RESUMO
Objective To investigate the association of cytotoxic T lymphocyte associated antigen 4 (CTLA 4) gene polymorphism with type 1diabetesmellitusandautoimmunethyroiddiseases. Methods The A/G phenotype at position 49 of the CTLA 4 gene exon 1 was determined by PCR RFLP method in 33 classic type 1 diabetes patients, 57 latent autoimmune diabetes in adults (LADA) patients, 122 autoimmune thyroid disease patients and 84 healthy control subjects of Chinese Han. Results The frequency of the CTLA 4 G phenotype was significantly higherintype1diabetespatientsthanthatincontrol subjects (55.6% vs 36.9%, P=0.0005). Neither the presence nor the absence of G allele influenced the occurrence of islet autoantibody (ICA) and glutamate decarboxylase antibody (GADA). The strong association of the CTLA 4 G allele with AITDs was showed in our study (66.4% vs 36.9%, P