In a large study of 51 candidate genes, Brookes et al [28] found nominal significance with one or more SNPs in 18 genes, including -839C/T polymorphism of DAT1, with the C allele being significantly over-transmitted to affected ADHD probands (χ2 = 5.58, P = 0.018). Here, SLC6A3 is linked to attention deficit-hyperactivity disorder.