In an exome sequencing study of ADHD patients without a family history of ADHD, Kim et al. [142] reported six de novo missense SNVs in brain-expressed genes: TBC1D9, DAGLA, QARS, CSMD2, TRPM2, and WDR83. They also sequenced 26 genes implicated in ID and ASDs but found only one potentially deleterious variant. This evidence concerns the gene CSMD2 and attention deficit-hyperactivity disorder.