“IBS is characterized by persistent or intermittent episodes of abdominal pain, bloating, and abnormalities in bowel habits and stool form, without morphological or biochemical abnormalities.” Linaclotide (Linzess®) is a guanylate cyclase-C (GC-C) agonist, which is a 14-amino acid polypeptide.476,477 Linzess® was approved by the FDA in December 2012 for the treatment of adult patients with constipation-predominant irritable bowel syndrome (IBS-C) and chronic idiopathic constipation (CIC). The gene discussed is NPR3; the disease is irritable bowel syndrome.