title: Complete physical mapping of IL6 reveals a new marker associated with chronic periodontitis.
abstract: OBJECTIVE
  Interleukin-6 (IL-6) is a powerful stimulator of osteoclast differentiation and bone resorption. Production of IL-6 is modulated by polymorphisms, and higher levels of this cytokine are found locally in patients with chronic periodontitis. In this study we performed a modern approach - Complete physical mapping of the IL6 gene - to identify the polymorphisms associated with chronic periodontitis in a southern Brazilian population sample.
  
  
  METHODS
  One-hundred and nine individuals of both genders (mean age: 41.5 ± 8.5 years) were divided into a study group (56 participants with periodontitis) and a control group (53 individuals without periodontitis). After collection and purification of DNA, nine tag single nucleotide polymorphisms (SNPs; rs1524107, rs2069835, rs2069837, rs2069838, rs2069840, rs2069842, rs2069843, rs2069845 and rs2069849) covering the entire gene were selected according to the information available on the International HapMap Project website and evaluated using real-time PCR.
  
  
  RESULTS
  Differences in the distribution of the following parameters were statistically significant between study and control groups: number of teeth (p = 0.030); probing depth (p < 0.001); clinical attachment level (p < 0.001); gingival index (p < 0.001); plaque index (p = 0.003); calculus index (p < 0.001); and dental mobility (p < 0.001). It was found that marker rs2069837 (located in intron 2 of IL6) under G dominant was associated with protection against chronic periodontitis in a Brazilian population in the presence of clinical variables, such as visible plaque, dentist visit frequency and dental floss use, and was suggested for the first time as a marker of susceptibility to chronic periodontitis.
  
  
  CONCLUSIONS
  Complete physical mapping of IL6 (using tag SNPs) was carried out for the first time, unveiling allele G of polymorphism rs2069837 (located in the second intron of IL6) as a suggestive marker of protection against chronic periodontitis in a Brazilian population.
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: S B
authors.initials: SB
authors.lastname: Farhat
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: C M
authors.initials: CM
authors.lastname: de Souza
authors.affiliation: School of Medicine, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: A P R
authors.initials: AP
authors.lastname: Braosi
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: V A
authors.initials: VA
authors.lastname: Tramontina
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: V
authors.initials: V
authors.lastname: Papalexiou
authors.affiliation: School of Medicine, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Olandoski
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: M T
authors.initials: MT
authors.lastname: Mira
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: S M
authors.initials: SM
authors.lastname: Luczyszyn
authors.affiliation: School of Health and Biosciences, Pontifícia Universidade Católica do Paraná, Curitiba, Brazil.
authors.forename: P C
authors.initials: PC
authors.lastname: Trevilatto
mesh_terms: D000328:Adult; D001938:Brazil; D016022:Case-Control Studies; D055113:Chronic Periodontitis / Q000235:genetics*; D003774:Dental Plaque Index; D005260:Female; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics* / Q000502:physiology; D008297:Male; D010512:Periodontal Index; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D005819:Genetic Markers; C508600:IL6 protein, human; D015850:Interleukin-6
keywords: cytokine; gene polymorphism; periodontal disease