The combined action of DAT and SERT inhibition could thus lead to more physiological dopamine signalling than inhibition of either alone; indeed keeping this in balance, as opposed to inhibiting SERT more than DAT, could be one further mechanism explaining why UWA-101, unlike S-MDMA, did not exacerbate dyskinesia severity. This evidence concerns the gene SLC6A3 and drug-induced dyskinesia.