Genetic studies on CTLA4 in T1D have been focusing on three gene variants: the A49G SNP (rs231775, OR=2.000) in exon 1, the SNP rs3087243 (OR=0.840) which is in high linkage disequilibrium with the dinucleotide (ATn) repeat in the 3’- untranslated regions (UTR) and the coding C318T SNP (rs5742909, OR=1.500) in the CTLA4 promotor (128). Here, CTLA4 is linked to type 1 diabetes mellitus.