Although ASD, ADHD, schizophrenia, and ID have clinically distinctive defining features, one key and consistent finding is that the CNVs associated with each of these disorders show significant overlap with each other.1, 5 That is, the same CNV is associated with increased risk of different types of disorders: this is known as pleiotropy. This phenomenon is most consistently observed for disorders considered to have strong neurodevelopmental origins (ASD, ADHD, schizophrenia, and ID). This observation highlights that the same genetic risks operate across diagnostic categories. That is also true for other risk factors.
