GLUL and Rett syndrome: Other examples are Rett syndrome, in which disruptions of developmental support functions of astrocytes seem to contribute to dendritic and synaptic pathology (Lioy et al., 2011), and epilepsy syndromes caused by mutations in genes required for the homeostatic modulation of synaptic signaling by astrocytes, such as the glutamate transporter SLC1A2 (GLT‐1) or the glutamate‐metabolizing enzyme glutamine synthetase (GLUL) (Eid et al., 2019; Epi, 2016).