I am 25 years old and have a 29-year-old brother with Crohn's disease. I have heard that Crohn's runs in families and that you're much more likely to get it if a sibling has been diagnosed with it. I want to take any action I can to prevent it. At this point in my life, I do not have any regular symptoms that lead me to believe that I should be seeing a doctor. Am I in the clear? Or should I still be worried? If so, is there anything I can do to help prevent Crohn's?
Crohn's disease does run in families, probably because of certain genetic mutations that get passed on through the generations. Unfortunately, we do not know all of the genetic mutations associated with Crohn's disease. Also, even if a known genetic mutation exists in a family, not everyone with the mutation will develop Crohn's disease. Therefore, it's not useful to test for mutations known to be associated with Crohn's disease, such as the NOD2/CARD15 gene on chromosome 16.
The lifetime risk that first-degree relatives of Crohn's disease patients will develop Crohn's disease themselves is just 1 percent. Therefore, if you and your brother had 98 other siblings, just one would be expected to develop Crohn's disease! Even though this risk seems low, it is much higher than the expected lifetime risk of developing Crohn's disease in the general population.
It would behoove you to see a doctor if you develop possible Crohn's symptoms, such as abdominal pain, diarrhea, or weight loss. The best preventive measure you can take is to quit smoking cigarettes or never start. Cigarette smoking is associated with Crohn's disease, and quitting has been shown to be associated with a less aggressive course of the disease.