The relationship between EBW polymorphism and PIK3CG (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit γ) was indicated: rs12667819 (p = 0.014) in the non-ADHD group; COMT (catechol-O-methyltransferase): rs4680 (p = 0.048) in the ADHD group. This evidence concerns the gene PIK3CG and attention deficit-hyperactivity disorder.