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