The DYX7 locus on chromosome 11p15 was found by a targeted study of the dopamine receptor D4 (DRD4) as a candidate for dyslexia based on its postulated involvement in Attention deficit/hyperactivity disorder (ADHD) and the frequent co-occurrence of the two disorders (Hsiung et al., 2004). Here, DRD4 is linked to attention deficit-hyperactivity disorder.