However, serotonergic neurons lack mechanisms regulating DA release, such as DA D2 autoreceptors and DAT; hence, the uncontrolled release of L-DOPA-derived DA (Tanaka et al. 1999; Carta et al. 2007) and fluctuations in its extracellular level may play a causative role in the appearance of dyskinesias (Carta and Bezard 2011; Mosharov et al. 2015). This evidence concerns the gene SLC6A3 and Dyskinesia.