CHD8 and attention deficit-hyperactivity disorder: Comorbid biomarkers may blur diagnostic boundaries, whereas autism-specific biomarkers—such as mutations in SHANK3, NRXN1, and CHD8—are directly tied to autism, but may also be found in other conditions like intellectual disabilities and ADHD (Zoghbi and Bear, 2012; De Rubeis and Buxbaum, 2015).