Notably, A2A-D2 heteromers emerging from the interaction of the adenosine A2A receptor and the dopamine D2 receptor in the striatal neuron plasma membrane opened up new comprehension of the Parkinson’s disease (PD) pathophysiology and of the adverse anti-Parkinson’s drug reaction [8,19,20,21,22,23,24,25,26,27]. This evidence concerns the gene DRD2 and Parkinsonism.