Of note, PD duration was negatively correlated with DAT-BPND values in the left striatum (left caudate: R = −0.65, P < 0.03; left putamen: R = −0.66, P < 0.02) (i.e., patients with longer disease duration displayed significantly lower left striatal DAT-BPND values) while a borderline effect was found in the right striatum (right caudate: R = −0.50, P = 0.09; right putamen: R = −0.55, P = 0.06) (Fig. 1). This evidence concerns the gene SLC6A3 and Parkinson disease.