The Role of CTLA-4 Gene Polymorphisms in Autoimmune Disease Pathogenesis: A 2012 Update

Gene association studies are very appealing in autoimmune diseases. In recent years, access to other human gene sequences prompted investigators to focus on genes encoding the immune regulatory proteins such as the costimulatory, adhesion molecules, cytokines and chemokines and their receptors. Among them, cytotoxic T-lymphocyte antigen-4 (CTLA-4) has been extensively studied for its pivotal role in autoimmunity. As a central regulatory element of the immune responses magnitude, CTLA-4 could act as a double-edged sword and only the optimal expression ensures an effective, but at the same time, safe immune response. Thus, we can argue that CTLA-4 alleles associated with abnormal membrane expression could make a person more susceptible to tumor growth and/or manifestation of autoimmune diseases. Unfortunately, the relationship between the presence of SNP conferring susceptibility/protection to autoimmune disease and the genetic regulation/modification of CTLA-4 is the not yet fully clarified, and in some aspects conflicting.