name an organ and/or system that can be affected by a genetically-linked condition
Crohn's disease 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.[6][7][8] It results in a chronic inflammatory disorder, in which the body's immune system attacks the gastrointestinal tract possibly directed at microbial antigens.[7][9] 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).[10] The exact underlying immune problem is not clear; however, it may be an immunodeficiency state.[9][11][12] About half of the overall risk is related to genetics with more than 70 genes found to be involved.[1][13] Tobacco smokers are twice as likely to develop Crohn's disease as nonsmokers.[3] It also often begins after gastroenteritis.[1] Diagnosis is based on a number of findings including biopsy and appearance of the bowel wall, medical imaging and description of the disease.[1] Other conditions that can present similarly include irritable bowel syndrome and Behçet's disease.[1]