ABCG2 and constipation disorder: Functional genes associated with transporters, ABC transporters, the secretion system, transcription factors, the phosphotransferase system, the two component system, and bacterial motility proteins were significantly upregulated in the gut microbiome of children with diarrhea (Supplementary Figure S2C), whereas ribosome-related genes were enriched in the gut microbiome of children with constipation.