Given that the expression levels of both VMAT2 and dopamine transporter (DAT) in the striatum are similar between R1441G and WT animals, the lower DA uptake after reserpine treatment in the KI mice indicates an altered DAT function and increased susceptibility to DA depletion that may reflect the earliest presynaptic dysfunctions in PD mediated by pathogenic LRRK2. This evidence concerns the gene SLC18A2 and Parkinson disease.