Doctors don't clearly understand what causes Crohn's disease. However, one theory involves immune system response as either a cause or a result of the disease. It is thought that the immune system may mistake bacteria and foods as "invaders" to the body. The immune system then attacks these invaders, causing white blood cells to gather in the innermost lining of the intestines. This reaction can lead to swelling and intestinal mucosa damage. Other conditions associated with inflammation in the GI tract may include:

• autoimmunity
• genes
• unknown environmental triggers

Risk factors
Crohn's disease seems to run in some families. As many as 20 percent of people diagnosed with Crohn's disease have a relative diagnosed with inflammatory bowel disease or other autoimmune disease. Crohn's can occur in people of all age groups but is most often diagnosed in young female adults and is most common in people between the ages of 20 and 30. Both men and women can have Crohn's disease. Some of the risk factors that might contribute to the development of Crohn's disease include:

• Acne medication use - Isotretinoin (Accutane) use may be associated with the development of inflammatory bowel disease.
• Age - Most people are diagnosed with Crohn's between the ages of 20 and 30.
• Diet - Environmental factors, including a diet high in fat or refined foods, may play a role in the development of Crohn's.
• Ethnicity - If you're Jewish and of European descent, you're four to five times as likely as other people are, to have Crohn's disease. Although whites have the highest risk of the disease, it can affect any ethnic group.
• Family history. You're at higher risk if you have a close relative, such as a parent, sibling or child, with the disease.
• Location - Crohn's disease occurs more often among people living in cities and industrial nations.
• Smoking - Smokers are far more likely to develop Crohn's disease than non-smokers.

If left untreated, medical problems related to Crohns can become more serious. Do you know which signs and symptoms to look for? To learn more about how you can identify signs of Crohn's Disease, read on. The next section on Crohns Disease Symptoms reviews common signs and symptoms of Crohn Disease.