Therefore, to disclose the suspected lateralised basal ganglia dysfunction on sensorimotor aspects of speech production, we aimed to objectively compare speech in de novo, drug-naive patients with PD with lower degrees of right and left dopamine transporter (DAT) availability in putamen defined using dopamine transporter single-photon emission CT (DAT-SPECT). This evidence concerns the gene SLC6A3 and Parkinson disease.