This is consistent with the increased reactive/amoeboid cell population reported with the 2D assessment in AD, the cognitive decline associated with phagocytic microglia (CD68, MSR-A, HLA-DR, CD64)21 and the sequence of events recently proposed to explain AD neuropathogenesis in which the microglial reaction to Aβ is a key step31. This evidence concerns the gene FCGR1A and Alzheimer disease.