DRD2 and Parkinson disease: Interestingly, the binding of 11C-(+)-PHNO to the D2 receptor in the ventral striatum was found to be modulated by SNPs of the DRD2 gene resulting in alternative splicing into long, mainly postsynaptic, and short, mainly presynaptic autoreceptor, variants in a study with 20 PD patients [38], although replication is critical for genetic association studies.