APP and early-onset autosomal dominant Alzheimer disease: MIR9-2 is directed at two of the most important proteins in the etiopathogenesis of Alzheimer’s disease: the amyloid-beta precursor protein (APP), which transports the amyloid-β peptide that precipitates in amyloid plaques, and β-Site APP cleaving enzyme 1 (BACE1), which cleaves the APP to originate amyloid beta.