APOE and Alzheimer disease: Lin et al. (2018) used the CRISPR/Cas9 system in iPSC-derived organoids to convert APOE4 to APOE3, which alleviated multiple AD-related pathologies. Hudry et al. (2013) introduced APOE2 into AD model mice using AAV, reducing the accumulation of Aβ deposits and suggesting that gene transfer to reduce APOE4 or increase APOE2 could help inhibit the progression of AD.