GRIN2B and Non-syndromic cerebral malformation due to abnormal neuronal migration: In another study on the subunit composition of the NMDA receptors performed in patients with malformations of cortical development, tissue from focal cortical dysplasia showed increased GluN2B subunit and tissue from periventricular nodular heterotopia showed a reduction of GluN1, GluN2A, and GluN2B [16].