MUC5AC and Peutz-Jeghers syndrome: PJS patients were enriched in potentially harmful bacteria in their gut, such as pathogenic bacteria and mucin-degrading bacteria (Escherichia-Shigella, Klebsiella, Fusobacterium, Veillonella, and Akkermansia), but depleted of commensal bacteria, such as butyrate-producing bacteria and lactate-producing bacteria (Faecalibacterium, Subdoligranulum, and Lactobacillus), at the genus level.