Mutations around the β‐secretase cleavage site or additional copies of APP because of local genomic duplications or Down's syndrome increase the total production of Aβ (Alić et al. 2020; Chang et al. 2015; Israel et al. 2012; Kondo et al. 2013; Kwart et al. 2019; Moore et al. 2015; Raja et al. 2016; Shi, Kirwan, Smith, MacLean, et al., 2012). Here, APP is linked to Down syndrome.