CHAT and Huntington disease: One of the hallmarks of the HD striatum is loss of proteins associated with acetylcholine (ACh) release by ChIs; expression of both the synthetic enzyme for ACh synthesis—choline acetyltransferase—and the vesicular transporter for ACh (vAChT) are down-regulated in HD striata (Bird and Iversen, 1974; Smith et al., 2006).