TSC2 and Intellectual disability: 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.