The main reason for the combined DAT therapy in these patients was prolonged OFF time after the introduction of STN-DBS as well as other symptoms refractory to STN-DBS, such as axial symptoms and uncontrollable dyskinesias [6,21,24], due to incorrect patient selection or disease progression requiring high stimulation amplitudes, which can lead to disabling side effects as a result of current spread [6]. This evidence concerns the gene SLC6A3 and Dyskinesia.