Importantly, Gpr15-KO mice showed significant body weight loss during disease progression (Figure 3C), lower survival rate (Figure 3D), more colon polyps (of size > 2mm) in the middle and distal colon (measured at week 10; Figures 4A, B; Supplementary Figures 6B, C), and shorter colon length (measured at week 10; Figure 4C) than Gpr15-Het mice. This evidence concerns the gene GPR15 and polyp of colon.