A2AR heteromers can be found in several combinations, including A1R-A2AR, A2AR-A2BR, A2AR-D2R, A2AR-D3R, and A2AR-D4R4; however, the A2AR-D2R heteroreceptor complex is of the greatest interest as it plays a role in Parkinson’s disease, schizophrenia, and cocaine addiction [53]. The gene discussed is DRD2; the disease is cocaine dependence.