Agonists of the metabotropic group II receptors (mGluR2 and mGluR3) inhibit glutamate release in synapses of the glutamatergic hippocampal neurons of epilepsy patients and are potent anticonvulsants against motor and absence seizures (97), indicating that a shortage of metabotropic group II receptors may cause the generation of seizures in epilepsy patients. This evidence concerns the gene GRM3 and epilepsy.