SLC6A3 and Huntington disease: In manifest HD patients, caudate [18F]fluorodopa uptake (targeting dopa decarboxylase) has been found to be reduced [31] or normal [32], [11C]β-CIT levels (targeting striatal dopamine transporter) were 50 % reduced [33] and [11C]DTBZ levels (targeting type-2 vesicular monoamine transporter) showed a gradient from a rostral increase to a caudal decrease in the striatum [34].