However, a later PET study using the radioligand (S)-N-((1-ethyl-2-pyrrolidinyl)methyl)-5- bromo-2,3-dimethoxybenzamide ([11C] FLB 457) with high-affinity for dopamine D2 receptors found no difference between extrastriatal (thalamus, temporal cortex, cerebellum) D2 receptor binding in HD patients compared to normal controls [13]. This evidence concerns the gene DRD2 and Huntington disease.