Crohn's disease is somewhat ulcerative colitis. It is a swelling of the gastro-intestinal tract, which can lead to internal bleeding, and severe pain. Some peopel that have Crohn's suffer badly, while some feel very little effects. The disease can go into long remission periods. Most people with Crohns' disease can live productive lives, but i am guessing that it won't cater to being a pro skier.