Definition:

Immune thrombocytopenic purpura (ITP) is an acquired autoimmune disorder, and the most common cause of isolated thrombocytopenia in children. Destruction of autoantibody-sensitized platelets by Fc[gamma]R-bearing phagocytic cells in the reticuloendothelial system plays an important role. ITP is diagnosed clinically, based upon onset of thrombocytopenia in the absence of other hematologic abnormalities, or other causes of low platelets, and with a characteristic blood smear. While around 50% of typical childhood acute ITP is preceded by a viral or bacterial infection and commonly resolves within weeks to months without treatment, fewer adult cases are acute and self-resolving. Typical adult primary ITP is very similar clinically to chronic pediatric ITP. Intravenous immunoglobulin (IVIg) treatment and splenectomy (removal of the platelet-destructing organ) are effective treatment options. It has been reported that the activating FCGR2C-ORF genotype predisposes to ITP by altering the balance of activating and inhibitory Fc[gamma]R on immune cells.