GRIN2B and schizophrenia: It has also been demonstrated that the level of an ionotropic N-methyl-D-aspartate 2B subunit (GRIN2B) of the glutamate receptor tends to increase after subchronic administration of clozapine, suggesting that GRIN2B may play an active role in the pathogenesis of schizophrenia and the function of clozapine medication [16].