MECP2 and Rett syndrome: PCDH19 epilepsy is a dramatic example where mismatched synaptic interactions have deleterious consequences [96], but the possibility of non-cell-autonomous effects in other disorders, such as the observation in models of RTT that even wild-type neurons can show synaptic deficits if the synapse is interacting with a MeCP2 null astrocyte [54], suggest that these specific interactions could be making unappreciated contributions to the pathophysiology of similar disorders.