We hypothesised that synaptic protein levels could also be changed in primary psychiatric disorders and, indeed, compared with controls, attenuated expression levels, of for example, neurexin-3 (NRXN3), contactin-associated protein-like 4 (CNTNAP4) and glutamate ionotropic receptor AMPA type subunit 4 (GRIA4) were detected applying a proteomic approach.6 Here, GRIA4 is linked to psychiatric disorder.