However, one large cohort of people almost certain to get AD are those with DS or trisomy 21 which is caused by three copies of HSA21 as opposed to the normal two, with AD causal gene, APP located on HSA21, hence three copies of APP leading to increased likelihood of AD pathology (Selkoe and Hardy, 2016; Herault et al., 2017). Here, APP is linked to Dravet syndrome.