Your genes may influence gut bacteria that cause inflammatory bowel disease

Gut microbiota is the name given today to the microbe population living in our intestine. Our gut microbiota contains tens of trillions of microorganisms, including at least 1000 different species of known bacteria with more than 3 million genes (150 times more than human genes). Microbiota can, in total, weigh up to 2 kg. One third of our gut microbiota is common to most people, while two thirds are specific to each one of us. Extensive researches have shown that the gut microbiota, often developed at a very young age, can have a big impact on person’s health all life.  Previous studies have shown links between human gut bacteria and increased risk of a wide variety of diseases including diabetes, autism, heart disease, and even some forms of cancer. A study published in the Genome Medicine reported that people’s genes may have an influence over some of the intestinal bacteria that cause Crohn’s disease and ulcerative colitis.

Crohn’s disease is a chronic disease that causes inflammation of the digestive or gastrointestinal tract. Although it can involve any area of the GI tract from the mouth to the anus, it most commonly affects the small intestine and colon. Ulcerative colitis is a chronic disease of the large intestine that causes inflammation and ulceration of the colon’s innermost lining. Collectively know as inflammatory bowel disease (IBD), these conditions affect millions of people today.

The study, carried out by the researchers from the University of Minnesota, Harvard, MIT, University of Toronto and University Medical Center Groningen, is one of the largest international studies of its kind. The researchers examined three independent cohorts of a total of 474 adults with IBD who live in Boston, Mass. (USA); Toronto, Ontario (Canada); and Groningen (Netherlands). Doctors and nurses in those locations collected samples of DNA from each human subject and the DNA of their intestinal bacteria over about a two-year period. The researchers looked at thousands of microbial species and human genes.

The results showed that the human subjects’ DNA was linked to the bacteria in their intestines. Patients with IBD had lower biodiversity of bacteria and more opportunistic bacteria. In addition, this study confirmed the long time speculation that use of antibiotics is associated with a greater imbalance in the bacterial community in the intestines.

Thanks for reading!

Dr. Connie Wan

Journal Reference:  Dan Knights, Mark S Silverberg, Rinse K Weersma, Dirk Gevers, Gerard Dijkstra, Hailiang Huang, Andrea D Tyler, Suzanne van Sommeren, Floris Imhann, Joanne M Stempak, Hu Huang, Pajau Vangay, Gabriel A Al-Ghalith, Caitlin Russell, Jenny Sauk, Jo Knight, Mark J Daly, Curtis Huttenhower, Ramnik J Xavier. Complex host genetics influence the microbiome in inflammatory bowel disease. Genome Medicine, 2014; 6 (12): 107 DOI: 10.1186/s13073-014-0107-1