Why does Crohn's disease occur?
The exact cause of Crohn's disease is unknown. However, research suggests a combination of factors may be responsible. These include: genetics – genes you inherit from your parents may increase your risk of developing Crohn's disease the immune system – the inflammation may be caused by a problem with the immune system (the body's defence against infection and illness) that causes it to attack healthy bacteria in the gut previous infection – a previous infection may trigger an abnormal response from the immune system smoking – smokers with Crohn's disease usually have more severe symptoms than non-smokers environmental factors – Crohn's disease is most common in westernised countries such as the UK, and least common in poorer parts of the world such as Africa, which suggests the environment (particularly sanitation) has a part to play