ABSTRACT
Type 1 diabetes is an autoimmune disease characterized by T-cell mediated destruction of pancreatic ?-cells. A variety of environmental and genetic factors are involved in the development of the disease. IL-12 is a cytokine secreted by different cells and plays and important role in cell-mediated immune responses and maintenance of cytokine network balance. Genetic polymorphisms in the IL-12 gene were shown to interfere with the transcriptional activity of the IL-12 gene, and this influences the production, secretion or activity of IL-12 growth factor. In this study the polymorphism in the 3'-untranslated region of the IL12Bgene encoding IL-12 p40 was investigated. In this case control study 75 type 1 diabetic patients who had definitely been diagnosed at least 2 years before sampling and were under Insulin therapy, recruited. A total of 88 healthy controls selected from voluntarily blood donors who had referred to IRAN Blood Transfusion Organization. DNA extracted from whole blood and polymorphism at +1188 nucleotide was assessed by SSP-PCR. Data were analyzed by SPSS, using chi- square test with 95% confidence interval. A statistical significance of AA presence [57%] at the +1188 3'-UTR position of IL-12 B gene in patients was found, after genotyping, compared to the control group[p<0.05]. Interleukin-12 [IL-12] is a key cytokine for the induction of Th1 immune responses. Polymorphism in the 3'-UTR of the IL-12 p40 gene and association with susceptibility to Diabetes type I evaluated. AA genotype was more frequent than AC and the AC more common than CC in diabetic patients. In another word, the A allele of the [A/C] polymorphism at position +1188 in the 3'-UTR found to be preferentially transmitted to people with type I diabetes.These polymorphisms may affect gene transcription of IL-12 p40, causing individual variations in cytokine production. A better understanding of the molecular mechanisms, will give us the opportunities to develop new and effective therapeutic approaches