DKK1 and Alzheimer disease: DKK2 may thus behave similarly to DKK1, a negative regulator of canonical Wnt/β-catenin and noncanonical Wnt/PCP signaling with known synapse destabilizing properties (Purro et al., 2012; Galli et al., 2014; Killick et al., 2014; Marzo et al., 2016; Elliott et al., 2018; Sellers et al., 2018; also, for review, see Aghaizu et al., 2020), likely also in the human AD brain (Caricasole et al., 2004).