Interestingly, although pathological examinations were not performed in the present study, in addition to the decrease of tracer uptake in dopamine transporter SPECT, decreased cardiac uptake in 123I-MIBG scintigraphy was also demonstrated in our patients with parkinsonism, consistent with Lewy body-related conditions such as Parkinson’s disease and dementia with Lewy bodies23. Here, SLC6A3 is linked to Parkinson disease.