SLC6A3 and attention deficit-hyperactivity disorder: One of these VNTRs (rs28363170), located on the dopamine transporter gene (SLC6A3 / DAT1) in the 3′ untranslated region (UTR), with the 10- and 9-repeat alleles that are most common (Doucette-Stamm et al. 1995), were found to be associated with ADHD.