If confirmed, the HTR6 rs1805054 polymorphism, alone and especially in combination with the SLC6A3 3′UTR VNTR polymorphism, could serve as a pharmacogenetic predictor of AIP, which would be potentially helpful in tailoring personalized therapeutic strategies for the patients at increased risk of developing drug-induced parkinsonism or already suffering from this EPS. Here, HTR6 is linked to Parkinson disease.