GRIN2B and Huntington disease: Evidence suggests that NR2B-containing NMDARs contribute to the degeneration of medium spiny neurons (MSNs) in the striatum of HD patients [5], [6], and NR2B-containing extrasynaptic NMDARs have been shown to have increased surface expression, current, and toxicity in striatal MSNs in HD mouse models [5], [7], [8].