Olanzapine, quetiapine, and aripiprazole are atypical antipsychotics with both D2 and 5-HT2A antagonist properties that have been used in functional GI disorders (FGIDs), particularly for nausea and abdominal pain symptoms, and are increasingly being used as augmentation in refractory gastroparesis [100]. This evidence concerns the gene HTR2A and gastroparesis.