In a demonstration of the power of studying rare neurogenetic conditions to understand the pathophysiology underlying more common idiopathic disorders, we, and others, have shown, on the basis of work predicting steroid sulfatase involvement in (in)attention from TS and related mouse models, that polymorphisms within STS are associated with the inattentive symptom count in boys diagnosed with idiopathic ADHD [61, 62]. This evidence concerns the gene STS and attention deficit-hyperactivity disorder.