Furthermore, SHIP-1−/− mice without overt macroscopic ileitis had low ileitis grades, normal muscularis thickness, and normal levels of intestinal collagen (fibrosis) whereas SHIP-1−/− mice with ileitis had high ileitis grades, a significantly thickened muscularis, and evident fibrosis (Fig. 1I and K). The gene discussed is INPP5D; the disease is Crohn ileitis.