FcgammaRIIa, IIIa and IIIb gene polymorphisms in Behçet's disease: do they have any clinical implications?

Behçet's disease (BD) is a unique systemic vasculitis involving both arteries and veins of all sizes. Since Fcgamma receptors (FcgammaR) are important in mediating various immune effector functions, FcgammaR gene polymorphisms may affect the susceptibility to systemic inflammatory diseases such as BD. The aim of this study was to show the distribution of FcgammaRIIa, IIIa ve IIIb receptor gene polymorphisms in BD, and to investigate possible genotype-phenotype relationships. In this cross-sectional study, FcgammaRIIa (H/H131, H/R131, R/R131), IIIa (F/F158, F/V158, V/V158), and IIIb (NA1/NA1, NA1/NA2, and NA2/NA2) receptor gene polymorphisms were investigated in 216 unrelated Turkish BD patients (M/F: 130/86) and in 241 healthy subjects, using an allele-specific polymerase chain reaction. The FcgammaRIIa R/R131 (p=0.019) and FcgammaRIIIa F/F158 genotypes (p=0.001) were found to be significantly more frequent in BD compared with healthy controls, whereas the FcgammaRIIIb genotypes were not (p=0.108). Allele analysis showed that the FcgammaRIIIa 158 (p=0.001) and FcgammaRIIIb NA2 (p=0.016) alleles were more frequent in BD than in healthy controls. In BD patients the FcgammaRIIIa V/V158 genotype was significantly associated with the presence of arthritis (p=0.002) and with an earlier disease onset (p=0.008), while the FcgammaRIIIb NA2/NA2 genotype was significantly associated with disease severity (p=0.02), vascular involvement (p=0.014), and pathergy positivity (p=0.02). We found that the genotype frequencies and allelic distributions of the FcgammaRIIa, FcgammaRIIIa and FcgammaRIIIb gene polymorphisms were significantly different between BD patients and healthy controls. In addition, certain FcgammaRIIIa and FcgammaRIIIb gene polymorphisms appear to be associated with an early disease onset, disease severity, the presence of arthritis, and vascular involvement in BD.