CLOCK and attention deficit-hyperactivity disorder: Similar rare variants, CNVs and GWAS single nucleotide polymorphisms have been implicated through anomalies of a gene set labelled CLOCK (circadian locomotor output cycles kaput) genes; these anomalies are specifically linked to sleep disorders in ASD/ADHD.50 Charrier and associates consider these linkages and the numerous genes involved; however, these are too detailed to discuss in this review.47