As discussed previously, the APOE gene was upregulated in disease-associated microglia (DAM) phenotypes [114], and one study found that in human induced pluripotent stem cells (iPSCs), going from the APOE3 allele to the APOE4 allele converted the microglial phenotype to DAM [128], which looked similar to the transcriptomic profile observed in the microglia of a human AD brain [129]. This evidence concerns the gene APOE and Alzheimer disease.