Investigation of association between TLR9 gene polymorphisms and VKH in Japanese patients.

Purpose: Vogt-Koyanagi-Harada (VKH) disease is an autoimmune disorder affecting melanocytes in the skin, eyes, inner ear, and meninges. The Epstein-Barr virus and cytomegalovirus (CMV) antigen have been hypothesized as possible triggering factors for the disease. Toll-like receptors (TLRs) play an important role in the induction of defense mechanisms of the innate and adaptive immune responses to microbial pathogens. Among TLRs, TLR9 recognizes unmethylated 2'-deoxyribo (cytidine-phosphate guanosine)(CpG) DNA motifs that are frequently present in viruses and plays a central role in the host defense against viral infection. The aim of this study was to investigate whether TLR9 polymorphisms were associated with VKH in a Japanese population.

Methods: Ninety-four Japanese patients diagnosed with VKH and 125 healthy control subjects were recruited. Five single-nucleotide polymorphisms (SNPs: rs187084, rs5743836, rs352139, rs352140, rs5743845) in the TLR9 gene were genotyped, and allelic and phenotypic diversity was assessed between cases and control subjects.

Results: Strong linkage disequilibrium was observed among three SNPs (D' > 0.99), which were located in one haplotype block. Two SNPs (rs5743836 and rs5743845) were monopolymorphic in both cases and controls. No statistically significant association was observed for any of the SNPs between cases and controls.

Conclusion: Three SNPs in the TLR9 gene were not significantly associated with susceptibility to VKH.