American Journal of Medical Genetics Part B (Neuropsychiatric Genetics) 147B:1519–1523 (2008) Association of ADHD with Genetic Variants in the 50-Region of the Dopamine Transporter Gene: Evidence for Allelic Heterogeneity

Multiple studies have reported an association between attention deficit hyperactivity disorder (ADHD) and the 10-repeat allele of a variable number tandem repeat (VNTR) polymorphism in the 30-untranslated region (30UTR) of the dopa-mine transporter gene (DAT1). Yet, recent meta-analyses of available data find little or no evidence for this association; although there is strong evidence for heterogeneity between datasets. This pattern of findings could arise for several reasons including the presence of relatively rare risk alleles on common haplotype backgrounds or the functional interaction of two or more loci within the gene. We previously described the importance of a specific haplotype at the 30 end of DAT1, a