APP and Alzheimer disease: It has also been reported that APP mutation causes accumulation of APP C-terminal fragments (Tesco et al., 2005, p.181; Wiley et al., 2005, p. 205; Xu et al., 2016a) and that the production of APP C-terminal fragment by β-secretase increases in the brain of patients with sporadic AD (Pera et al., 2013).