According to many association studies followed by meta-analysis, it has been shown that the 10-repeat allele of the DAT1 is a risk allele for ADHD in childhood (Gizer et al. 2009; Table 2), while persistent ADHD in adults was associated with the 9-repeat allele (Franke et al. 2010), findings that might point to a regulatory effect of DAT in brain development. The gene discussed is SLC6A3; the disease is attention deficit-hyperactivity disorder.