Primary biliary cirrhosis and autoimmunity: evaluating the genetic risk.

The genetic basis of autoimmunity is receiving increased attention. Organ-specific diseases, such as primary biliary cirrhosis, may be considered model diseases to use for development of databases and extrapolation to other autoimmune diseases. PBC is an enigmatic autoimmune disease that predominantly affects females and leads to destruction of intrahepatic bile ducts. The serologic hallmark of this disease is anti-mitochondrial antibodies that specifically react with the E2 components of 2-oxodehydrogenase enzymes, including PDC-E2. There are no clear major histocompatibility complex associations with the development of PBC, despite the observation that first-degree relatives of index patients with PBC have a 4-6% prevalence of development of PBC. This risk factor is comparable or higher than any other human autoimmune disease and suggests that a genome-wide approach towards dissection of genetic associations would lead to valuable new insights. In this review we place these concepts in perspective and highlight in particular the genetic associations in primary biliary cirrhosis.