While the cause of ulcerative colitis is still unknown, several, possibly interrelated, causes have been suggested. Some think that the smallest illness could spark the disease.
Genetic factors
A genetic component to the etiology of ulcerative colitis can be hypothesized based on the following:
- Aggregation of ulcerative colitis in families.
- Identical twin concordance rate of 10% and dizygotic twin concordance rate of 3%
- Ethnic differences in incidence
- Genetic markers and linkages
There are 12 regions of the genome which may be linked to ulcerative colitis. This includes chromosomes 16, 12, 6, 14, 5, 19, 1, 16, and 3 in the order of their discovery. However, none of these loci has been consistently shown to be at fault, suggesting that the disorder arises from the combination of multiple genes. For example, chromosome band 1p36 is one such region thought to be linked to inflammatory bowel disease. Some of the putative regions encode transporter proteins such as OCTN1 and OCTN2. Other potential regions involve cell scaffolding proteins such as the MAGUK family. There are even HLA associations which may be at work. In fact, this linkage on chromosome 6 may be the most convincing and consistent of the genetic candidates.
- Diet: A diet low in fermentable dietary fiber may affect ulcerative colitis incidence.
- Breastfeeding: There have been conflicting reports of the protection of breastfeeding in the development of inflammatory bowel disease. One Italian study showed a potential protective effect.
- Several scientific studies have posted that Accutane is a possible trigger of Crohn's Disease and Ulcerative colitis in some individuals. Three cases in the United States have gone to trial thus far, with all three resulting in multi-million dollar judgements against the makers of isotretinoin. There are an additional 425 cases pending.
Autoimmune disease
Some sources list ulcerative colitis as an autoimmune disease, a disease in which the immune system malfunctions, attacking some part of the body. In contrast to Crohn's disease, which can affect areas of the gastrointestinal tract outside of the colon, ulcerative colitis usually involves the rectum and is confined to the colon, with occasional involvement of the ileum. This so-called "backwash ileitis" can occur in 10–20% of patients with pancolitis and is believed to be of little clinical significance. Ulcerative colitis can also be associated with comorbidities that produce symptoms in many areas of the body outside the digestive system. Surgical removal of the large intestine often cures the disease. It may be caused by occlusions in the capillaries of the subepithelial linings, degenerated fibers beneath the mucosa and infiltration of the lamina propria with plasma cells.
Further Reading
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