In patients with PD, worse storage symptoms correlated with lower DAT binding levels in the less affected side of the caudate (r = −0.196, p=0.001), the more affected side of the caudate (r = −0.168, p=0.005), the less affected side of the putamen (r = −0.291, p < 0.001), and the more affected side of the putamen (r = −0.135, p=0.025) (Figure 1). This evidence concerns the gene SLC6A3 and Parkinson disease.