Alterations in the ratio of GluN2B-containing NMDARs and GluN2A-containing NMDARs at synapses on MSNs correlate with dysfunctional motor behaviors, which has been thought to underlie striatum-related neurologic disorders such as Parkinson’s disease (PD) and Huntington’s disease (HD; Gardoni and Bellone, 2015). Here, GRIN2A is linked to juvenile Huntington disease.