GRIN2B and early-onset autosomal dominant Alzheimer disease: Extra-synaptic NMDARs are enriched in GluN2B-containing heterodimers (GluN2B-NMDARs) and its activity has been associated with neuronal death, in particular in neurodegenerative disorders such as Huntington’s or Alzheimer’s disease (Papouin and Oliet, 2014).