These include TRIO, RAI1, MTOR, TSC2 and RELN. All these genes are implicated in NDDs, two of which are implicated in specific syndromes, namely RAI1 (Smith-Magenis Syndrome) and TSC2 (Tuberous Sclerosis) Both Smith-Magenis syndrome and Tuberous Sclerosis are known to be associated with moderate to severe intellectual disability in humans and are also characterised by other medical and neuropsychiatric features. Here, TSC2 is linked to tuberous sclerosis.