APP and early-onset autosomal dominant Alzheimer disease: The family of amyloid precursor protein (APP)-like proteins (APLP1 and APLP2) has been the focus of intensive research in recent decades owing to the involvement of APP and its cleavage product Aβ in the pathology of Alzheimer’s disease (Dawkins & Small, 2014 ▶; Muller & Zheng, 2012 ▶; Blennow et al., 2006 ▶).