PDE1B and juvenile Huntington disease: Some of the proteins we found downregulated in the striatum of Huntington’s disease mice are known to be involved in cAMP and cGMP metabolic processes, such as adenylate cyclase type 5 (ADCY5), calcium/calmodulin-dependent 3′,5′-cyclic nucleotide phosphodiesterase 1B (PDE1B) and the cyclic nucleotide phosphodiesterase 10A (PDE10).