Fcγ receptor genes as risk markers for localized aggressive periodontitis in African-Americans

Background: Receptors for the Fc fragment of immunoglobulin G (FcgammaRs) play a crucial role in host defense against bacterial infection by linking humoral and cell-mediated immune responses. Allelic variants of certain FcgammaRs have been shown to differ relative to their biologic activity. Thus, genes encoding allotypes with diminished activity have been suggested as potential risk factors for infectious diseases. The goal of this study was to determine whether specific FcgammaRIIa, FcgammaRIIIa, and FcgammaRIIIb alleles and/or genotypes could be used to predict susceptibility to localized aggressive periodontitis (LAgP) in an African-American population. Methods: Whole blood or saliva was obtained from 48 LAgP and 67 periodontally-healthy African-American subjects. DNA was prepared from each sample. FcgammaRIIa and FcgammaRIIIa genotyping was analyzed by polymerase chain reaction (PCR) amplification of DNA with allele-specific primers followed by allele-specific restriction digestion of the products. FcgammaRIIIb genotyping was done by allele-specific PCR. Results: There was a statistically significant over-representation of the FcgammaRIIIb-NA2 allele in LAgP patients compared to controls (P=0.024). Relative to the FcgammaRIIIb-NA1/NA2 and homozygous NA1/NA1 genotypes, the prevalence of the FcgammaRIIIb NA2/NA2 genotype was higher in the LAgP group relative to the control population. Individuals expressing this genotype appeared at greater risk for developing LAgP (odds ratio 2.271, 95% confidence interval: 1.005 to 5.132). There were no significant differences in the distribution of the FcgammaRIIa H/R or FcgammaRIIIa-158 F/V genotypes nor their allelic frequencies between the LAgP patients and controls. Conclusions: These data suggest that the FcgammaRIIIb NA2 allele and/or NA2/NA2 genotype may represent risk markers for susceptibility to LAgP in African-Americans.