Crohn's disease is a chronic inflammatory disease of the intestines, which can affect any area of the gastrointestinal tract. Areas of healthy bowel tissue can be found between sections of diseased intestinal tissue. The ileum, which is the lowest portion of the small intestine, is the most commonly affected area. The inflammation extends deep within the intestinal lining causing abdominal pain and chronic diarrhea. The exact cause of this disease has evaded scientists and medical experts since it was first identified over 75 years ago. Research indicates an abnormality in the body's immune system, genetics, and environmental factors as possible causes of Crohn's disease.
A long held theory is that the immune system of individuals with Crohn's disease reacts abnormally. According to the National Institute of Diabetes and Digestive and Kidney Diseases website, the immune system of a Crohn's disease patient mistakes bacteria, foods, chemicals, and pollens as being foreign. In response, the immune system attacks the antigens by producing white blood cells which accumulate in the lining of the intestines. Chronic inflammation results and leads to ulceration and bowel injury (1). Scientists have found that high levels of tumor necrosis factor (TNF) are present in patients with this disease. TNF is a protein produced by the immune system.
About 20 percent of Crohn's disease patients have a blood relative with some form of inflammatory bowel disease. Most often the link is between siblings and sometimes between a parent and an offspring. People of Jewish heritage have a higher risk of developing Crohn's disease and Afro-Americans have a decreased risk of developing this disease (1).
In April 2007, an international team of researchers identified several new genetic risk factors for Crohn's disease. This discovery offered promise for an improved understanding of the true causes of this disease and identification of new casual pathways that can be targeted. Scientists identified ATG16L1, a gene which is believed to be involved in the process of inflammation. Ramnik Xavier, M.D., and Mark Daly, PhD., of Harvard Medical School, proposed that a variation in the ATG16L1 gene may alter its normal function leading to inappropriate immune responses and an increase risk for developing the disease. Two other genes, PHOX2B and NCF4, were identified and are thought to have a role in the immune system's response to bacteria (2).
Environmental risk factors for developing Crohn's disease, as reported by the Mayo Clinic, are cigarette smoking and living in cities and industrial nations. The use of isotretinoin, which is a medication prescribed to treat cycstic acne or acne resistant to other treatments, has been reported in some cases of Crohn's disease (3).
(1) www.niddk.nih.gov
(2) www.sciencedaily.com
(3) www.mayoclinic.com
Maryann Gromisch is a registered nurse with clinical experience in medical, surgical, and critical care nursing. She has experience assisting a gastroenterologist in a private practice setting.