title: Vitamin D Receptor Gene Polymorphism and Smoking in the Risk of Chronic Periodontitis.
abstract: Polymorphisms of the vitamin D receptor (VDR) gene have been implicated in susceptibility to infections and bone-related diseases. However, their relationship with periodontal disease remains unclear. This cross-sectional study investigates whether susceptibility to chronic periodontitis (CP) in a Thai population is associated with VDR polymorphisms.
  
  
  
  Genomic DNA was obtained from 1,460 participants, aged 39 to 66 years. Genotyping of VDR polymorphisms (FokI, BsmI, ApaI, and TaqI) was performed using real-time polymerase chain reaction. Participants were categorized into three groups: 1) no/mild; 2) moderate; and 3) severe CP. Multinomial logistic regression was used to determine degree of association between VDR polymorphisms and periodontal status adjusted for known confounders.
  
  
  
  The CC+CT genotypes of FokI polymorphism were associated with severe CP with an odds ratio (OR) of 1.9 (95% confidence interval [CI]: 1.3 to 2.8). Compared with genotype-negative (TT) non-smokers, positivity for the risk genotypes (CC+CT) alone and current smoking alone were associated with severe CP with ORs of 1.8 (95% CI: 1.1 to 3.2) and 2.5 (95% CI: 1.0 to 6.2), respectively. The combination of being genotype positive and smoking further increased the OR to 9.6 (95% CI: 4.5 to 20.4). This combined effect was 3.7 times (95% CI: 1.2 to 11.1) greater than expected from the sum of their individual effects, indicating a synergistic interaction. No significant association was observed between other polymorphisms and CP.
  
  
  
  FokI CC+CT genotypes were associated with increased susceptibility to severe CP, which was aggravated further when combined with smoking.
authors.affiliation: Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Soranun
authors.initials: S
authors.lastname: Chantarangsu
authors.affiliation: Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Thanyachai
authors.initials: T
authors.lastname: Sura
authors.affiliation: Department of Periodontology, Faculty of Dentistry, Chulalongkorn University.
authors.forename: Sanutm
authors.initials: S
authors.lastname: Mongkornkarn
authors.affiliation: Medical and Health Department, Health Division, Electricity Generating Authority of Thailand, Nonthaburi, Thailand.
authors.forename: Kobkiat
authors.initials: K
authors.lastname: Donsakul
authors.affiliation: Department of Microbiology, Faculty of Dentistry, Chulalongkorn University.
authors.forename: Kitti
authors.initials: K
authors.lastname: Torrungruang
mesh_terms: D000328:Adult; D000368:Aged; D055113:Chronic Periodontitis / Q000235:genetics*; D003430:Cross-Sectional Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D018167:Receptors, Calcitriol / Q000235:genetics*; D012306:Risk; D012907:Smoking
chemical_list: D018167:Receptors, Calcitriol; C579457:VDR protein, human
keywords: Chronic periodontitis; Thailand; polymorphism, genetic; receptors, calcitriol; smoking