Inflammatory bowel disease has two different types of diseases which is ulcerative colitis and Crohn's disease. The NOD2 gene is an IBD risk gene which was observed in 2001. There have been 163 risk genes or loci that have been identified and are associated with both Crohn's disease and ulcerative colitis. After the second World War, the rates have increased with IBD in northern Europe and North America. The risk of IBD in an offspring increases dramatically if both parents have IBD. For the population, there are different percentages of who gets it which is shown in the image above. The symptoms of IBD include abdominal pain, diarrhea, loss of appetite, etc.