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Ulcerative Colitis

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Medical Author:

Adam Schoenfeld, MD

Medical Author:

George Y. Wu, MD, PhD

Medical Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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What is Ulcerative Colitis?

Ulcerative colitis is a chronic inflammation of the large intestine (colon). The colon is the part of the digestive system where waste material is stored. The rectum is the end of the colon adjacent to the anus. In patients with ulcerative colitis, ulcers and inflammation of the inner lining of the colon lead to symptoms of abdominal pain, diarrhea, and rectal bleeding.

Ulcerative colitis is closely related to another condition of inflammation of the intestines called Crohn's disease. Together, they are frequently referred to as inflammatory bowel disease (IBD). Ulcerative colitis and Crohn's diseases are chronic conditions that can last years to decades. They affect approximately 500,000 to 2 million people In the United States. Men and women are affected equally. They most commonly begin during adolescence and early adulthood, but they also can begin during childhood and later in life.

It is found worldwide, but is most common in the United States, England, and northern Europe. It is especially common in people of Jewish descent. Ulcerative colitis is rarely seen in Eastern Europe, Asia, and South America, and is rare in the black population. For unknown reasons, an increased frequency of this condition has been recently observed in developing nations.

First degree relatives of people with ulcerative colitis have an increased lifetime risk of developing the disease, but the overall risk remains small.

What Causes Ulcerative Colitis?

The causes 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 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 systems 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.

In the last 1 to 2 years, 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.