<prompt> Crohns disease can be seen in -Jejunum onlyColon onlyTerminal ileum and right sideMouth to anus  <response>: Chronic, transmural inflammatory disease of the GIT for which the cause is unknown. Can involve any part of the alimentary tract from the mouth to the anus but most commonly affects the small intestine and colon Involvement of both large and small intestine: 55 Involvement of only small intestine: 30 Involvement of only large intestine: 15 Crohns disease primarily attacks young adults in the 2nd and 3rd decades of life. More common in smokers and urban dwellers Two genders are affected equally with strong familial association Upper GI Crohns disease is most frequently found in the gastric antrum and duodenum. In patients with colonic disease, rectal sparing is characteristic.Etiology: Unknown Infectious agents proposed as potential causes: Mycobacterium paratuberculosis and measles virus. The identification in 2001 of the CARD-15NOD2 mutation on chromosome 16q, also known as IBD-1 locus provided the first definitive genetic link to the condition and is relatively specific for Crohns disease. 