There are five types of Crohn's disease, and they are named by where the inflammation resides along the GI tract: Ileocolitis: The most common type, which affects the end of the small intestine and large intestine Ileitis: Affects only the ileum (the last part of the end of the small intestine) Gastroduodenal: Affects the stomach and the duodenum, which resides at the beginning of the small intestine Jejunodeitis: Affects the jejunum in the upper part of the small intestine Granulomatous: Affects the colon