Aggressive periodontitis is likely influenced by a few small effect genes.
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.
de Carvalho
Flavia M
FM
Department of Periodontology, Rio de Janeiro State University, Rio de Janeiro, Brazil.
Tinoco
Eduardo M B
EM
Govil
Manika
M
Marazita
Mary L
ML
Vieira
Alexandre R
AR
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