We previously examined gene expression profiles in the brain, and found that 6 SHRSP-specific genes isolated from the rats at 6 weeks of age (Agtr1b, Arc, Egr2, Fos, Hspa1b and Snca) were annotated to ‘behavior' and were suggested to participate in the genesis of ADHD (5). This evidence concerns the gene EGR2 and attention deficit-hyperactivity disorder.