Patients manifested chronic non‐bloody watery diarrhea (MC‐like symptoms) with normal endoscopic appearance (n = 7; Fig. 1) or occult (n = 9)/gross (n = 10) hematochezia, abdominal pain (n = 2) or mucin secretion (n = 2) (IBD‐like symptoms) endoscopically showing mucosal reddening with or without focal erosion/aphtha (n = 26; Fig. 2). The gene discussed is MUC5AC; the disease is inflammatory bowel disease.