A retrospective study analyzing (123I-FP-CIT) dopamine transporter (DAT) from monogenic PD patients with mutations in either GBA1, LRRK2, SNCA, PINK1, or Parkin reported greater asymmetrical striatal dopaminergic uptake in GBA1 and LRRK2 carriers compared with SNCA, PINK1, and Parkin carriers [24]. This evidence concerns the gene SLC6A3 and Parkinson disease.