DRD2 and Parkinson disease: The main but not sufficient mechanism is the blockade of D2Rs in the striatum, but it has also been proposed that the rate APs dissociate from the D2R may predict their likelihood to cause parkinsonism; with transient D2 blockade (fast dissociation) being less likely (e.g., clozapine, quetiapine), in addition to gene expression changes induced by APs.