APP and early-onset autosomal dominant Alzheimer disease: Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by the deposition of amyloid beta (Aβ) plaques and the aggregation of neurofibrillary tangles (NFTs) caused by the hyperphosphorylated tau protein, and involves mutations in amyloid precursor protein (APP), presenilin 1 (PSEN1), presenilin 2 (PSEN2), and apolipoprotein E (APOE) (Bekris et al., 2010; Iqbal et al., 2010; Poon et al., 2020).