A keyword search for “IBS,” “serotonin receptor 7,” “IBS AND serotonin receptor 7,” “5-HT7,” "bowel sensitivity," and "visceral hypersensitivity" was made, and then the results were meshed with “biosynthesis,” “adverse effects,” “immunology,” and “therapeutic use.” Specifically, studies to be included were regarding visceral hyperalgesia and bowel sensitivity related to IBS, serotonin pathways, and their relation to IBS, as well as research on serotonin type 7 and its relation to bowel function. This evidence concerns the gene HTR7 and irritable bowel syndrome.