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The direct causes of ulcerative colitis are unknown.

People living in northern latitudes and in urban areas of industrialized countries, seem to be at a higher risk of developing ulcerative colitis.

Up to 20% of people diagnosed have a relative with ulcerative colitis or Crohn's disease.

Ulcerative colitis is an inflammatory condition of the colon

Ulcerative colitis belongs to a group of diseases known as inflammatory bowel diseases (IBD), or diseases that cause inflammation in the digestive tract. In ulcerative colitis, small ulcers develop in areas where inflammation has damaged or killed the cells lining the colon. These ulcers usually become infected, which along with the bleeding, causes the colon to empty frequently, resulting in cramping abdominal pain and diarrhea.

Ulcerative colitis affects the innermost lining of colon or rectum

Ulcerative colitis is related to another type of IBD called Crohn's disease. The two diseases differ mainly in the depth of the inflammation and location within the digestive tract. Whereas ulcerative colitis affects the colon mucosa, the innermost lining of the colon and rectum, Crohn's disease causes inflammation deeper within the intestinal wall and occurs in other parts of the digestive system, including the small intestine, mouth, esophagus, and stomach.

A chronic disease with symptoms that can come and go

Symptoms of ulcerative colitis and its complications, vary depending on the extent of inflammation in the rectum and colon. About half of those diagnosed with ulcerative colitis continue to have mild symptoms that come and go, whereas others may experience chronic debilitating symptoms leading to life-threatening complications. Even those with a severe form of the disease may have relatively symptom-free periods between flare-ups.

Mostly diagnosed in young people of European origin

Ulcerative colitis can occur in people of any age, but the disease is usually first diagnosed in people in their 30s. It is more frequently diagnosed in individuals of European origin and in those of Jewish descent and affects men and women equally.

Genetics are one of the few known risk factors

The direct causes of ulcerative colitis are unknown. Those diagnosed with the disease often also have disorders of the immune system, but it is not known whether they are a cause, a result, or simply a correlate of ulcerative colitis. Genetic factors are known to play a significant role in the development of the disease. Up to 20% of people diagnosed have a close relative with ulcerative colitis or Crohn's disease.

deCODEme can calculate your genetic risk of ulcerative colitis

Nine genetic variants, on chromosomes 1, 3, 6, 10, 12 and 18 have been associated with increased risk of developing ulcerative colitis. Of these, four variants, on chromosomes 1, 3, 10 and 18, have also been associated with increased risk of developing Crohn's disease.

The deCODEme Complete Scan identifies all nine variants and provides an interpretation of the associated risk of ulcerative colitis for individuals of European descent. At the current time, risk information for other ethnicities is not available for these variants.

Risk Factors

Although the direct causes of ulcerative colitis are not known, certain factors have been found to be associated with higher risk of developing this disease:

• Age. Ulcerative colitis can develop at any age, but is most often diagnosed in people in their 30s. However, some may not develop the disease until after 50 or 60 years of age.
• Ethnicity. Ulcerative colitis is most common among people of European descent. People of African descent have a lower incidence, as do individuals who originate from Asia and South America. Jewish people have been found to have the highest risk of developing ulcerative colitis.
• Family history is currently the most prominent risk factor. Genetics have been found to play a significant role in the development of the disease, with reports of up to 20% of people diagnosed with ulcerative colitis having a first-degree relative with ulcerative colitis or Crohn's disease.
• Environmental factors. People living in northern latitudes and in urban areas of industrialized countries, seem to be at a higher risk of developing ulcerative colitis. Other environmental factors, such as a diet high in fat or refined foods, may also play a role.
• Inflamed bile ducts due to a condition called primary sclerosing cholangitis, have been found to be associated with ulcerative colitis.
• Left-Handedness. Curiously, people who are left-handed are reported to have a higher risk for both ulcerative colitis and Crohn's disease.

Prevention and treatment

Since the causes of ulcerative colitis are unknown, not much is known about how to prevent the disease. However, some studies have found that women who breastfeed their children are at lower risk than those who do not, and that smokers have a lower than average rate of ulcerative colitis (while they have a higher than average rate of Crohn's disease). This association most certainly should not encourage people to smoke, but raises interesting questions about the possible role of nicotine in the inflammatory processes of these bowel diseases.

Treatment for ulcerative colitis depends on the severity of the disease. It usually includes medications to reduce the inflammation, fight infections, and control pain, along with changes in diet to maintain adequate nutrition and prevent or reduce diarrhea.

Surgery may become necessary if the disease does not respond to medications or if complications arise. Surgery may also be considered sooner than later to prevent the development of colorectal cancer, which has been found to be associated with a long history of active ulcerative colitis.

Complications of ulcerative colitis that require urgent surgery include perforation of the colon, increased bleeding, and a condition called toxic megacolon, in which the muscle wall of the colon dilates and bacteria and gases build up inside the colon.

The most common surgical procedure for ulcerative colitis is proctocolectomy (removal of the entire colon and rectum). Unlike Crohn's disease, which can recur after surgery, ulcerative colitis is “cured” once the colon is removed.

More Information

• Crohn’s and Colitis Foundation of America
• KidsHealth on Inflammatory Bowel Disease in Children
• National Digestive Diseases Information Clearinghouse

This content was last reviewed on February 09, 2010.

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