Additionally, different from the condensed AT8 signals after AD brain extract exposure, weak and diffuse axonal AT8+ signals were observed in organoids at 2 weeks post-exposure to the vehicle and healthy control brain extracts (Fig. 3A, S7, and S8), aligning with prior studies that identified transient phosphorylated tau in neurons during development [53, 61]. The gene discussed is MAPT; the disease is Alzheimer disease.