The cause of primary biliary cirrhosis is unknown. Most research suggests the disease is an autoimmune condition. The immune system usually protects the body from harmful substances such as bacteria and viruses by attacking and destroying them. In autoimmune diseases, the immune system instead attacks the body’s own tissues. In primary biliary cirrhosis, the immune system attacks the bile ducts.
Genetic factors may make a person prone to develop primary biliary cirrhosis. Primary biliary cirrhosis is more common in people who have a parent or sibling—particularly an identical twin—with the disease.
Genetic factors may also make some people prone to develop other autoimmune diseases. People with primary biliary cirrhosis may have other autoimmune conditions such as rheumatoid arthritis or autoimmune thyroiditis.
A person who has genetic factors for primary biliary cirrhosis may be more likely to develop the disease after exposure to chemicals or infections, such as urinary tract infections.