Genetic Variants Influence Crohn's Disease Development

Good bacteria prevented from working effectively in some inflammatory bowel disease patients.

Findings from a multicenter study revealed that Crohn’s disease may be caused by genetic variants that prevent beneficial bacteria from carrying out their job in the gut, according to a study published in Science.

Bacteroides fragilis bacterium are one of billions of microscopic organisms found in the human gastrointestinal system.

“Bacteria historically have been regarded as an enemy of the body, but more recently we have been identifying bacterial types that seem to be beneficial to health, especially in the case of IBD,” said study co-author Dermot McGovern, MD, PhD, FRCP(LON).

Researchers used both mouse models and human specimens, with a primary focus on Crohn’s disease.

The results of the study found that variants in the ATG16L1 gene had a negative impact on Bacteroides fragilis bacterium and their beneficial effects. It was also found that the genetic variants may be responsible for the increased risk of developing Crohn’s disease.

This negative impact prevents bacteria from carrying out a key function involving the suppression of inflammation of the intestinal lining.

“This study is very important because it identifies a completely novel mechanism through which these genes may lead to an increased risk of developing Crohn's disease,” McGovern said.

Researchers said the findings give physicians who treat patients with Crohn’s disease both insight and a better understanding of this disease, while also applying basic discoveries to patients suffering from inflammatory bowel disease.

“Given the low percentage of IBD patients who respond to drugs directed at the immune system, these results could point the way to improving treatment by identifying patients who might best respond to manipulation of bacteria in their digestive tract,” said study co-author Stephan R. Targan, MD.