CTLA4 and autoimmune disease: T1DM is one of the most frequent chronic diseases in children, and has become health problem in developing countries.17Recently, associated studies have been conducted to address the association of polymorphisms in the CTLA-4 gene as a candidate gene with several autoimmune diseases,6particularly T1DM.7The CTLA-4 +49A/G gene polymorphism was found to be the only known SNP that causes an amino acid exchange (threonine to alanine or +49 A/G) in exon 1 in the leader peptide sequence of the CTLA-4 protein, which can be associated with altered protein expression4and T cell activation.5