Furthermore, when APOE knock‐in mice were crossed to a tauopathy model (P301S), CD68‐positive microglial burdens in the hippocampus and entorhinal/piriform cortex were markedly increased in APOE4 mice compared APOE3 and APOE knock‐out mice in a tau pathology mediated manner 9. The gene discussed is MAPT; the disease is tauopathy.