Candidate gene association study for diabetic retinopathy in Chinese patients with type 2 diabetes

PURPOSE: To investigate whether variants in a set of eight candidate genes are associated with diabetic retinopathy (DR) in a cohort of Chinese patients with type 2 diabetes mellitus (T2DM). METHODS: Case-control study. Patients with T2DM were recruited from the Desheng community in urban Beijing and assigned into a DR group or diabetic without retinopathy (DWR) group, based on the duration of diabetes and grading of fundus images. Twenty-six single-nucleotide polymorphisms (SNPs) within eight candidate genes, including PPARγ, vascular endothelial growth factor (VEGF) and its receptor kinase insert domain receptor (KDR), erythropoietin, aldose reductase, protein kinase C-β, angiotensin-converting enzyme, and intercellular adhesion molecule 1, were analyzed using the MassARRAY genotyping system. RESULTS: A total of 500 patients with T2DM (216 with DR and 284 with DWR) were enrolled in the study. Significant associations of DR were noted with genotypes of four SNPs—rs699947 (p<0.001), rs833061 (p=0.001), rs13207351 (p<0.001), and rs2146323 (p=0.006)—in the VEGF gene and one variant, rs2071559, in the KDR gene (p=0.034). After adjustment for covariates, significant association of DR remained with the homozygous genotype of the minor allele for the SNPs rs699947 (odds ratio [OR] = 3.54, 95% confidence interval [CI]: 1.12–11.19), rs833061 (OR = 3.72, 95% CI: 1.17–11.85), rs13207351 (OR = 3.76, 95% CI: 1.21–11.71), and rs2146323 (OR = 2.8, 95% CI: 1.46–5.37) in the VEGF gene as well as the SNP rs2071559 (OR = 1.62, 95% CI: 1.08–2.41) in the KDR gene. However, only rs699947 and rs13207351 in the VEGF gene remained statistically significant after Bonferroni correction. No associations were found in other genes tested. CONCLUSIONS: These data expanded previous observations on the association of DR with variants in the VEGF gene in Chinese patients with T2DM. Moreover, a possible association between DR and KDR polymorphisms is suggested.