SLC6A3 and Parkinson disease: The evidence that a number of ET + RT cases had an abnormal DAT-SPECT, despite no or minimal evidence of parkinsonism beyond RT, is supported by some imaging studies demonstrating basal ganglia involvement in these patients (Caligiuri et al. 2017; Nicoletti et al. 2015) and corroborate the admittedly controversial hypothesis that ET might evolve in PD (Bellows and Jankovic 2022, 2021).