FCGR2A and Parkinson disease: There is indirect evidence for the importance of Fcγ receptors in PD: in postmortem human brain, PD is associated with increased binding of IgG to DA neurons in SN and elevated levels of FcγR on microglia [15]; FcγRI-dependent microglial responses to IgG from PD patients have been demonstrated in vitro [16]; and loss of DA neurons is observed in the SN of rodents following injection of IgG purified from the sera of PD patients, a process which is also FcγR dependent [17,18].