In validating the role of p25/Cdk5 in tauopathy, the authors derived iPSCs from frontotemporal dementia patient with Tau P301L mutation, generated P301L:Deltap35KI isogenic iPSC lines using CRISPR/Cas9 genome editing, and further created cerebral organoids from the isogenic iPSCs. The gene discussed is CDK5; the disease is tauopathy.