Are vitamin D receptor gene rs731236, rs2228570 and NOS3 gene rs3138808 polymorphisms associated with diabetic...

Despite efforts to date, little is known about the genetic background of diabetic retinopathy (DR). Pathogenesis of DR involves processes like inflammation, proliferation and angiogenesis that vitamin D receptor (VDR) and endothelial nitric oxide (NOS3) genes are involved. Investigation of associations between VDR gene rs731236, rs2228570 and NOS3 gene rs3138808 polymorphisms and diabetic retinopathy was aimed.

260 participants were divided into three groups: controls (n = 83), non-proliferative diabetic retinopathy (NPDR) (n = 101) and proliferative diabetic retinopathy (PDR) (n = 46). PCR-RFLP assay was used for genotyping. Genotype and allele frequencies as well as basic characteristics were compared both between groups and intragroup.

Mean FPG (p = 0.003), mean HbA1c (%) (p = 0.007) and mean HbA1c (p = 0.003) were significantly different between groups. Mean FPG of NPDR patients in rs731236 polymorphism was significantly different between genotypes under additive model (p = 0.018). Under dominant model, mean FPG of NPDR patients in rs731236 was significantly different between TT and TC+CC genotypes (p = 0.009). Under dominant model regarding rs2228570, mean BUN level of homozygous wild-type genotype was significantly higher than that of polymorphic allele carriers of NPDR group (p = 0.022). Regarding rs2228570 polymorphism, plasma creatine level of polymorphic genotypes was significantly lower than that of wild type genotype in control group (p = 0.040). Allele and genotype frequencies among groups were not significantly different (p > 0.05). Binary regression analysis didn't indicate any significant influence on having DR (p > 0.05, all).

In the studied population, this study is the first to investigate and demonstrate that VDR gene polymorphisms rs731236 and rs2228570 and NOS3 gene polymorphism rs3138808 are not associated with diabetic retinopathy.