Of these genes, ApoE, TREM2, and CD33 have been identified as key genes involved in the intermediate state of disease-associated microglia (DAM, also referred to as microglial neurodegenerative phenotype) by most recent single-cell RNA sequencing studies of microglia from AD-transgenic (Tg) mice (Keren-Shaul et al., 2017; Krasemann et al., 2017). This evidence concerns the gene CD33 and Alzheimer disease.