APP and early-onset autosomal dominant Alzheimer disease: Alzheimer's disease (AD), a debilitating neurodegenerative condition, is characterized by progressive cognitive decline brought aboutby the deposition of amyloid beta (Aβ) plaques in the brain initiates downstream neuronal dysfunction and death in AD pathogenesis.The β-secretase (BACE-1) enzyme plays a crucial role in generating Aβ from amyloid precursor protein (APP).