UCLA researchers in the Department of Gastroenterology have developed a DNA methylation-based algorithm to diagnose irritable bowel syndrome and other GI conditions. Blood-based genome-wide DNA methylation profiles have been utilized to develop a reliable test to diagnose irritable bowel syndrome (IBS) versus inflammatory bowel disease (IBD), celiac disease and other gastrointestinal diseases that mimic IBS. These methods provide a means to rule out IBS and rule-in active IBD or celiac disease, as well as to rule-out active IBD and celiac disease, and to rule-in IBS.