Just like in other autoimmune diseases it is largely unknown what may cause autoimmune liver diseases. Certainly, a genetic disposition plays a certain, role but it contributes only fairly little to the total risk of disease.
The risk to be affected by the same or a similar disease for family members of patients is less than 5%. For identical twins the risk seems to be higher. Hence, genes do not cause autoimmune liver diseases just by themselves, but they are simply a kind of prerequisite for the disease.
The development of a disease is also dependent on additional factors, but these are as yet not known. Both environmental factors such as nutrition, smoking or contact to toxic substances and infections and psychological factors such as stress or grief have all been suggested and tested, but have so far not been proven to be directly or indirectly responsible or even only contributory for the development of the autoimmune liver diseases.
Only very few indirect findings suggest that some viral infections may partly be the responsible for the development of a disease. In individual cases an autoimmune hepatitis was seen only a few weeks of months after an acute viral hepatitis. However, a direct connection between previous and hence responsible or triggering infections has so far not been demonstrated convincingly.