PSEN1 and Alzheimer disease: PS1 deficiency in presenilin 1 (PS1) knocked out human neural stem cells (NSCs) based on CRISPR/Cas9 system can also lead to autophagy damage of human neural stem cells by down-regulating ERK/CREB signal pathway, thus exacerbating the process of Alzheimer’s disease (Chong et al., 2018).