GRM5 and fragile X syndrome: Strikingly, the top genes related to synapses and neuronal projections that are downregulated are also FMRP bound (S7A Fig): Vamp2, which encodes a key component of AMPA receptor subunit vesicle trafficking [60]; Camk2b and Camkk2, which are both involved in the formation of dendritic spines [61]; and Grm5, which encodes the mGluR5 receptor, notably one of the main proposed therapeutic targets for FXS [62].