Engineered iPSCs-derived brain organoids were established to model microcephaly by RNA interference of reprogramming factors (Lancaster et al. 2013), autism by overexpression of the transcription factor FOXG1 (forkhead box G1) (Mariani et al. 2015), macrocephaly by deletion of PTEN (Li et al. 2017), Timothy syndrome by introducing mutations in the CaV1.2 calcium channel-interneurons (Birey et al. 2017) and Aicardi-Goutières syndrome by introducing inactivation mutation of TREX-1 (Thomas et al. 2017). The gene discussed is FOXG1; the disease is Timothy syndrome.