title: Toll-like receptor 2 gene polymorphisms associated with aggressive periodontitis in Japanese.
abstract: OBJECTIVE
  Aggressive periodontitis is a rare and very severe periodontal disease of early onset, which is closely associated with Porphyromonas.gingivalis (P.g.) infection in the Japanese population. TLR2 encodes Toll-like receptor 2, which plays an important role in the protective response to P.g. infection. We investigated a possible association between TLR2 and aggressive periodontitis.
  
  
  METHODS
  Of 2,460 Japanese patients with periodontitis, 38 patients with aggressive periodontitis were enrolled in this study. These 38 aggressive periodontitis patients and 190 Japanese healthy controls were examined for an insertion/deletion (Ins/Del) polymorphism in exon 1, a polymorphism in intron 1 (rs7696323), and a synonymous polymorphism in exon 3 (rs3804100) in TLR2.
  
  
  RESULTS
  We found significant associations of resistance to aggressive periodontitis with the Ins allele (allele frequency in the patients versus controls, 0.540 vs. 0.676, OR=0.56, 95% confidence interval (CI); 0.34-0.92, p=0.022) and the T allele of rs3804100 (0.579 vs. 0.716, OR=0.55, 95% CI; 0.33-0.91, p=0.018), although the C allele of rs7696323 showed no significant association (0.733 vs. 0.829, OR=0.58). A permutation test of Ins/Del-rs7696323-rs3804100 haplotype revealed a significant association between Ins-C-T haplotype (0.252 vs. 0.479, p=0.0003) and resistance to aggressive periodontitis.
  
  
  CONCLUSIONS
  The TLR2 polymorphisms were suggested to confer protection against aggressive periodontitis in a Japanese population. The association should be replicated in other cohorts to further identify the responsible TLR polymorphism(s) involved in the pathogenesis of aggressive periodontitis.
authors.affiliation: Section of Periodontology, Department of Hard Tissue Engineering, Graduate School of Medical and Dental Science.
authors.forename: Marika
authors.initials: M
authors.lastname: Takahashi
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Chen
authors.forename: Kaoru
authors.initials: K
authors.lastname: Watanabe
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nakajima
authors.forename: Akinori
authors.initials: A
authors.lastname: Kimura
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Izumi