FCGR1A and Alzheimer disease: However, the morphological changes noticed in our study are relevant to the increased microglial activation that we reported in AD using CD68 (phagocytic activity), macrophage scavenger receptor (MSR)-A (scavenging activity), and CD64 and CD16 (Fcγ receptor I and III respectively, and central effectors of immunoglobulins mediated immune response)20–22.