A caveat worth mentioning in relation to the lack of DKK2 upregulation is the fact that human microglia at AD end stage (Braak & Braak stage 5–6) were chronically exposed to disease for much longer periods than their mouse counterparts and chronic adaptations in microglia gene expression signatures as well as microglial numbers may have masked potential earlier changes (we note that our pathologic aging samples at Braak & Braak stage 3–4 also lacked DKK2 upregulation). Here, DKK2 is linked to Alzheimer disease.