Relative to HF, HF+XY increased xylose isomerase, butyrate-acetoacetate CoA-transferase, xylulose kinase, L-lactate dehydrogenase, succinyl-CoA:acetate CoA-transferase, propionate kinase, and endo-1,4-beta-xylanase predicted gene counts in the colonic mucosa (Q < 0.05). The gene discussed is XYLB; the disease is hydrops fetalis.