Distribution of FcγRIIa and FcγRIIIb genotypes in patients with generalized aggressive periodontitis

Background: Polymorphisms in Fc gamma R have been associated with different forms of periodontitis. This study determined the frequency of Fc gamma RIIa and Fc gamma RIIIb alleles/genotypes in patients with generalized aggressive periodontitis (GAgP). Methods: Thirty-one GAgP and 49 periodontally healthy Brazilian subjects participated in the study. Full-mouth periodontal examinations were carried out, and mouthwash samples were collected for human DNA isolation. Fc gamma R genotyping was performed by polymerase chain reaction and hybridization with allele-specific oligonucleotide probes. Significant differences between groups were sought by Mann-Whitney, X 2, and Fisher exact tests and configural frequency analysis. Results: Fc gamma RIIa-H131 (53.8%) and Fc gamma RIIIb-NA1 (75%) were the most prevalent alleles in this sample population. A significant overrepresentation of Fc gamma RIIIb-NA2 was observed in the GAgP group, whereas Fc gamma RIIIb-NA1 was detected more often in healthy individuals (odds ratio, 32.5; 95% confidence interval [CI], 10.6 to 99.8; P < 0.001). No significant differences in the distribution of the Fc gamma RIIa genotypes were observed between the groups. The prevalence of Fc gamma RIIIb-NA2/NA2 was higher in GAgP patients, whereas Fc gamma RIIIb-NA1/NA1 was predominant in the healthy group (x(2) = 45.1; P < 0.001). The combination of the genotypes Fc gamma RIIIb-NA2/NA2 plus Fc gamma RIIa-H/H131 was observed more frequently in GAgP subjects than expected from marginal frequencies (x(2) = 12.5; P < 0.001). Conclusions: The data suggest that the Fc gamma RIIIb-NA2 allele and/or Fc gamma RIIIb-NA2/NA2 genotype and the composite genotype Fc gamma RIIIb-NA2/NA2 plus Fc gamma RIIa-H/H131 may be associated with GAgP, whereas Fc gamma RIIIb-NA1 and/or Fc gamma RIIIb-NA1/NA1 may be related to periodontal health in this sample of the Brazilian population.