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

Objective. Behcet's disease (BD) is a unique systemic vasculitis involving both arteries and veins of all sizes. Since Fcγ receptors (FcγR) are important in mediating various immune effector functions, FcyR gene polymorphisms may affect the susceptibility to systemic inflammatory diseases such as BD. The aim of this study was to show the distribution of FcγRIΙa, IΙΙa ve Illb receptor gene polymorphisms in BD, and to investigate possible genotype-phenotype relationships. Methods. In this cross-sectional study, FcyRIIa (H/H131, H/R131, R/R131), IΙΙa (F/F158, F/V158, V/V158) and IIIb (NA1/NA1, NA1/NA2, 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. Results. The FcγRIIa R/R131 (p=0.019) and FcγRIIΙa F/F158 genotypes (p=0.001) were found to be significantly more frequent in BD compared with healthy controls, whereas the FcγRΙΙΙb genotypes were not (p=0.108). Allele analysis showed that the FcγRIIIa F158 (p=0.001) and FcγRIIIb NA2 (p=0.016) alleles were more frequent in BD than in healthy controls. In BD patients the FcyRIIIa 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 FcγRΙΙΙb NA2/NA2 genotype was significantly associated with disease severity (p=0.02), vascular involvement (p=0.014), and pathergy positivity (p=0.02). Conclusion. We found that the genotype frequencies and allelic distributions of the FcyRIIa, FcyRIIIa and FcγRIIIb gene polymorphisms were significantly different between BD patients and healthy controls. In addition, certain FcyRIIIa and FcyRIIIb gene polymorphisms appear to be associated with an early disease onset, disease severity, the presence of arthritis, and vascular involvement in BD.