Study Links Gene to Gut Flora and Crohn's Disease

A research team consisting of scientists from two countries has completed a study showing a relationship between a gene and the makeup of gastrointestinal bacteria, a suspected culprit in the development of Crohn's disease.

The scientists represented the Karolinska Institutet in Sweden and Scotland's University of Glasgow. Their findings suggest that the human genome -- billions of particles organized into DNA molecules --

Study Links Gene to Gut Flora and Crohn's Disease
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might be at least partially responsible for which microbes reside in the digestive tract, according to Medical News Today. The collection of these microbes, also numbering in the billions, is known as the gut microbiota. Its composition varies among humans.

The hypothesis suggested by the small study is that an individual's genetic makeup customizes his or her microbiota. While much more research will be necessary to determine how specific microbiota profiles are created, the hypothesis has significant implications for treating diseases associated with bacterial composition of the gut. Among them are obesity & Crohn's disease.

Crohn's disease is one of the two main types of inflammatory bowel disease (IBD). The Mayo Clinic says that the inflammation it leaves behind spreads deep into the layers of the intestine, though the illness can strike anywhere in the digestive tract. This incurable disease causes abdominal pain, severe diarrhea, and a host of other symptoms, some of which are also common to its cousin, ulcerative colitis, the other primary type of IBD.

Around 700,000 Americans suffer from Crohn's disease, according to the Crohn's & Colitis Foundation of America. Despite decades of research, scientists have not identified a specific cause of the illness. However, most blame a combination of issues. The most likely are a faulty immune system that causes the body to attack normally benign substances like "good" bacteria, genetics, and environmental factors.

The European study included a statistical analysis on DNA involving 30 specific genes for 51 healthy subjects with no history of intestinal disorders. These genes had already been linked to elevated risk of developing Crohn's.

A variation in one, known as the IRGM gene, was connected to higher-than-normal amounts of a microbe called Prevotella. Genetics Home Reference indicates that this gene furnishes instructions to make a protein with a role in surrounding and destroying invaders like bacteria and viruses.

Several variations in or near this gene are associated with an elevated risk for Crohn's. The study suggested that the IRGM gene could influence the makeup of a person's microbiota so that it favors a bacteria like Prevotella over a close relative, Bacteroides.

For Crohn's patients like me, the study offers the possibility of treating the disease by restoring normal intestinal flora rather than turning to surgery or anti-inflammatory or immunosuppressant medications with significant side effects. Linking a specific gene to gut flora and Crohn's disease could be the beginning of highly individualized treatment for the disorder.

14 January 2013