FcγRIIa and FcγRIIIa polymorphisms in childhood primary immune thrombocytopenia: implications for disease pathogenesis and outcome.

Primary immune thrombocytopenia (ITP) is the commonest acquired cause of bleeding in childhood. The aim of the present study was to evaluate the role of FcγRIIa and FcγRIIIa polymorphisms in the pathogenesis and therapeutic result of childhood ITP. The genotypic frequencies for two Fcγ receptor single-nucleotide polymorphisms, FcγRIIa-131 arginine (R) versus histidine (H) and FcγRIIIa-158 valine (V) versus phenylalanine (F) were examined in 53 children diagnosed with ITP. The genotype frequencies were compared with those of 45 healthy controls. The association between the above frequencies and disease natural course as well as therapeutic result following intravenous immunoglobulin (IVIG) administration was investigated. FcγRIIIa-158V was significantly overrepresented in children with ITP versus controls (P = 0.029), whereas no statistically significant difference was noted in FcγRIIa polymorphism distribution. No statistically significant difference was noted in the above genotype frequencies' distribution between children with newly diagnosed and chronic ITP, as well as with regards to the therapeutic result following IVIG administration. High-affinity FcγRIIIa variant (158 V) is possibly implicated in disease susceptibility, but neither of the two Fcγ receptor single-nucleotide polymorphisms seem to have any impact on chronicity or therapeutic effect of IVIG.