The paper presents the current state of research on the prevalence of the most commonly described polymorphism CTLA-4 gene at position 49 (G49A) in exon autoimmune diseases. Briefly discussed the mechanism of negative regulation of the immune response, in which the role of CTLA-4 (CD152). The structure CTLA-4 gene and presents the results of gene polymorphism in Addison's disease, insulin-dependent diabetes type I, Graves' disease, Hashimoto's disease, and multiple sclerosis.