Allo-HCT patients with GVHD developed microbial disruption preonset GVHD. (A-C) Volcano plot [−log₁₀(FDR P value) vs log₂(fold change)] representation of microbial dysbiosis of preonset GVHD (day −20 to −1 relative to onset) and no-GVHD (day −3 to +102 relative to allo-HCT) fecal samples. Plot includes taxa with mean relative abundance within samples >0.1% and highlights the 20 genera with strongest FDR corrected P-value significance (≤0.05). No-GVHD patients had higher abundance of commensals belonging to the class Clostridia when compared with non-GI, UGI, and LGI cohort. p, phylum; o, order; f, family; g, genus; Proteo, Proteobacteria.