Youth with the SLC6A3 3’ UTR 10R/10R genotype showed higher activation in the left striatum, right dorsal premotor cortex, and bilaterally in the temporoparietal cortical junction as compared to the ADHD individuals who were heterozygous for the SLC6A3 3′ UTR 9R allele. This evidence concerns the gene SLC6A3 and attention deficit-hyperactivity disorder.