CTLA4 gene polymorphisms associated with insulin-dependent diabetes mellitus (IDDM) type I in Iraqi population

T study was correlated to evaluate polymorphisms in CTLA4 associated with insulin-dependent diabetes mellitus in a Iraqi population. Blood samples were collected from 40 patient (4-25 years) from 1/6/20101/2/2011, isolation of DNA were done and PCR was performed using primer for CTLA4 gene. The result shows that 31 patients have mutation in 49 position A/G polymorphism in exon 1 of CTLA4 by using BstEII enzyme. There is a highly significant correlation between diabetes and incidence of A/G 49 position in exon 1 of CTLA4 gene (X2 = 32.1, P>0.05), the conclusion is that there is enough evidence to support the claim that diabetes is related to A/G 49 transition mutation. Keyword : CTLA4 gene , insulin-dependent diabetes mellitus C T-lymphocyte antigen 4 (CTLA4) also known as CD152 (Cluster of differentiation 152) is a protein that plays an important regulatory role in the immune system. CTLA4 is a member of the immunoglobulin superfamily, which is expressed on the surface of Helper T cells and transmits an inhibitory signal to T cells. The cytotoxic T lymphocyte-associated antigen 4 gene (CTLA4) encodes the T cell receptor involved in the control of T cell proliferation and mediates T cell apoptosis [1]. In humans, the CTLA4 protein is encoded by the CTLA4 gene [2]. The receptor protein is a specific T lymphocyte surface antigen that is detected on cells only after antigen presentation. Thus, CTLA4 is directly involved in both immune and autoimmune responses and may be involved in the pathogenesis of multiple T cell-mediated autoimmune disorders [3]. The human CTLA4 gene was mapped to chromosome 2q33. It consists of three exons, the first encodes a V-like domain of 116 amino acids. Substitution of A-to-G at nucleotide 49 in exon 1 results in an amino acid substitution (Thr/Ala) in the leader peptide of the protein [4]. Type 1 diabetes mellitus (TIDM) and insulin dependent diabetes mellitus (IDDM) is a common multifactorial autoimmune disease that arises from specific destruction of insulin secreting beta cells of the islets of langerhans by autoreactive T-lymphocyte [5], the pathogenesis of IDDM is complex and multifactorial involving interaction between both genetic and environmental factors [6], mutation and polymorphisms leading to altered activity of CTLA4 are believed to play an important role in the risk of developing autoimmunity [7]. The present study aimed to investigate correlation between the +49 A/G polymorphism in exon 1 of CTLA4 gen and increasing insulin-dependent diabetes mellitus (IDDM) type I in Iraqi population Sample collection: Whole blood samples was obtained from 40 Iraqi patients affected by IDDM (20 male and 20 female(, age ranged 4-25 years and also obtained from healthy used as a control group. Whole blood (4ml) was collected into an EDTAtube; the samples were stored at -20°C until further processing. DNA extraction DNA was extracted from the samples by wizard genomic (DNA purification kit, Promega) according to the isolating genomic DNA from whole blood protocol. DNA extracted Introduction: Corresponding Address: Najwa Sh. Ahmed Genetic engineering and Biotechnology Institute, Baghdad Email: Najawa2025@yahoo.com Material and Methods: