Primary fibroblast cultures were established from dermal punch biopsies taken from individuals following informed consent and Institutional Review Board approval. To generate iPSCs, fibroblasts were transduced with MMLV vectors containing the complementary DNAs for OCT4, SOX2, KLF4, c-MYC and ± EGFP. IPSC-derived NPCs were differentiated for 3 weeks, neurons were purified by FACS, and amyloid-β, p-tau/total tau and aGSK-3β were measured on purified control and mutant neurons from multiple lines cultured in parallel for an additional 5 days by multi-spot electrochemiluminescence assays (Meso Scale Diagnostics). Early endosomes were analysed by confocal microscopy on purified neurons co-cultured with human astrocytes (Lonza) for 12 days. To ensure reproducible and consistent data, we found that it is important to differentiate and evaluate neurons from full sets of mutant and control iPSC lines together.