Furthermore, high circulating levels of IL-18 have been measured in a large number of inflammatory diseases [21,29,30,31,32,33,34], and IL-18 has been shown to be overexpressed in affected organs, such as the intestinal mucosa in Crohn’s disease, the synovial tissue in rheumatoid arthritis, and the skin lesions in psoriasis [35,36,37]. This evidence concerns the gene IL18 and Crohn disease.