FGFR4 and irritable bowel syndrome: With the presumption that bile acid malabsorption of moderate severity might play a role in IBS-D, Wong et al. [114] tested 435 IBS subjects and 270 healthy controls and found out that a functional KLB gene variant is involved in the modulation of protein stability associated with colonic transit in IBS-D, association mediated by two genetic variants in FGFR4 (FGF19-FGFR4-KLB pathway).