At present, there are no data to justify the use of selective DAT or dual DAT = NET inhibitors as adjunct therapy to L-DOPA and, if triple DAT = NET = SERT inhibitors may effectively extend duration of L-DOPA anti-Parkinsonian effect, the additional on-time appears to be associated with an exacerbation of dyskinesia, somewhat off-setting the favourable effect on on-time duration. The gene discussed is SLC6A4; the disease is drug-induced dyskinesia.