ARTHUR HELLER, MD: Ulcerative colitis is a disease that starts in the rectum, the lowest-most part of the colon, and in a continuous manner can work its way up to a varying degree in the colon. Crohn's disease can affect the gut anywhere from lips to anus, often in a skip pattern, a segmental pattern.
Ulcerative colitis affects inflammation of only the superficial lining cells of the colon, whereas Crohn's disease involves inflammation of the full thickness of the gut.
BETTINA GREGORY: Dr. Tepper, what are the causes of IBD?
ROBERT TEPPER, MD: No one knows the specific cause. Currently, the most attractive theory is that in a genetically predisposed person there is some environmental trigger that causes an abnormal immune response. Of the factors involved, there are certainly genetic factors.
We know this because of patients who have IBD, in 15% of them, they will be able to identify a first-degree relative, a parent, child or sibling, who also has the disease. Secondly, we know that identical twins are more likely to both have the condition than non-identical twins.
We know that there are certain ethnic groups, such as Ashkenazi Jews, who are more likely to have the condition than others. And finally, there's been a recent discovery of a gene called the nod-2 gene, which is twice as likely to occur in Crohn's patients than in patients who do not have the disease.
BETTINA GREGORY: You've been talking about the genetic factors, and you did mention that certain groups, such as the Ashkenazi Jews, are more prone than the general population to have this disease. But can you mention any other populations of who is likely to get it, such as men or women, old or young, things like that?