FMR1 and schizophrenia: Previous studies9,14,23 have shown that schizophrenia patients have enriched de novo mutations in genes belonging to the postsynaptic density at glutamatergic synapses, such as components of the PSD complex, N-methyl-D-aspartic acid (NMDA) receptor signaling complex, ARC interactors, and the FMRP complex.