Association of VEGF and eNOS gene polymorphisms in type 2diabetic retinopathy

[摘要] Purpose: Vascular endothelial growth factor (VEGF) is a majormediator of angiogenesis, and nitric oxide (NO) is an upstream anddownstream regulator of VEGF mediated angiogenesis. VEGF and NO havebeen suggested to play an important role in the pathogenesis ofmicrovascular complications in diabetic retinopathy (DR). The objectiveof this study was to examine the genetic variations of the VEGF andeNOS gene and assess their possible relationship to DR in type 2diabetic patients in the Indian population.Methods: In this study, 210 unrelated patients were enrolled andcategorized into two study groups: a DR group, consisting of patientswith proliferative diabetic retinopathy, and a diabetic withoutretinopathy (DWR) group comprised of patients with type 2 diabetes ofmore than 15 years duration who showed no signs of DR or had fewer thanfive dots or blot hemorrhages. Association of the genetic polymorphismsin the promoter and 5' UTR region of VEGF and the intron4 region ofeNOS were studied. Total genomic DNA was isolated from peripheralblood leukocytes. PCR-RFLP analysis was performed for all samples toevaluate the genotypes. The distributions of the genotypes were comparedusing the χ2 test. Haplotype estimation and multiple logisticregression analysis were carried out to analyze the significance ofpolymorphisms.Results: We investigated four reported polymorphisms in the VEGF(5' UTR, promoter) and one reported polymorphism (intron 4) in theeNOS gene in Type 2 diabetes patients with (n=120) and without(n=90) retinopathy. The genotype distribution of the C(-7)T, T(-1498)C,and C(-634)G polymorphisms of VEGF differed significantly betweenpatients with DR and DWR (p=0.001, p=0.0001, and p=0.021, respectively).Allele C in the -1498 region (p=0.0001) and T in -7 region (p=0.002)were also found to be significantly increased in patients withretinopathy. Calculated odds ratios (OR) for three heterozygousgenotypes of C(-7)T, T(-1498)C, and C(-634)G regions were 4.17 (95% CI:1.90-9.18, p=0.0001), 4.37 (95% CI: 2.44-7.84, p=0.0001), and 2.33 (95%CI: 1.24-4.36, p=0.008), respectively, and was found to be significantlyhigher in the DR group when compared with the DWR group. Multiplelogistic regression analysis revealed that the nongenetic parameters,age (p=0.024) and duration of diabetes (p=0.009), and the geneticparameters, like VEGF C(-7)T (p=0.002) and T(-1498)C (p=0.001)polymorphisms, were significantly associated with DR. The frequencies ofhaplotype consisting of the majority of alleles in VEGF were foundto be significantly associated with DR. The genotype distribution ofeNOS did not differ significantly between the two study groups, andtherefore the eNOS intron 4 polymorphism was considered to be lesssignificant.Conclusions: This is the first study to report VEGF and eNOSgene polymorphisms in patients with DR in the Indian population. Thedata suggest that the polymorphisms in the 5' UTR and promoter region ofVEGF could be regarded as a major genetic risk factor for DR.

[学科分类] 生物化学/生物物理