Question

Analyze why genetic or immune factors, rather than infectious agents, are hypothesized to be the cause of ulcerative colitis.

Answer 1

• Ulcerative colitis is a complex chronic inflammatory disease that affects the large intestine and the rectum.
• Immune Factor : The exact pathogenesis of ulcerative colitis is unknown. Patients with ulcerative colitis show abnormalities in the response of their immune system. It is unsure whether the immune response causes the disease or is in response to the disease. It is likely that no one pathogen or factor is the sole cause of Ulcerative colitis.
• The digestive tract becomes inflamed when your immune system tries to fight off the invading microorganism (pathogen). It's also possible that inflammation may stem from an autoimmune reaction in which your body mounts an immune response even though no pathogen is present. Therefore, ulcerative colitis can be defined as an autoimmune disease, a disease in which the immune system malfunctions, attacking some part of the body.

• Genetic factors : A genetic component to the aetiology 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,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 human leukocyte antigen associations which may be at work. In fact, this linkage on chromosome 6 may be the most convincing and consistent of the genetic candidates.

No infectious agent has been cultured or identified in anyone with ulcerative colitis. Therefore, it is increasingly unlikely that ulcerative colitis is caused by an infectious agent.It seems most likely that ulcerative colitis is caused by a genetic or immune factor.