In the cross-sectional cohort, DAT availability in the putamen and substantia nigra of patients with Parkinson’s disease showed a significant negative association with total motor severity (r = −0.59, P = 0.002 for putamen; r = −0.46, P = 0.018 for substantia nigra), but not tremor severity. The gene discussed is SLC6A3; the disease is Tremor.