Each GluN2 subtype—GluN2A, GluN2B, GluN2C, and GluN2D—contributes to synaptic transmission, plasticity, and excitability, and their diverse combinations and interactions with other receptor subunits may influence pathological mechanisms underlying conditions such as epilepsy, ASD, DD/ID, schizophrenia, and other NDDs [25,78,79,80,81,82]. The gene discussed is GRIN2B; the disease is epilepsy.