title: The composite interleukin-1 genotype in South Africa.
abstract: OBJECTIVE
  The objective of this study was to evaluate the association between the interleukin-1 composite gene polymorphism and the severity of periodontal disease in the Xhosa population of South Africa.
  
  
  BACKGROUND
  Periodontitis is a bacterially-induced chronic inflammatory disease that destroys the tooth supporting tissues. A specific pattern of interleukin-1 polymorphisms (known as the composite IL-1 genotype) has been found to influence the severity of chronic periodontitis in some ethnic groups.
  
  
  METHODS
  Ninety-nine subjects, 35-60 years of age, of Xhosa descent, who were non-smokers and free of systemic disease, were enrolled in a case-control study depending on their periodontal status (healthy to mild vs. moderate to severe disease). A buccal smear was obtained from each subject; the DNA was isolated then amplified using the polymerase chain reaction (PCR). Allele identification was either by real-time PCR or by size fractionation following restriction digestion and separation on a polyacrylamide gel.
  
  
  RESULTS
  The prevalence of the composite genotype was only 6% in the 99 subjects of the study population, which occurred more frequently in "cases" (8.2%) than in "controls" (4%). The frequency of IL-1A +4845 allele 2 genotype was 47% in cases and 22% in controls (p = 0.009), and that for IL-1B +3954 was 14.3% in cases and 20% in controls (p = 0.595).
  
  
  CONCLUSIONS
  This study demonstrated that the IL-1 composite polymorphism occurred among only few subjects in the Xhosa population of South Africa, and so was not significantly associated with the severity of chronic periodontitis in this population.
authors.affiliation: Department of Oral Medicine and Periodontology, University of the Western Cape, South Africa. tareqaman1@yahoo.com
authors.forename: T A
authors.initials: TA
authors.lastname: Saleh
authors.forename: L
authors.initials: L
authors.lastname: Stephen
authors.forename: M
authors.initials: M
authors.lastname: Kotze
authors.forename: A
authors.initials: A
authors.lastname: Pretorius
mesh_terms: D000328:Adult; D000483:Alleles; D044383:Black People / Q000235:genetics; D016022:Case-Control Studies; D055113:Chronic Periodontitis / Q000235:genetics* / Q000276:immunology; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007375:Interleukin-1 / Q000235:genetics*; D053582:Interleukin-1alpha / Q000235:genetics; D053583:Interleukin-1beta / Q000235:genetics; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D013019:South Africa
chemical_list: D007375:Interleukin-1; D053582:Interleukin-1alpha; D053583:Interleukin-1beta