Genetic background of primary biliary cirrhosis

The clustering of patients in a representative family as well as relatively high concordance rate in monozygotic twins strongly indicate that genetic factors play a crucial role in modulating primary biliary cirrhosis (PBC) by conferring susceptibility to, or providing protection from, the disease. Therefore, much like other autoimmune diseases, intensive investigations have attempted to elucidate which genes are incriminated in the etiology of PBC. So far, a number of genes, including major histocompatibility complex (MHC) class I and II, cytokines and cell surface molecules, have been examined to seek the possibility of whether single nucleotide polymorphisms (SNP) of the gene might be associated with susceptibility to PBC. Nevertheless, it appears that methodologicaldifficulties, mainly the limitation of the number of individuals tested in each study, hamper the detection of a convincing and reproducible link between genetic polymorphisms and the etiology of PBC. Also, the difference in genetic background among several ethnic groups may play a role in concealing the association. In this review, I will highlight the genetic association in PBC, and review the association of genetic polymorphisms with the etiology of PBC, which have been reported in various ethnicities.