygote of -607A/C or GG homozygote of -137G/C polymorphism exhibited somewhat higher levels of IL-18 mRNA compared with other genotypes