Association of vascular endothelial growth factor A gene (VEGFA) polymorphisms, rs699947 and rs1570360, with diabetic retinopathy and altered VEGF secretion in Pakistani patients with Type 2 diabetes mellitus: A case-control study

Abstract

Background: The incidence of type 2 diabetes mellitus (T2DM) is rising in working age adults in Pakistan. Diabetic patients have a greater chance for developing diabetic retinopathy (DR). There is negligible research on the genetic factors contributing to DR in Pakistani population. This study was done to investigate the association of vascular endothelial growth factor A gene (VEGFA) polymorphisms, 2578 C/A (rs699947) and 1154 G/A (rs1570360) with T2DM, diabetic retinopathy and serum VEGF levels in Pakistani patients. Methods: A case-control study, conducted from Jan 2017 to Dec 2018, including 450 subjects: 150 DR, 150 diabetics without retinopathy (DWR) and 150 healthy controls (HC). Genotyping was done by ARMS-PCR and serum VEGF levels were measured by ELISA. Descriptive and inferential statistics were calculated to compare genotypic / allelic frequencies and biochemical variables. Results: No statistically significant association of rs699947 and rs1570360 genotypic and allelic frequencies were found with DR as compared to DWR. The rs699947 heterozygosity was associated with DWR and homozygous mutant allele A with DWR and DR as compared to HC. Upon stratifying DR into non- proliferative (NPDR) and proliferative (PDR) sub- types, rs699947 AA genotype was significantly associated with PDR as compared to DWR in univariate and multinomial regression analysis. In allelic, dominant and recessive models, the minor allele A showed significant association with DWR and DR as compared to HC. Significantly raised serum VEGF levels were found in DR patients as compared to DWR and were associated with rs699947 and rs1570360 heterozygosity in DWR. Serum VEGF showed a positive correlation with fasting plasma glucose (FPG), cholesterol and LDL-C in DR and DWR groups. rs699947 genotype showed significant association with DWR and DR in Punjabi and Pathan and with DR in Kashmiri ethnic groups compared to HC. rs1570360 was significantly association with DR as compared to DWR in Kashmiri ethnic group. Conclusion: Our study endorses the role of VEGF 2578C/A (rs699947) gene polymorphism in the pathogenesis of T2DM and proliferative diabetic retinopathy in Pakistani patients. Serum VEGF levels have a positive correlation with T2DM and severity of DR.