To our knowledge, this study is the first to investigate the interaction effects of GIT1 rs550818 and DRD4 48 bp VNTR gene variants on CPT variables such as commission errors and response time variability, which are well‐established neurocognitive endophenotypes of ADHD (Kebir & Joober, 2011). This evidence concerns the gene DRD4 and attention deficit-hyperactivity disorder.