Microglial cells greatly contribute to brain development: they assist in properly wiring excitatory and inhibitory circuits, they can affect neuronal maturation in neurogenic niches and they work in unison with other glial cells to maintain homeostasis in the ever-changing developing brain.36,37 These cells are thus believed to be involved in the pathogenesis of many neurodevelopmental disorders, including Rett syndrome.38 In fact, morphological abnormalities in microglia have been identified in MeCP2-null mice.16 Here, MECP2 is linked to Rett syndrome.