Highly and almost exclusively expressed in striatal MSNs, Pde10a plays a critical role in regulating striatal activity and basal ganglia circuitry.[30, 31] Blocking PDE10A with specific antagonists has previously reduced symptoms of Huntington's disease (HD) and Parkinsons's disease (PD) in mice, rats, and monkeys, although PDE10A expression is reduced in both disorders.[32, 33, 34] We now also show reduced Pde10a expression in Foxp1± animals. The gene discussed is PDE10A; the disease is juvenile Huntington disease.