Even though the mechanism of dendritic spine maturation is not fully elucidated, recent observations suggest that the proper pruning and maturation of synaptic spines (impaired in FXS) rely on the interplay between local dendritic BDNF mRNA translation and secretion, with FMRP playing a key role in the regulation of these local events [133]. The gene discussed is FMR1; the disease is fragile X syndrome.