BACE1 and early-onset autosomal dominant Alzheimer disease: The β-secretase BACE1, which initiates amyloid-β (Aβ) production, is a long-standing prime therapeutic target for Alzheimer's disease (AD) based on solid evidence that Aβ increase is the first event driving subsequent pathological changes and cognitive symptoms (Hanseeuw et al., 2019; Jack et al., 2019).