The completion of the Human Genome Project in April 2003 gave researchers the ability to read nature's complete genetic blueprint for humans. This was a significant milestone in our understanding of the role genes play in various diseases.
We know that genes, along with environmental factors, increase an individual's risk for diseases such as Crohn's. The key to developing effective treatments is to determine which ones are responsible. This is no easy task. There are 22,000 genes that make up our genome (all of our genes together), which consist of three billion subunits of DNA.
Experts believe that some genes already identified with Crohn's disease are involved in the body's faulty defense against microbes in the digestive system, making the immune system to attack the lining of the digestive tract and causing inflammation. We have millions of microbes, which are tiny organisms, in our body that keep us healthy.
The genetic component of Crohn's disease tends to run in families. It is more common in certain ethnic groups, especially those of central and eastern European Jewish decent. If you have one parent who has Crohn's, your lifetime risk of developing some form of Inflammatory Bowel Disease is 10 percent, and seven to nine percent that you will get Crohn's. If both your parents have Crohn's disease, your lifetime risk increases to 35 percent.
Scientists have already linked 32 genetic variations to Crohn's disease. This highlights the complexity of the disease and only explains about one-fifth of genetic risk. There may be hundreds more genes implicated, each of which increases a person's susceptibility to the disease by a small amount.
In a 2008 study in the journal Nature Genetics, researchers identified three genes implicated in Crohn's that were shown to also influence the risk for type 1 diabetes and asthma, suggesting the possibility of a common genetic mechanism.
One of these genes, called CCR6, is part of the signaling mechanism that causes the white blood cells in the gut to become overactive, leading to inflammation. CCR6 is also present in people who have inflamed joints. Knowing which genes are involved helps researchers develop new treatments.
Another study reported in the June 2008 issue of Gastroenterology identified genetic markers that can also help discriminate between Ulcerative Colitis, Crohn's disease and Irritable Bowel Syndrome.
The results of these, and other, studies of genetic markers are exciting for researchers and patients with Crohn's. The results will facilitate quick and reliable diagnosis of the disease, and lead to improved tools for disease management. By identifying genes associated with Crohn's, researchers hope to find specific targets for new drugs.
