APP and Alzheimer disease: The Hexb-/- Sandhoff mouse model (Sango et al., 1995) and other mouse models of neurodegenerative LSDs share other features with AD, such as accumulation of amyloid precursor protein (APP) C-terminal fragments, Aβ, and phosphorylated tau in the brain (Annunziata et al., 2013, Beard et al., 2017, Boland et al., 2010, Jin et al., 2004, Keilani et al., 2012, Ohmi et al., 2011, Xu et al., 2014).