However, while it is clear from these studies that the TPL2 polymorphism results in increased IL-1β secretion it is not clear that this establishes a connection between increased secretion of IL-1β and susceptibility to Crohn's disease since the increased secretion of IL-1β was accompanied by increased secretion of other pro-inflammatory cytokines that could also contribute to increased inflammation in the patients with the polymorphism. Here, IL1B is linked to Crohn disease.