Association of the DAT1 genotype with inattentive behavior is mediated by reading ability in a general population sample

► ADHD and reading disability co-occur in the child population suggesting a shared etiology. ► We examined the involvement of the DAT1 gene in reading disability after controlling for ADHD symptoms. ► Our findings indicate the association of DAT1 with ADHD may reflect the influence of reading ability. ► This novel association supports the utility of a quantitative trait loci (QTL) approach. Attention deficit hyperactivity disorder (ADHD) and reading disability (RD) frequently co-occur in the child population and therefore raise the possibility of shared genetic etiology. We used a quantitative trait loci (QTL) approach to assess the involvement of the dopamine transporter (DAT1) gene polymorphism in mediating reading disability and poor attention in a general population sample of primary school children aged 6–11 years in the UK. The potential confounding effects of IQ and chronological age were also investigated. We found an independent association between the homozygous DAT1 10/10 repeat genotype and RD that was not accounted for by the level of ADHD symptoms. This finding suggests that the DAT1 gene polymorphism may influence a common neural mechanism underlying both reading acquisition and ADHD symptoms.