For other's information: jpmc must be describing Ulcerative Colitis here, not Crohn's disease. So little is known about the underlying cause of UC and Crohn's that it's not clear that they are two distinct diseases; there appear to be cases that border between the two, although there is definitely a bi-modal clustering of symptoms. But, to my understanding, the characteristic of UC that most clearly distinguishes it from Crohn's is that UC is confined to the colon (large intestines), while Crohn's may effect the entire digestive tract. So, removal of the colon is a life-altering but effective cure for UC. On the other hand, removing the colon may be medically necessary for a patient suffering from Crohn's, but it's certainly no cure.