CNR1 and Huntington disease: CNR1 is highly expressed in the basal ganglia where it modulates synaptic functions involved in motor behaviour.76 Early downregulation of CNR1 has been reported in the striatum of HD patients.4,44 Levels of CNR1 were decreased in late HD compared with controls (P = 0.055) and preHD (P = 0.108) and were significantly reduced in CSF from late HD compared early/mid HD (P = 0.008).