Cytotoxic T lymphocyte antigen-4 gene polymorphisms do not confer susceptibility to autoimmune hepatitis types 1 and 2 in Brazil.

Abstract

Susceptibility to autoimmune hepatitis (AIH) has been linked to different HLA-DR antigens in distinct populations. Recently, an A-G polymorphism in exon 1 of the cytotoxic T lymphocyte antigen-4 (CTLA-4) gene was associated with predisposition to AIH type 1 (AIH-1) in white individuals in North America. This polymorphism has been associated with several other autoimmune diseases, presumably because of its effect in the expression of CTLA-4, an adhesion molecule that downregulates peripheral T cell responses. The aims of this study were to assess the frequency of CTLA-4 genotypes in Brazilian patients with AIH-1 and AIH type 2 (AIH-1), as well as to investigate the influence of these genotypes in disease expression. Determination of CTLA-4 genotypes was carried out in 106 patients with AIH-1, 26 subjects with AIH-2, and 67 healthy control subjects by polymerase chain reaction (PCR)-based techniques. No difference in the distribution of CTLA-4 genotypes was observed in subjects with AIH-1 and AIH-2 as compared to healthy controls. Patients with AIH-1 and AIH-2 with the GG genotype exhibited lower gamma-globulin and ALT levels, respectively. Susceptibility to AIH-1 and AIH-2 in Brazilian patients is not influenced by exon 1 CTLA-4 gene polymorphisms at position 49.