The association between toll-like receptor 4 polymorphisms and diabetic retinopathy in Chinese patients with type 2 diabetes

Purpose: Diabetic retinopathy (DR) is one of the secondary microvascular complications of type 2 diabetes mellitus. Persistent inflammation and impaired neovascularisation may be important contributors to the development of DR. A recent study showed that toll-like receptor 4 (TLR4) polymorphisms were associated with DR. The present study was designed to determine whether single-nucleotide polymorphisms (SNPs) in the TLR4 gene were associated with DR in a Chinese Han population.

Materials and methods: Three SNPs (rs10759931, rs1927911 and rs1927914) in the TLR4 gene were chosen as candidate SNPs. Genomic DNA from type 2 diabetes patients and healthy controls were genotyped for the above-mentioned genetic variations through the use of PCR restriction fragment length polymorphism assay. Data were analysed by χ(2) analysis.

Results: The results showed that the three analysed polymorphisms in the TLR4 gene were in Hardy-Weinberg equilibrium, both in the patients and in the controls. In the type 2 diabetes group, a significantly higher frequency of the C allele of rs1927914 was observed in patients with type 2 diabetes than that in controls. The result showed that the frequencies of the TT genotype and the T allele of rs1927914 were significantly decreased in patients with type 2 diabetes. Significantly increased frequencies of the CC genotype and the C allele of rs1927911 were observed in patients with type 2 diabetes. In the DR group, the C allele of rs1927914 was significantly increased in the DR group compared with that of the control. The frequencies of the CC genotype and the C allele of rs1927911 tended to be higher in patients with DR than in the healthy controls. However, no difference was found when the Bonferroni correction was applied. No difference was detected between patients and controls with regard to all haplotypes.

Conclusions: This study suggested that rs1927914 and rs1927911 were associated with type 2 diabetes mellitus and that rs1927914 was associated with susceptibility to DR in a Han Chinese population.