A volcano plot of differential mRNA expression in the right colon mucosal biopsies in patients with BAD compared with IBS-D without ABAM: genes with increased mRNA expression in BAD were CLDN2, SPINK4, SERPINB5, C4BPB, CCL25, CXCL5, IL1RN, REG4 and FABP6 and the gene with decreased mRNA expression in BAD was GALNT15. ABAM, abnormal bile acid metabolism; BAD, bile acid diarrhoea; IBS-D, irritable bowel syndrome with diarrhoea; log2FC, log2 fold change.