<P> While the cause of Crohn 's disease is unknown , it is believed to be due to a combination of environmental , immune , and bacterial factors in genetically susceptible individuals . It results in a chronic inflammatory disorder , in which the body 's immune system attacks the gastrointestinal tract possibly directed at microbial antigens . While Crohn 's is an immune - related disease , it does not appear to be an autoimmune disease ( in that the immune system is not being triggered by the body itself ) . The exact underlying immune problem is not clear ; however , it may be an immunodeficiency state . About half of the overall risk is related to genetics with more than 70 genes found to be involved . Tobacco smokers are twice as likely to develop Crohn 's disease as nonsmokers . It also often begins after gastroenteritis . Diagnosis is based on a number of findings including biopsy and appearance of the bowel wall , medical imaging and description of the disease . Other conditions that can present similarly include irritable bowel syndrome and Behçet 's disease . </P>
<P> While the cause of Crohn 's disease is unknown , it is believed to be due to a combination of environmental , immune , and bacterial factors in genetically susceptible individuals . It results in a chronic inflammatory disorder , in which the body 's immune system attacks the gastrointestinal tract possibly directed at microbial antigens . While Crohn 's is an immune - related disease , it does not appear to be an autoimmune disease ( in that the immune system is not being triggered by the body itself ) . The exact underlying immune problem is not clear ; however , it may be an immunodeficiency state . About half of the overall risk is related to genetics with more than 70 genes found to be involved . Tobacco smokers are twice as likely to develop Crohn 's disease as nonsmokers . It also often begins after gastroenteritis . Diagnosis is based on a number of findings including biopsy and appearance of the bowel wall , medical imaging and description of the disease . Other conditions that can present similarly include irritable bowel syndrome and Behçet 's disease . </P>
name an organ and / or system that can be affected by a genetically-linked condition
name an organ and / or system that can be affected by a genetically-linked condition
the gastrointestinal tract
the gastrointestinal tract