Crohn's disease is a chronic illness in which the intestine
(bowel) becomes inflamed and ulcerated (marked with sores). Along with
ulcerative colitis, Crohn’s disease is part of a group of diseases known as
inflammatory bowel disease (IBD).
Crohn’s disease most commonly affects the lower part of the
small intestine (ileum), although it can occur in any part of the large or small
intestine, stomach, esophagus or even the mouth. It can occur at any age, but it
is most common between the ages of 15 and 30.
Crohn's disease can disrupt the normal function of the bowel in a number of ways. The tissue may:
- Swell, thicken, or form scar tissue leading to blockage of the passageway inside the bowel
- Develop ulcers that can involve the deep layers of the bowel wall
- Lose its ability to absorb nutrients from digested foods (malabsorption)
- Develop abnormal passageways (fistulas) from one part of the bowel to
another part of the bowel, or from the bowel to nearby tissues such as the bladder or vagina.
Symptoms of Crohn’s disease
People with Crohn's disease experience periods of severe
symptoms followed by periods of remission that can last for weeks or years.
Unfortunately there is no way to determine when a remission will occur or when
symptoms will return. The symptoms of Crohn's disease depend on where the
disease occurs in the bowel and its severity. In general, symptoms at times
include:
- Chronic diarrhea
- Rectal bleeding
- Weight loss
- Fever
- Abdominal pain and tenderness (often on the right side of the lower
abdomen)
- Feeling of a mass or fullness in the lower, right abdomen
- Delayed development and stunted growth (in children)
Other symptoms can develop, depending on complications related
to the disease. For example, a person with a fistula (abnormal passageway) in
the rectal area may have pain and discharge around the rectum. Other
complications from Crohn’s disease include:
- Arthritis
- Kidney stones
- Gallstones
- Inflammation of the eyes and mouth
- Skin rashes or ulcers
- Liver disease
Causes of Crohn’s disease
The cause of Crohn's disease is unknown. It is likely that
Crohn's disease is at least partially an inherited disease that causes an
abnormal response of the immune system in the gastrointestinal tract. Recently,
the first gene associated with Crohn’s disease was identified. This gene is
called the NOD2 or CARD15 gene. Abnormalities in the gene are found in up to 20%
of patients with Crohn’s disease. People who have a relative with Crohn’s
disease are 10 times more likely to develop the disease themselves. If the
affected relative is a sibling, the risk jumps to 30 times more likely to
develop Crohn’s disease. Jewish people of European descent also have a greater
risk for developing the disease.