Polymorphisms in the von Willebrand factor gene are not associated with proliferative retinopathy in non-insulin-dependent diabetes mellitus

Von Willebrand factor, a multimeric glycoprotein synthesized mainly by endothelial cells, is involved in platelet adhesion and aggregation and has an important role in the process of angiogenesis. Increased levels of von Willebrand factor, reflecting activation or damage of endothelial cells, have been described in association with proliferative diabetic retinopathy (PDR). We investigated the relationships of two polymorphisms (-1793G/C and Thr789Ala) in the von Willebrand factor gene with PDR. Genotypes were detected by polymerase chain reactions with subsequent restrictions with specific endonucleases. Allele frequencies were determined in an association study (n = 371) comprising three groups of subjects (diabetics with and without retinopathy and nondiabetics). Allele frequencies of the -1793G/C and Thr789Ala did not differ between the non-insulin-dependent diabetes mellitus (NIDDM) + PDR and the NIDDM non-PDR groups (p > 0.05). However, a statistically significant difference in allele and genotype frequencies of the -1793G/C was proved between all NIDDM versus nondiabetic subjects (p = 0.024 and 0.0065, respectively) with allele G and genotype GG being significantly more frequent in the NIDDM group. Calculated odds ratio for the GG genotype was 1.20 (95% CI, 0.77-1.86). Although significantly higher plasma von Willebrand factor antigen levels in NIDDM patients with PDR have been described in several studies, our findings indicate that no association exists between the two polymorphisms and PDR. However, the -1793G/C polymorphism might affect the risk of NIDDM.