After 1 month of co-culture, APOE4 allele exhibited more extracellular Aβ aggregates than those co-cultured with APOE3 microglia-like cells, showing that APOE4 negatively impacts microglial function with a poor ability to clear extracellular Aβ from AD brains, and possibly influencing the brain inflammatory profile (Lin et al., 2018). Here, APOE is linked to Alzheimer disease.