Primary biliary cirrhosis (PBC) is a disease of the liver, which predominantly affects women. It causes slowly progressive liver disease, which eventually causes liver failure, requiring a liver transplant. Several different studies of large patient cohorts indicate that the cause of this disease is likely due to a combination of factors including genetic and environmental. PBC is associated with several other "autoimmune diseases" - recently a gene has been identified to be abnormal in individuals with another autoimmune liver disease, namely rheumatoid arthritis. This gene usually tells the body when to switch off an immune response. This study plans to identify whether individuals diagnosed with PBC have a similar abnormality in this gene called protein Tyrosine Phosphatase.