Toll-like receptor 4 polymorphisms in patients with Stargardt disease: A family study

Abstract

Purpose: Retinal pigment epithelial cells exhibit a propensity for apoptosis in Stargardt macular dystrophy (STGD). Previously, single-nucleotide polymorphisms (SNPs) in the toll-like receptor 4 (TLR4) gene have been related to apoptosis and inflammatory response. Therefore, this study was undertaken to investigate whether TLR4 SNPs are associated with STGD in a family-based study. Methods: Four blood-related Mexican patients with a clinical diagnosis of STGD (4 women) and 12 of their unaffected relatives were included in the study. A total of 109 subjects (40 men and 69 women; age, 63.28 ± 7.93 years) without macular affections, family history, or inherited macular dystrophies were used as controls. SNPs rs4986790, rs1927911, rs12377632, rs2149356, and rs11536889 of the TLR4 gene were genotyped using a Taqman â Allelic Discrimination Assay. Results: The frequency of the minor allele of rs4986790 (G) was significantly higher in STGD patients compared to control subjects (25% vs. 1%, p = 0.0012). The genotype carrying the minor allele of rs4986790 (AG) was more frequent in STGD patients (50%) compared with their relatives and unrelated control subjects (8 and 2.75%, respectively), with statistical significance (p = 0.0048). The allele and genotype frequencies of the remaining SNPs were not significant between STGD patients and control subjects (p > 0.5). Unaffected relatives of STGD patients showed allele and genotype frequencies similar to those observed in control subjects. Conclusion: Minor alleles of the SNPs rs4986790 (G) and genotypes carrying it (AG) were related to clinical STGD in one family. Interestingly, rs4986790 has been described as a promoter of apoptosis. Therefore, this TLR4 gene polymorphism should be considered as a marker in future studies.