title: Interleukin-1 gene polymorphisms and chronic periodontitis in adult whites: a systematic review and meta-analysis.
abstract: BACKGROUND
  Interleukin-1 (IL-1) gene polymorphisms have been associated with increased levels of inflammatory mediators and several inflammatory diseases. Periodontitis is a bacterially induced chronic inflammatory disease that destroys the connective tissues and bone that support the teeth, affects substantial numbers of adults, and has been implicated as a contributing factor in systemic diseases. IL-1 gene polymorphisms, most prominently IL1A (-889), IL1A (+4845), and IL1B (+3954), have been associated with chronic periodontitis (CP) in whites. Since the first report, ≥125 studies have examined IL-1 gene variation in relation to periodontal disease. These studies have produced mixed findings in diverse periodontal phenotypes and in different ethnic groups. One previous meta-analysis has been published on this topic and supported an association between IL-1 genes and periodontitis, but considerable doubt remains about the patient populations in which the association may be of clinical relevance.
  
  
  METHODS
  A systematic review and meta-analysis was conducted in an attempt to clarify whether IL-1 gene variants were associated with well-defined clinical phenotypes of CP in white patients. Study inclusion criteria focused on the analytic framework originally proposed for the IL-1 genetic effect in which overexpression of inflammatory mediators is hypothesized to result in more severe periodontitis in response to a bacterial challenge.
  
  
  RESULTS
  Twenty-seven studies were included in the qualitative analysis. Nineteen studies yielded significant associations between carriage of the minor IL-1 alleles and periodontitis. The meta-analysis, based on 13 qualifying studies, found significant effects for the two individual gene variations (IL1A odds ratio [OR] = 1.48; IL1B OR = 1.54) and for a composite genotype that combines minor alleles at each locus (OR = 1.51). Statistically significant heterogeneity was found that could not be explained, but there was no indication of publication bias.
  
  
  CONCLUSIONS
  This review and meta-analysis show that IL1A and IL1B genetic variations are significant contributors to CP in whites.
authors.affiliation: Department of Oral Medicine Infection and Immunity, Harvard University School of Dental Medicine, Boston, MA. Nadeem.Karimbux@tufts.edu
authors.forename: Nadeem Y
authors.initials: NY
authors.lastname: Karimbux
authors.forename: Veeral M
authors.initials: VM
authors.lastname: Saraiya
authors.forename: Satheesh
authors.initials: S
authors.lastname: Elangovan
authors.forename: Veerasathpurush
authors.initials: V
authors.lastname: Allareddy
authors.forename: Taru
authors.initials: T
authors.lastname: Kinnunen
authors.forename: Kenneth S
authors.initials: KS
authors.lastname: Kornman
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Duff
mesh_terms: D000328:Adult; D055113:Chronic Periodontitis / Q000235:genetics*; D006801:Humans; D007375:Interleukin-1 / Q000235:genetics*; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D044465:White People / Q000235:genetics
chemical_list: D007375:Interleukin-1