To address the effect of AAV5-miHTT-155 and AAV5-miSNP67T-155 treatments on HD-linked neuronal dysfunction, we stained for dopamine- and cyclic-AMP-regulated phosphoprotein of 32 kDa(DARPP-32), a phosphoprotein widely expressed in medium spiny neurons.24 Consistent with the low accumulation of mutant HTT aggregates, we observed a significant reduction of DARPP-32 lesion size two months after AAV5-miHTT-155 (0.19 mm3±0.11, P⩽0.0001) or AAV5-miSNP67T-155 (0.62 mm3 ± 0.19, P⩽0.0001) treatments compared with the saline control (1.92 mm3±0.29) (Figures 2e and f). The gene discussed is PPP1R1B; the disease is Huntington disease.