ARPP21 and Huntington disease: Among the 45 key HD genes, the commonly dysregulated genes in mice were Ryr1, Scn4b, Gpr6, Hrh3, Foxp1, Gpr88, Rgs9, Pde10a, Arpp21, Adora 2a, Adcy5, Drd2, Pcp4 (Supplementary Figure S6A).