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). The gene discussed is FOS; the disease is attention deficit-hyperactivity disorder.