Genetic Studies of Inflammatory Bowel Disease

This study will examine the existence of genetic regions that are believed to bring about a risk for inflammatory bowel disease (IBD), with its subtypes of Crohn's disease and ulcerative colitis. It will identify the locations of chromosomes responsible for hereditary IBD through linkage analysis, a technique in genetic research in which the occurrence of a disorder in a family is evaluated alongside a known genetic disorder. The project will also do fine mapping of genes and examine possible genes associated with IBD.

IBD is a chronic and often disabling disorder of the gastrointestinal tract, affecting about 500,000 Americans. Both Crohn's disease and ulcerative colitis share many characteristics, such as abdominal pain, bloody diarrhea, fever, fatigue, and malnutrition. But the main factors that distinguish these subtypes depend on the location and depth of inflammation. Tests and analyses can generally pinpoint some of the differences between the two, but sometimes there are major overlaps in characteristics, and the diagnosis is known as indeterminate IBD. The exact cause of IBD is not known, but genetic and environmental factors are known to contribute to risk for the disease. The single most important environmental risk factor has been smoking exposure at the time the diagnosis is made. Also, several genetic risk factors are ethnicity, family history, and polymorphisms-abilities to take on different forms-in the NOD2 gene.

Patients who have a diagnosis of IBD and their family members 5 years of age and older who have or do not have that diagnosis may be eligible for this study.

Participants will be asked to complete a questionnaire on their health, ethnic background, religion, habits, family medical history, and medications. Information will also be sought on the diagnosis, course, complications, and treatment of IBD, as well as risk factors. In addition, there will be collection of blood to be used for DNA preparation, storage of lymphocytes, and information on immunology.