Imbalances in the dopamine system are hypothesized to contribute to the pathophysiology of ADHD (10), and knockdown of ADGRL3 in fish, as well as knockout in flies, mice, and rats, disrupts normal dopamine signaling and leads to abnormalities in dopamine-related behaviors, most notably increased locomotor activity (11–17). This evidence concerns the gene ADGRL3 and attention deficit-hyperactivity disorder.