With the purpose of modeling hippocampal pathology present in AD using a human-derived system, Pomeshchik and colleagues, using specific patterning compounds, recently described the generation of hippocampal spheroids from fAD patients with rare mutations in the APP (homozygous p.V717I) and PSEN1 (p.R278K) genes, which were able to engraft when injected into the hippocampus of RAG−/− mice. The gene discussed is APP; the disease is Alzheimer disease.