RASD2 and Huntington disease: Striatal expression of several key mRNAs, Drd2, Ppp1r1b, Rasd2, Adora2a, and Penk mRNAs, was found to be downregulated in HD mouse striatum compared to control animals (Fig. 5B), consistent with previous reports in human and mouse HD striata as well as in our HD model striatal neurons (Fig. 5A)7, 8, 12.