Crohn's disease involves inflammation of the gastrointestinal (GI) tract and most commonly affects the terminal ileum or colon. Because Crohn's disease can occur in various areas of the GI tract, disease activity and severity can vary widely over time, with symptoms ranging from mild to severe and depending on the location in the GI tract at which the disease is active. Crohn's disease is a chronic, incurable disease with low mortality that is generally diagnosed in adolescence and early adulthood.
Crohn's disease is currently an idiopathic condition, the pathogenesis of which is yet to be fully elucidated. However, it is known to involve an interaction between genetics, the immune system, and environmental factors. Risk factors include ethnicity, smoking, family history, antibiotic or non-steroidal anti-inflammatory agent use, and diet.
It is estimated that in 2015, there were 1.4 million diagnosed prevalent cases of Crohn's disease in the US, Japan, and five major EU markets (France, Germany, Italy, Spain, and the UK). Over 2015-35, the number of prevalent cases is expected to increase by 16.9% to 1.6 million.