Table 5.

Clock genes and autism spectrum disorder (ASD).

Studies	Measure	Individuals with Psychiatric Disorder (n)	Controls (n)	Results
Nicholas et al. [89]	Screening of eleven clock/clock-related genes	High-functioning ASD individuals (n = 110)	Healthy parents (n = 220)	Significant association for two single-nucleotide polymorphisms in Per1 and in Npas2.
Yang et al. [168]	Direct sequencing analysis of the coding regions of 18 canonical clock genes and clock-controlled genes	ASD individuals with sleep disorders (n = 14); ASD individuals without sleep disorders (n = 14)	Healthy individuals (n = 23)	Mutations in circadian-relevant genes (specifically Per1, Per2, Per3, Clock, Npas2, Bmal1, Tim, Cry1, Cry2, Dbp and Ck1ε) affecting gene function are more frequent in individuals with ASD than in controls.