APP and early-onset autosomal dominant Alzheimer disease: It is intriguing that Alzheimer’s disease (AD) and a rare inherited lipid storage disorder Niemann-Pick type C (NPC) share several pathological features, including a dysfunctional endolysosomal system, enhanced amyloidogenic APP processing (resulting in accumulation of the C-terminal APP fragments (CTFβ/C99) and Aβ peptides), tau pathology, apolipoprotein E ε4 risk factor, activation of astrocytes and microglia (neuroinflammation), synaptic dysfunction and neurodegeneration [32,33].