Inflammatory Bowel Disease (IBD) is a group of conditions of the gastrointestinal tract with chronic or recurring immune response and inflammation. The two most common types are Ulcerative Colitis (UC) and Crohn’s Disease (CD). In Ulcerative Colitis the affected area is limited to the primary mucosa of the large bowel. Usually, there is a continuous area of inflammation that arises from the rectum and extends to the rest of the colon. In Crohn’s Disease, transmural lesions may occur at any part of the gastrointestinal tract, with the terminal ileum and colon being the areas most typically involved.  CD is characterized by skip lesions with chronic inflammation of all intestinal layers, which can lead to fistulae, strictures, and microperforations. Other types of IBD include Indeterminate Colitis (IC) and Inflammatory Bowel Disease Unclassified (IBDU). These are considered more as temporary diagnoses when the difference between UC and CD cannot be determined at the time of presentation.

In the United States, about 1 – 1.3 million people suffer from IBD. Although IBD can affect people of all ages, the peak age of onset is between 15 and 30 years old. IBD is more prevalent in developed countries and urban areas. In general, men and women appear to be equally affected by IBD. However, some studies report slight differences, with Ulcerative Colitis being more common in males and Crohn’s Disease more frequent in women.  The exact cause of IBD is not entirely understood, but it is known to involve an interaction between genes, the immune system, and environmental factors.

NIDDK IBD Genetics Consortium

The IBD Center, Mount Sinai Hospitals

Crohn’s & Colitis Foundation of America

The Ashkenazi Genome Consortium

Research Match

NIDDK (Crohn’s Disease)

NIDDK (Ulcerative Colitis)