Further information on the relationship between A2A receptors and L-DOPA-induced dyskinesias has been provided by Ramlackhansingh et al., who investigated adenosine A2A receptor availability in the caudate and putamen of PD patients with (n = 6) and without L-DOPA-induced dyskinesias (n = 6) and in age-matched healthy controls (n = 6) [46]. The gene discussed is ADORA2A; the disease is drug-induced dyskinesia.