Are increased individual susceptibility and environmental factors both necessary for the development of primary biliary cirrhosis?

A daughter, her mother, and an unrelated close friend developed primary biliary cirrhosis (PBC). The mother and the close friend nursed the daughter through her terminal illness and presented with PBC PBC within 21 months after her death. Half of the asymptomatic first-degree relatives in the two families had serum autoantibodies, including one with antimitochondrial antibody, suggesting some genetic susceptibility to abnormal immune reactions. It is concluded that some environmental factor may be present in PBC, perhaps in addition to a genetic susceptibility to that factor.