CD152 antigen (Cytoto, Xenopus/Amphibian,ic T-lymphocyte protein 4, CTLA-4) binds to B7-1 (CD80 antigen) and B7-2 (CD86 antigen), resulting in T-cell activation. Genetic variation in CD152 influences susceptibility to systemic lupus erythematosus (SLE). SLE is a chronic, inflammatory and often febrile multisystemic disorder of connective tissue. SLE affects principally the skin, joints, kidneys and serosal membranes. SLE is thought to represent a failure of the regulatory mechanisms of the autoimmune system. Mutations in CD152 have been associated with insulin-dependent diabetes mellitus, Graves disease, Hashimoto thyroiditis, celiac disease, thyroid-associated orbitopathy, and other autoimmune diseases.