ADRA2A and attention deficit-hyperactivity disorder: With regard to the findings in the genetic analysis, the results of risk association with ADHD in the children carrying ADRA2A rs553668 GG or AG genotype were in concordance with the findings of several studies, and indicated that rs553668, being known as the DraI site in the 3′-untranslated region of ADRA2A gene, A-to-G variant increased the risk of ADHD24,25.