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Abstract
Immune thrombocytopenic purpura (ITP) is a bleeding disorder of infants, children, and adults. The majority of affected children have the acute form of ITP, defined by a duration of thrombocytopenia (< 150 x 109/L) of < 6 months. Previous studies have shown that Fc gamma receptors (FcγRs) play crucial roles in platelet phagocytosis, antibodies bound to platelets have their Fc portion exposed which allows binding to monocytes/macrophages that express Fc receptors for IgG (FcγRs).
The FcγRIIIa Valine (V) has increased affinity for three separate IgG subclasses when compared with the FcγRIIIa Phenylalanine (F).
The aim of the present study is to assess the frequency of occurrence of the high affinity allelic variant FcγRIIIa – 158V in Egyptian children with ITP in comparison to normal individuals.
Determination of FcγRIIIa genotype was performed for 30 ITP patients and 10 healthy control subjects by nested PCR followed by RFLP analysis.
In our study, the allelic frequency of FcγRIIIa – 158V was (76.6%) among ITP patient group in contrast to (20%) among the control group. These results suggest that FcγRIIIa – 158V/F polymorphism contributes to the pathogenesis of childhood ITP by increased clearance of antibody- sensitized platelets by the high affinity FcγRIIIa – 158V allelic variant.