A hard blow for those affected, because chronic inflammatory bowel diseases are very difficult to cure. Surgery is sometimes the last possibility to escape the constantly recurring pain. To be able to develop improved drugs, it is first necessary to understand how inflammatory bowel diseases arise.

However, it is not easy to trace the causes of chronic inflammatory bowel diseases since they are not only triggered by different errors in the DNA. Environmental influences, e.g. our daily habits also play a significant role. Moreover, there are several disease-related genes – some of them still unknown that mutually influence each other.

Therefore, it was an important step forward when recently - within a period of only three years - researchers of the National Genome Research Network (NGFN) discovered the second gene that causes inflammations of the intestinal mucosa.

Professor Stefan Schreiber (University of Kiel): "Chronic inflammation of the bowel occurs in some families with especially high incidence. If someone in the family suffers from Crohn’s disease or ulcerative colitis, siblings are at high risk to come down with the disease as well. This is confirmed by statistical evidence. For example, the disease risk for siblings of patients with Crohn’s disease is up to 35 times higher than for the rest of the population."

Thus, there is obviously a genetic predisposition for chronic inflammatory bowel diseases. In order to trace the disease-related genes in the genetic material, Professor Schreiber and his team had to investigate the DNA of several hundred affected families in laborious detail.

The Kiel scientists were successful. They found two disease-related genes which can trigger chronic inflammation of the intestine. The scientific names of these two genes are DLG5 and CARD15.

Both genes carry the blueprints for proteins that maintain an impermeable barrier against bacteria in the intestinal mucosa.

Page 2: Why errors in the blueprints for DLG5 and CARD15 cause chronic inflammatory bowel diseases