Tenapanor hydrochloride (hereafter referred to as ‘tenapanor’) is a first-in-class, minimally absorbed, small-molecule inhibitor of gastrointestinal sodium/hydrogen (Na+/H+) exchanger isoform 3 (NHE3, SCL9A3) for the treatment of irritable bowel syndrome with predominant constipation (IBS-C) in adults [9]. The gene discussed is SLC9A3; the disease is irritable bowel syndrome.