Notably, astrocytes are directly involved in the synaptic abnormalities observed in both FXS mouse model and patients: the selective loss of FMRP in astrocytes leads to abnormal dendritic growth and aberrant synapse formation in developing WT neurons [91], whereas WT astrocytes efficiently normalize neuronal alterations in co-culture systems [92]. This evidence concerns the gene FMR1 and fragile X syndrome.