APOE and Alzheimer disease: By immunophenotyping microglia in the frontal gyrus and correlating to APOE status in AD and control cases, markers of activation (CD68, Human Leucocyte Antigen‐DR isotype [HLA‐DR], CD64) were found to be significantly associated with APOE4 carriers while APOE2 carriers were associated with higher levels of more homoeostatic microglial markers (Iba1 and Macrophage Scavenger Receptor‐A; MSR‐A) and lower levels of the reactive ones 85.