GRM5 and fragile X syndrome: An example of this is an upcoming trial re-examining the efficacy of the metabotropic glutamate receptor 5 (mGluR5) antagonist mavoglurant in FXS, which will introduce modifications such as the study of younger individuals, presumably more receptive to interventions targeting synaptic development, and the use of a cognitive intervention during the drug trial, aimed at enhancing drug effect on learning and consequently on synaptic plasticity.