Can cause Crohn's disease

Crohn's Disease, Causes & Risk Factors

What is Crohn's Disease?

Crohn's disease is a chronic inflammatory bowel disease. In contrast to ulcerative colitis, Crohn's disease can inflame the mucous membrane of the entire digestive tract from the oral cavity to the anus. Most often, however, it affects the last part of the small intestine, the so-called terminal ileum. The cause of the disease is so far unknown. Experts suspect that some patients have an inherited predisposition to the disease, as well as infections or disorders in the immune system. In contrast to ulcerative colitis, Crohn's disease can be alleviated but not cured by treatment.

The disease progresses in phases. Phases without inflammation with little or no discomfort alternate with attacks of inflammation with more or less pronounced symptoms. The disease progresses very differently from patient to patient.

In Germany, around 120 to 200 people per 100,000 population suffer from Crohn's disease. Every year 5 people per 100,000 inhabitants in Germany develop the disease anew. Most patients are between 20 and 30 years old when the disease first develops.


Despite intensive research, it has not been clarified why people develop Crohn's disease. Probably several causes contribute together to the onset of the disease. Some of the cases are hereditary: 20% of patients with Crohn's disease have an altered gene (mutation) in their genetic make-up.

The immune system also seems to play a role. In people with Crohn's disease, it is caused by unknown triggers, such as: B. viruses or bacteria activated. The immune system reacts more strongly than in healthy people and thereby causes inflammation in the intestinal wall.

Diet and smoking can also affect the development of Crohn's disease. For example, smokers are more likely to develop Crohn's disease than non-smokers.

Risk factors

People with certain genetic changes (mutations) are at increased risk of Crohn's disease. About half of the patients with Crohn's disease have mutations in the NOD2 gene (= CARD15). The level of risk depends on how severe the changes are and whether both genes are changed. If a person has a mutation in a NOD2 gene, the risk of Crohn's disease is around 2.5 times higher than that of people without this mutation. With two changes within the same gene, the risk increases about 40 times. If both NOD2 genes are changed, the risk is 100%. Mutations in other genes can also influence the risk of Crohn's disease: People with changes in the DLG5 or OCTN1 gene have a higher risk of developing the disease.

It is not exactly known how large the influence of other risk factors on the development of the disease is. However, it is known that smokers are more likely to develop Crohn's disease than non-smokers.