Crohn's disease involves a Th-1-mediated inflammatory response which has upregulated IFN-γ, TNF-α, IL-12 and IL-18, and act as pro-inflammatory cytokines and downregulated IL-5,IL-18 and IL-21, which act as an anti-inflammatory cytokines whereas ulcerative colitis which is Th-2 mediated, all Th-2 mediated cytokines like IL-5IL-6,IL-13, IL-17 and TNF-α are upregulated and act as pro-inflammatory cytokines, whereas IL-18 is downregulated and act as an anti-inflammatory cytokine [5]. This evidence concerns the gene IL18 and Crohn disease.