DKK1 and Alzheimer disease: Dkk1, which inhibits Wnt signaling by binding to the LRPs and preventing Wnts from forming a complex with Fz and LRPs (Zorn, 2001), is increased in brains of both familial/early-onset AD and sporadic/late-onset AD patients (De Ferrari and Moon, 2006; Boonen et al., 2009).