Previous reports of Fyn’s multiple roles in the pathogenesis of Alzheimer’s disease suggest several unexplored aspects of this kinase during Parkinsonian neurodegeneration (Crews and Masliah; Haass and Mandelkow, 2010; Souter and Lee, 2010; Lee et al., 1998; Lee et al., 2004; Bhaskar et al., 2005; Derkinderen et al., 2005; Lee, 2005; Williamson et al., 2008; Hernandez et al., 2009). Here, FYN is linked to early-onset autosomal dominant Alzheimer disease.