GENETICS OF DIABETIC RETINOPATHY: STUDY OF VEGF GENE

VEGF is newly discovered growth factor that has diverse biologic properties. The bottom-line of these activities is conduction and orchestration of a series of reactions that are taking place at microvasculature of different tissues/organs. Among the growth factors, cytokines and other mediators that reflect meaningful alteration in their local/systemic level, VEGF is the distinct player which can explain by its own all hemodynamic and architectural manifestations present in diabetic retinopathy (DR). The present study was conducted to pursue the role of a candidate gene structure variation, VEGF gene polymorphisms, in genetic susceptibility/resistance to development of DR through a cross sectional case-control study. The frequency of four SNPs in VEGF gene at positions –7*C/T, –1001*G/C, –1154*G/A and –2578*C/A has been traced among 248 type 1 diabetic subjects (135 DR+, 113 DR−) along with 95 healthy controls. The populations had "British-Caucasian" background and ARMS-PCR technique was employed for DNA genotyping. Comparing the polymorphic variant's frequency at both allelic and genotypic levels among different groups/subgroups, significant difference was noticeable for –7*C/T polymorphism between diabetic patients with vs. without DR, while T allele conferred protective effect (p=0.002; OR=1.98). Contemplating that up-regulation/over-expression of VEGF (local/systemic) as a common pre-requisite for DR development, our hypothesis was that whether the VEGF gene structural variations is correlated with the magnitude of VEGF expression in response to different stimuli present in diabetic context, namely hypoxia and hyperglycemia. Our data indicate that among the examined polymorphisms of VEGF gene, only SNP at position –7*C/T harbored significant difference between DR+ vs. DR− cases, proposing phenotypic impact for that SNP illustrating by evolvement/impediment of DR. However, reminding the insubstantial role of genetic issues in development of DR relative to DN or DNU, replicating current hypothesis by providing larger sample size and also employing more polymorphic markers could shed more light on the subject of present study.