Reduction of DAT radiotracer binding, as assessed by single‐photon emission computed tomography neuroimaging, reflects dopaminergic nerve terminal degeneration in subjects with PD, which precedes the onset of clinical symptoms.6 DAT‐selective radioligand [123I]N‐ω‐fluoropropyl‐2β‐carbomethoxy‐3β‐[4‐iodophenyl]nortropane is the one currently approved for differential diagnosis between PD and essential tremor.7, 8 However, there is no current regulatory endorsement for the use of DAT imaging as an enrichment biomarker in clinical trials. The gene discussed is SLC6A3; the disease is essential tremor.