The second method is to use genetic tools, such as lentivirus vectors or CRISPR-Cas9 gene-editing system, to overexpress AD-related genes, such as APP, PS1/2, and apolipoprotein E3/E4 (APOE3/E4), in hPSC-derived cells [27,28,29]. Here, PSEN1 is linked to Alzheimer disease.