5HT2A has also been implicated in PD-hallucinations; evidenced by the higher density of 5HT2A receptors within frontal, temporal and occipital regions in patients with PD hallucinations in post mortem and in vivo studies43,64 and the efficacy of the novel 5HT2A inverse agonist Pimavanserin in the treatment of PD-hallucinations65. The gene discussed is HTR2A; the disease is Parkinson disease.