Some types of autoimmune hepatitis have no clearly identified cause, while others are associated with known agents such as thienic acid (a diuretic) or with diseases such as hepatitis C and D. In general, autoimmune hepatitis of unknown etiology has a more dramatic clinical picture, with higher serum transaminase activity and γ-globulin levels, liver histology suggesting higher activity than in cases of known etiology, and a better response to corticosteroid therapy.