SDK1 and attention deficit-hyperactivity disorder: SDK1 (The Sidekick Cell Adhesion Molecule 1) has been associated with ASD [21,22,23,24], and ADHD [25,26]; CHD2 (Chromodomain Helicase DNA Binding Protein 2) variants has been identified in individuals with central nervous system pathologies [27]; and CLN8 (the ceroid-lipofuscinosis, neuronal 8) has been linked to ASD through rare missense variants found in a Japanese family [28].