The cause of the inflammatory bowel diseases (IBD) ulcerative colitis and Crohn’s disease is not yet known.
However, there is good evidence to suggest that these diseases are due to a combination of factors, including genetic predisposition, environmental factors, and alterations in the function of the immune system.
There is strong evidence to suggest a genetic basis for IBD, including familial clustering and racial and ethnic differences in risk for IBD.
A large percentage of affected individuals will have family history of IBD, with the highest risk among first-degree relatives (Son Daughter). At this time, a positive family history is the single-greatest risk factor for Bowel Disease, with relatives of affected individuals having at least a 10-fold increased risk. (know your family history)
Increased rates of IBD among identical twins compared to fraternal twins, and among siblings compared to spouses of affected individuals, suggests that genetic rather than environmental factors are primarily responsible for the observed familial aggregation or concentration of incidence for the disease.
Racial differences in Bowel Disease incidence exist, with the highest rates among Caucasians. Also, there is evidence for ethnic aggregation of IBD, with higher rates of IBD among those of Jewish descent. Furthermore, within Jewish populations, rates are higher in Ashkenazi than Sephardic Jews. These differences occur across different time periods and geographic areas, suggesting a genetic basis as the most likely explanation for these findings.
Recently, the first gene associated with Crohn’s disease, the NOD2 gene, was identified. There is intense ongoing research into understanding how defects in the NOD2 gene leads to Crohn’s disease and into finding the other genes that cause IBD (It is likely that there are 4-5 genes involved).
How common bowel cancer is in the UK
Bowel (colorectal) disease is the 4th most common cancer in the UK after breast, lung and prostate cancer. In the UK around 41,600 people are diagnosed with bowel cancer each year.
A strong family history usually means you have relatives diagnosed with bowel cancer, especially if they are in different generations of your family. It can also mean you have one or more relatives diagnosed at a particularly young age. Examples of a strong family history are
- 1 first degree relative diagnosed before the age of 45.
- 2 first degree relatives diagnosed at any age.
- The same Gender.
A first degree relative is a parent, brother or sister, son or daughter. To have a strong family history, the affected relatives must all come from the same side of your family.
If you think you could have a family history of bowel cancer, see your GP with the facts and conditions of other members. If your doctor agrees, they will probably refer you to a specialist genetics service. They will look into your background closely by talking through your family history and asking detailed questions about your family’s health and illnesses.
You may have blood tests as part of this investigation other signs could be rapid weight Loss/Gain etc.
If the geneticist agrees that you do have a higher than average risk of bowel cancer, you’ll then see a bowel specialist. The bowel specialist will talk to you about having regular tests (screening) to pick up any signs of cancer as early as possible.