title: Aggressive periodontitis is likely influenced by a few small effect genes.
abstract: OBJECTIVE
  To evaluate the inheritance mode of aggressive periodontitis in a collection of families with a similar geographic origin.
  
  
  METHODS
  Segregation analysis was performed in pedigree data from 74 families by the use of the SEGREG program of SAGE v.5.4.2. Homogeneous no transmission, homogeneous Mendelian transmission, homogeneous general transmission, semi-general transmission and heterogeneous general transmission models were tested assuming the prevalence of aggressive periodontitis as 1% and no deviations from Hardy-Weinberg equilibrium. The parameters of the model were estimated by the method of maximum likelihood, which provides the overall ln (likelihood), -2ln and the AIC (Akaike's score) for each model. The likelihood ratio test (LRT) was used to compare each model against a fully general model (p>0.05).
  
  
  RESULTS
  The most parsimonious mode of inheritance was the semi-general transmission model that allows the heterozygote transmission probability to vary.
  
  
  CONCLUSIONS
  This result provides strong support for the hypothesis that genetic factors play a role in aggressive periodontitis and that a few loci, each with relatively small effects, contribute to aggressive periodontitis, with or without interaction with environmental factors.
authors.affiliation: Department of Periodontology, Rio de Janeiro State University, Rio de Janeiro, Brazil.
authors.forename: Flavia M
authors.initials: FM
authors.lastname: de Carvalho
authors.forename: Eduardo M B
authors.initials: EM
authors.lastname: Tinoco
authors.forename: Manika
authors.initials: M
authors.lastname: Govil
authors.forename: Mary L
authors.initials: ML
authors.lastname: Marazita
authors.forename: Alexandre R
authors.initials: AR
authors.lastname: Vieira
mesh_terms: D010520:Aggressive Periodontitis / Q000235:genetics*; D000483:Alleles; D001938:Brazil; D020090:Chromosome Segregation / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D018740:Genetic Heterogeneity; D020022:Genetic Predisposition to Disease / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008957:Models, Genetic; D010375:Pedigree; D010641:Phenotype