Ulcerative Colitis (cont.)
Adam Schoenfeld, MD
George Y. Wu, MD, PhD
In this Article
What Causes Ulcerative Colitis?
The cause of ulcerative colitis is not known. To date, there has been no convincing evidence that it is caused by infection or is contagious.
Ulcerative colitis likely involves abnormal activation of the immune system in the intestines. The immune system is composed of immune cells and the proteins that these cells produce. These cells and proteins serve to defend the body against harmful bacteria, viruses, fungi, and other foreign invaders. Activation of the immune system causes inflammation within the tissues where the activation occurs. (Inflammation is, in fact, an important mechanism of defense used by the immune system.) Normally, the immune system is activated only when the body is exposed to harmful invaders. In patients with ulcerative colitis, however, the immune system is abnormally and chronically activated in the absence of any known invader. The continued abnormal activation of the immune system causes chronic inflammation and ulceration. The susceptibility to abnormal activation of the immune system is genetically inherited. First degree relatives (brothers, sisters, children, and parents) of patients with IBD are thus more likely to develop these diseases.
There have been multiple studies using genome wide association scans investigating genetic susceptibility in ulcerative colitis. These studies have found there to be approximately 30 genes that might increase susceptibility to ulcerative colitis including immunoglobulin receptor gene FCGR2A, 5p15, 2p16, ORMDL3, ECM1, as well as regions on chromosomes 1p36, 12q15, 7q22, 22q13, and IL23R. At this early point in the research, it is still unclear how these genetic associations will be applied to treating the disease, but they might have future implications for understanding pathogenesis and creating new treatments.
What are the Symptoms of Ulcerative Colitis?
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Common symptoms of ulcerative colitis include rectal bleeding, abdominal pain, and diarrhea, but there is a wide range of symptoms among patients with this disease. Variability of symptoms reflects differences in the extent of disease (the amount of the colon and rectum that are inflamed) and the intensity of inflammation. Generally, patients with inflammation confined to the rectum and a short segment of the colon adjacent to the rectum have milder symptoms and a better prognosis than patients with more widespread inflammation of the colon. The different types of ulcerative colitis are classified according to the location and the extent of inflammation:
While the intensity of colon inflammation in ulcerative colitis waxes and wanes over time, the location and the extent of disease in a patient generally stays constant. Therefore, when a patient with ulcerative proctitis develops a relapse of his or her disease, the inflammation usually is confined to the rectum. Nevertheless, a small number of patients (less than 10%) with ulcerative proctitis or proctosigmoiditis can later develop more extensive colitis. Thus, patients who initially only have ulcerative proctitis can later develop left-sided colitis or even pancolitis.
Medically Reviewed by a Doctor on 7/16/2014
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