The enrichment of inhibitory neuronal expression among ASD candidate genes provides molecular support for the finding that deficits in inhibitory neuronal function occurs in some syndromes with autism-associated behaviors, such as individuals with ARX mutations70,71, Dravet syndrome caused by loss-of-function mutations in SCN1A72, and Tuberous Sclerosis caused by mutations in TSC1/273,74 (for review, see ref. 75). This evidence concerns the gene ARX and tuberous sclerosis.