How Likely Family Members Are to Have IBD: From UpToDate"First-degree relatives of patients with IBD are approximately 3 to 20 times more likely to develop the disease than the background population. A family history of CD is also associated with an earlier age of diagnosis in affected patients. However, the substantial majority of patients (>85 percent) have no family history of IBD."
Will Someone In Your Family Develop IBD?First-degree relatives (which includes parents, children, and full siblings) of people with IBD are more likely to have IBD than are people from the general population who do not have a first-degree relative who has IBD. The likelihood ranges from 3 to 20 times -- which is a very broad range.
In addition, Crohn's disease tends to be diagnosed at younger ages in people who have relatives with IBD. Yet, even though IBD is clearly passed through families, most people who have IBD do not have a relative who also has the disease.
In recent years, there have been several studies that seek to pinpoint the genes that carry the trigger for IBD. As many as nine genes have been identified as playing a role in developing IBD, however there may be several more that haven't been isolated yet. Clearly the role our genes play in the development of IBD is very complex, and it is not yet well understood.
Want to learn more? See UpToDate's topic, "Epidemiology and genetic and environmental factors in inflammatory bowel disease in adults," for additional in-depth medical information.
Snapper, Scott B; Podolsky Daniel K. "Epidemiology and genetic and environmental factors in inflammatory bowel disease in adults." UpToDate. Accessed: Feb 2010.