introduction
Crohn’s disease (CD) is a chronic inflammatory disease in which the body’s immune system overreacts, causing inflammation of the intestine. Along with Ulcerative colitis (UC), these diseases are referred to as Inflammatory bowel disease (IBD). In rare cases, patients have been diagnosed with both CD and UC, a condition called Crohn’s Colitis.While the exact chain of events that lead to CD is unknown, it is believed to be an autoimmune disease. The abnormal immune response and inflammation of the intestine lead to bloody diarrhea, abdominal pain, and weight loss. The symptoms of CD vary in severity and onset, they may start gradually or suddenly.
Crohn’s disease can affect any part of the gastrointestinal tract but most commonly it affects the end of the small intestine (the ileum) and the beginning of the large intestine (the colon). All layers of the intestine may be involved and between patches of diseased bowel there can be normal healthy bowel.
Crohn’s disease can associate with other health issues, such as liver problems, arthritis, and skin and eye problems. The risk of developing CD in one’s lifetime is 0.5% with an estimate of 400,000 to 600,000 people in North America developing CD each year. Crohn’s disease is most commonly observed in Europe and North America and the number of cases has increased over the last several decades.
Genetic factors are known to play a significant role in the development of CD. To date 11 genetic variants have been found that increase the risk of developing CD. These variants are located in or near the NOD2 gene on chromosome 16, in the IL23R gene on chromosome 1, in the ATG16L1 gene on chromosome 2, in the IRGM gene on chromosome 5, in the NKX2-3 gene on chromosome 10, in the PTPN2 gene on chromosome 18, in the BSN gene on chromosome 3, in the NELL1 gene on chromosome 11, in the IBD5 region on chromosome 5, and in the chromosomal regions 10q21 and 5p1.
The deCODEme Genetic Scan identifies the 11 variants listed above in customers of Northern European descent and provides interpretation on their associated risk for developing CD. Currently no data are available for people of other ethnicities for the variants listed above.
risk factors
The true causes of Crohn’s disease (CD) are unknown, but it seems that the immune system may be provoked by many factors, including respiratory infections or physical stress. Known risk factors for CD include:- Age: The prevalence of the disease is highest during the second and third decades of life, but CD can occur in people over 70 years and in childhood, although it is not common in children younger than 15 years.
- Ethnicity: Individuals of European decent are at greater risk of developing CD than other ethnic/racial groups.
- Smoking: Smoking adds to the risk for CD. Former smokers are also at greater risk than nonsmokers.
- Genetic Factors: Several genetic factors increase the risk for developing CD and having a family member with CD increases the risk of developing the disease. If a person has a relative with the disease, his or her risk is about 10 times greater than that of the general population. If the relative is a brother or sister, the risk is 30 times greater.
more information
You can find out more information about CD by talking with your doctor and visiting these Web sites:The Crohn’s and Colitis Foundation of America
MedlinePlus Article on Crohn’s Disease
Inflammatory Bowel Disease: Crohn’s Disease and Ulcerative Colitis
Inflammatory Bowel Disease - Patients - American College of Gastroenterology