Another study has generated cerebral organoids using iPSCs derived from healthy individuals and compared these to organoids generated using iPSCs derived from patients with Alzheimer's disease (AD), finding an acceleration in SG formation in the AD patient-derived organoids, especially when the strongest genetic risk factor for AD, the APOE4 allele, was present (Zhao et al., 2020). The gene discussed is APOE; the disease is early-onset autosomal dominant Alzheimer disease.