SLC6A3 and Parkinson disease: Another case‐control study conducted in Finland investigated differences in the binding of striatal dopamine transporter and the extent of caudate dopamine terminal loss, and the consequent dopamine function was relatively more preserved in PD patients with tremor compared to akinetic‐rigid patients (Kaasinen, Kinos, Joutsa, Seppänen, & Noponen, 2014).