Similar to EGR1, FOS is an IEG with well‐established roles in neuronal activity and brain development.[24] Dysregulation of both EGR1 and FOS has been reported in MED23‐deficient ESCs and NDD patients with MED23 or MED12 pathogenic variants.[25, 26, 27, 28]. The gene discussed is EGR1; the disease is Neurodevelopmental delay.