A crucial role of SHANK3 mutations in this context is supported by the following three facts: 1) SHANK3 haploinsufficiency is the critical factor for the development of neuropsychiatric symptoms in 22q13 deletion syndrome, also known as Phelan-McDermid syndrome, 2) the current prevalence for SHANK3 mutations in individuals with ASD in general is between 0.5% and 0.7%, and 3) data indicate that a SHANK3 mutation is present in approximately 2% of individuals with both ASD and intellectual disability (ID) [16-18]. Here, SHANK3 is linked to Phelan-McDermid syndrome.