Recent investigations of structural variation in autism and schizophrenia have found increased de novo and/or overall variation in diseased individuals, leading to the speculation that these diseases may have a sizable number of possible molecular etiologies.15, 19, 21, 52, 53 To date, this theory is consistent with the general lack of success of genetic association studies in identifying common causative variants in neuropsychiatric disorders, including ADHD.54 Our results further support this hypothesis, as we found a wide distribution of genes specifically affected by CNVs in our ADHD probands relative to controls, many of which were associated with neurodevelopmental pathways and disorders.
