HTR2A and autism spectrum disorder: Interestingly, a set of arylpiperazine derivatives with a mixed 5-HT1A/5-HT7 agonist and 5-HT2A antagonist activity, a good in vitro metabolic stability, drug-like properties and the ability to cross the blood–brain barrier have recently been proposed as a potential tool to treat autism spectrum disorders [114]; based on their mixed pharmacological properties, we suggest that these compounds might be tested in preclinical studies on animal models of Fragile X Syndrome.