Irritable Bowel Syndrome's Possible Genetic Link Studied

Irritable bowel syndrome is a common problem affecting about one in 10 adults. However, many people don’t talk about irritable bowel syndrome, which causes abdominal cramping, constipation and diarrhea. The study, which is published in the December issue of Gut, an international journal in gastroenterology, shows that the risk of having irritable bowel syndrome is nearly double in the families of people with the disorder.

“The next challenge is determining nature versus nurture,” said G. Richard Locke, M.D., a Mayo Clinic gastroenterologist and one of the authors of the study. “Is this due to a gene or genes or is it due to a shared environmental factor? Our group is active in investigating these issues.”

In developing the study, researchers noted that people with irritable bowel syndrome often report family members with similar symptoms. The researchers hypothesized that if there is a familial connection, there would be an increased frequency of irritable bowel syndrome in direct relatives of irritable bowel syndrome patients compared to relatives of people without irritable bowel syndrome.

Others who conducted the study include Jamshid Kalantar, M.D., Alan Zinsmeister, Ph.D., Christopher Beighley, and Nicholas Talley, M.D., Ph.D. Dr. Kalantar was a research fellow at Mayo Clinic during the study, but is now with the Department of Medicine, University of Sydney, Australia. Mr. Beighley now works in West Virginia. The others are with Mayo Clinic in Rochester.

In the study, patients with irritable bowel syndrome seen at Mayo Clinic and their spouses filled out a bowel disease questionnaire and provided the names and addresses of their directrelatives. Researchers then sent a bowel disease questionnaire to 355 relatives of the patients and their spouses, and 71 percent responded. Irritable bowel syndrome occurred in 17 percent of the patients’ relatives compared with 7 percent in spouses’ relatives.