FCGR2A and Thrombocytopenia: Unexpectedly, we and others have identified a novel mechanism of Fc-independent thrombocytopenia, in which antibodies against GPIbα, but not those against GPIIbIIIa, can induce thrombocytopenia via their F(ab)2 (Fc independent) and in FcγR−/− mice11, 12.