Role of Tumor Necrosis alpha genes polymorphism TNF-α -308G/A and Monocyte Chemo attractant Protein-1 Promoter 2518G/A as predictive markers for renal failure to develop nephropathy in diabetic patients

There are many diabetes mellitus (DM) patients in the world. About 96% of these are Type 2 DM. Complications of DM are divided into microvascular and macrovascular complications. Microvascular complications; retinopathy, nephropathy, and neuropathy. Macrovascular complications are coronary heart disease, peripheral vascular disease and cerebrovascular diseases. Diabetic nephropathy (DN) is an important health problem as an increasing number of patients develop end-stage renal disease (ESRD). Between 20% and 40% of the newly developing ESRD in the USA is DN. This study provides a summary of the genes and other markers involved in these mechanisms. One molecule that has received considerable attention is the inflammatory cytokine tumor necrosis factor- α (TNF- α). Although the mechanism by which TNF- α exerts these different results is unknown, TNF- α has been shown to have a positive or negative effect on progression to diabetes in NOD mice. This rapid progression to diabetes is related to earlier and more aggressive infiltration of islets by immune cells and an increase in islet antigen presentation in situ by islet antigen presenting cells to T cells in islets. Recent studies suggest that a low-grade inflammatory response may also play a role. Monocyte Chemoattractant Protein 1 (MCP-1), a potent chemokine produced by renal cells, has emerged as a crucial player in this process. Specifically, MCP-1 has been shown to be overexpressed in the kidneys of diabetic animals. Blood samples were collected from al groups, Serum samples separated for TNF-α levels and genomic DNA was extracted from peripheral blood leukocytes for further molecular study to reveal any association between Tumor Necrosis alpha genes polymorphism TNF-α -308G/A and Monocyte Chemo attractant Protein-1 Promoter 2518G/A as predictive markers for nephropathy in diabetic patients. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used for this purpose and digestion of the amplified DNA products by restriction endonuclease (PvuII.and NcoI enzymes) gave fragments with different molecular sizes which express certain genotypes. The distribution analysis showed that the mean age of patients were included in this study their 52.24±10.45years old for diabetic with nephropathy, (55.12±9.65, (24%) of patients without nephropathy. The genotyping of MCP-1 2518G/A revealed three genotypes; the wild homozygous AA type, the heterozygous GA & the mutant homozygous GG type, the frequency of these genotypes(60%,40%,0% in patients and 46.6%, 40%, 13.3% in controls group ) respectively, the A allele also recorded significant different in patients when compare with control group.In MCP-1 2518G/A patients there are no significant different in patients with nephropathy and without nephropathy in all groups of genotype, but there are significant difference according to age groups. Polymorphism TNF-gene-308 gene recorded statically significant different in AA, AG genotype (1.5% ,12.8% respectively), while the GG genotype recorded high present with no significant with healthy group, G allele in patients recorded 92.1% with significant difference when compared with healthy group. In TNF-gene-308 gene there are no significant different in patients groups according to genotype, but there are significant difference according to age groups. The Levels of TNF- α recorded significant difference in all patients TNF- gene-308 gene polymorphism groups (AA,AG and GG. 37.78±7.83, 30.45±3.83 and32.64±5.81respectivelly. In conclusion, this study suggests that the AA, AG genotype and G allele of TNF-gene-308 polymorphism, and the A allele of MCP-1 2518G/A may contribute to the predisposition for diabetic nephropathy.