Many studies have shown that cytotoxic T lymphocyte antigen-4 (CTLA-4) gene variants are associated with several autoimmune diseases particularly type 1 diabetes. Due to the lack of consistent data for this association with type 2 diabetes (T2D), this study explored the possible influence of CTLA-4 gene polymorphisms at -1722 (T/C), -318 (C/T), and +49 (G/A) positions for susceptibility to T2D in relation with neuropathy. One hundred and eleven unrelated patients with T2D [49 patients with diabetic peripheral neuropathy (DPN) and 62 patients without PDN] and 100 healthy ethnic- and gender-matched controls were included in this study. The dimorphisms at -1722 (C/T), -318 (C/T) and +49 (A/G) for CTLA-4 gene were determined using ARMS-PCR. The CTLA-4 (+49 G/G) and (+49 A/A) genotypes were found to be positively and negatively associated with T2D, respectively (p=0.03). The -318 C/T and T/T genotypes were more frequent in patients than controls and -318 C/C genotype was shown to be protective for T2D (p=0.003). ACT and GTT Haplotypes were less and more frequent in controls and patients, respectively (p=3.86×10-7 and p=2.29×10-5). Genotypes distribution among T2D patients with and without DPN compared to healthy controls showed significantly lower frequencies for -318 C/C and +49 A/A genotypes and significantly higher frequencies for -318 C/T and T/T genotypes as well. Our findings indicate that CTLA-4 (+49 A/G) and (-318 C/T) genotypes could be considered as genetic risk factors associated with susceptibility or protection for T2D.
Keywords: CTLA-4 antigen; Diabetes mellitus Type 2; Genes.