Although no obvious differences in the weight, histopathology of colons between WT and DRD5−/− mice were observed before DSS treatment (Fig. S2C, D), more severe colitis on day nine after DSS administration was observed in DRD5−/− mice than in WT controls, as characterized by significantly greater body weight loss, higher disease activity index (DAI) score, and shorter colons in DSS-treated DRD5−/− mice (Fig. 2A–C). The gene discussed is DRD5; the disease is colitis.