Therefore, in this study we use 123I-Ioflupane SPECT, a widely available dopamine transporter imaging modality, to (i) assess dopamine transporter levels in the striatum of patients with FTD, compared with PD and healthy controls, (ii) assess the putamen-to-caudate ratio, reflecting the distribution pattern of striatal dopaminergic loss in FTD, compared with PD and healthy controls, and (iii) explore whether dopamine transporter levels in the striatum are associated with cardinal clinical manifestations of FTD, namely social cognition and language. The gene discussed is SLC6A3; the disease is Parkinson disease.