The AD patient iNs exhibited well-developed and mature neuronal characteristics, but the number of TUJ1+/NeuN+ cells was slightly decreased in the AD patient iNs that expressed APOE ε4 at the amyloid-seeding stage, compared to the AD patient iNs without APOE ε4 expression, while no such difference was found when APOE ε4 was expressed at the amyloid progressive stage (Fig. 1f). This evidence concerns the gene APOE and Alzheimer disease.