Here, we investigate whether a novel cellular model of DS that carry three copies of 148 mouse genes that are homologous with Hsa21 genes, including App, Synj1, Itsn1, Rcan1, Mir155, Dyrk1A and Bace2, can be used to study APP/amyloid-β and endosomal biology. Here, SYNJ1 is linked to Dravet syndrome.