The role of PARK2 mutations in Parkinson’s patients are relatively well studied and recent studies also utilize human-induced pluripotent stem cell (hiPSC)-derived neuronal cells [22,23] in this context, but no data are available yet regarding the functional consequences of PARK2 CNVs associated with ADHD in human-derived cellular models. This evidence concerns the gene PRKN and attention deficit-hyperactivity disorder.