GVHD patients present distinct preonset predicted PICRUSt pathways. (A) Radar chart representation of PICRUSt predicted functional pathway relative abundance from patients without GVHD and GVHD patients at preonset. Relevant pathways belonged to 6 main metabolic categories: carbohydrate degradation, nucleotide biosynthesis, amino acid biosynthesis, antibiotic resistance, vitamin K2 biosynthesis, and fermentation. Axis represents fold change relative to no-GVHD patients. (B) Heat map with hierarchical clustering of statistically significant (FDR P ≤ .05) unique PICRUSt pathways. Figure displays pathways found in a minimum of 5% samples within all groups. UGI and LGI GVHD patients show increased pathways associated with general antibiotic resistance, vitamin K2 metabolism, and nucleotide biosynthesis, with reduced representation related to amino acid biosynthesis compared with no-GVHD patients. There was reduced presence of butyrate-producing specific pathways in LGI patients (bold). ∗FDR P ≤ .05; ∗∗FDR P ≤ .01; ∗∗∗FDR P ≤ .001. NS, not significant.