Abstract
The aim of this work was to study the polymorphism in CTLA4 gene in insulin-dependent diabetes mellitus (IDDM) type I patients in Baghdad population. To achieve this goal, blood samples were collected from 80 IDDM (40 males and 40 females) and 20 samples of healthy, DNA was isolated and the CTLA4 gene (A 152 bp fragment) were amplified by using specific primers for exon1 of this gene, and then found the sequence of this region. The DNA sequencing results of flank sense of CTLA4 gene from healthy patients was found to be compatible (100%) with wild type of Homo sapiens from the Gene Bank, while 99% compatibility were found for the gene from 70 IDDM cases patients with wild type of gene. The difference may be attributed to one transition mutations, A/G at position 49 of the CTLA4 gene (from AGC to AAC). It is a missense mutation that leads to changes in amino acid from serine (S) to asparagine (N). Our results showed that the incidence of A/G mutation at nucleotide position 49 and diabetes was highly significant (X2 = 100, P 0.05). In conclusion, our case study suggests that the +49 A/G SNP of the CTLA4 gene is strongly associated with genetic susceptibility to type 1 diabetes mellitus in the Baghdad/Iraqi population. Key words: CTLA4 gene, insulin-dependent diabetes mellitus, A/G polymorphism.
Highlights
Cytotoxic T-lymphocyte antigen 4 (CTLA4) known as cluster of differentiation 152 (CD152) is a protein that plays an important role in the immune system regulations
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
Whole blood samples were obtained from 80 Baghdad patients affected by insulin-dependent diabetes mellitus (IDDM) (40 males and 40 females, age ranged from 4 to 25 years)
Summary
Cytotoxic T-lymphocyte antigen 4 (CTLA4) known as cluster of differentiation 152 (CD152) is a protein that plays an important role in the immune system regulations. 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 CTLA4 encodes the T cell receptor involved in the control of T cell proliferation and mediates T cell apoptosis (Yanagawa et al, 1997; Larsen et al, 1999). The receptor protein is a specific T lymphocyte surface. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. The membranebound isoform functions as a homodimer which is interconnected by a disulfide bond, while the soluble isoform functions as a monomer (Kristiansen et al, 2000)
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