In PD, the 5-hydroxytryptamine type 3 (5-HT3) antagonist ondansetron and the 5-HT2 reverse agonist pimavanserin have been used to treat visual hallucinations.34 Since 5-HT receptors can modulate release of GABA,35 it may be that the mode of action of these drugs in treating hallucinations is partly through their effect on GABA. Here, HTR2A is linked to Visual hallucination.