Association of IGF-I gene polymorphism with diabetic nephropathy in Egyptians with type 2 diabetes

Abstract

Background Genetic-based studies are being carried out worldwide to identify the susceptibility genes for diabetic nephropathy (DN), which represents a major health problem in all diabetics. Aim To study the association between genotypes of insulin-like growth factor-1 (IGF-1) and DN among Egyptian patients with type 2 diabetes and if there is any possible relation between these polymorphisms and different variables. Patients and methods A total of 26 diabetics without nephropathy (group 1) and 26 with nephropathy (group 2), with an average age of 52.7±6.1 years, and 25 age-matched and sex-matched healthy participants (control group) were included. Two tagging single nucleotide polymorphisms were assessed in IGF-1 gene: rs6214 and rs10860860. Genotypic distribution was tested for Hardy–Weinberg equilibrium. The genotype was evaluated using the χ2 tests. Fasting blood glucose, glycated hemoglobin, uric acid, lipid profile, serum creatinine, and urine albumin–creatinine ratio were assessed. Results The distribution of IGF-1 gene polymorphisms reflects a significant association with DN, where the frequency of variant genotype GG in polymorphism rs6214 was found to be significantly higher in diabetics with nephropathy than other groups [odds ratio (OR)=20.57; 95% confidence interval, 2.25–74; P=0.001). Moreover, the frequency of variant AA in polymorphism rs10860860 was also found to be significantly higher in diabetics with nephropathy (OR=7.37; 95% confidence interval, 1.87–30.07; P=0.001). However, GA and AT alleles were found to be associated with ORs less than 1 in diabetics with nephropathy when compared with other groups (P=0.002 and 0.007, respectively), which means that it could be significantly protective against DN. where they found to be significantly higher in diabetics with genotype GG than those with genotype GA (P=0.13, 0.11 respectively). Conclusion The variants of IGF-1 rs6214 and rs10860860 could entail a risk of DN in Egyptians with type 2 diabetes mellitus. It means that the type of IGF-1 gene polymorphism is responsible for the susceptibility of DN more than its serum level.