We first investigated known syndromic causes of ASD in all identified ASD-affected individuals, namely, fragile X syndrome (caused by CGG expansion in FMR1), Rett syndrome (caused by mutations in MECP2), and Tuberous Sclerosis (caused by mutations in TSC1 or TSC2), as explained in Figure 1. This evidence concerns the gene FMR1 and atypical Rett syndrome.