However, a common causative pathway to PBC, if it exists, could not yet be identified, and it is still controversial which of the outlined factors predispose most to PBC. It may well be speculated that the search for "the cause" of PBC might lead into the dark, and the identified pathogenetic factors may contribute to a different extent in each patient. Why should the cause of PBC not be variable as is the clinical picture? The latter is highly variable: We define PBC today as the presence of cholestasis and AMAs, but only 90-95% of patients are AMA-positive and some AMA-positives hardly develop PBC. Most patients respond to UDCA treatment, but one third does not and disease progression is highly variable, to mention only the most obvious variabilities. The clinical picture that, by convention, we call PBC may well emerge from an individual composition of the described and other pathological factors.