Many reliable risk genes for autism development have been discovered (reviewed in [2]), and approximately 5% of autism cases result from single-nucleotide polymorphisms (SNPs) in genes such as NLGN3, NLGN4, NRXN1, MECP2, SHANK3, FMR1, TSC1/2, and UBE3A (reviewed in [2]). Here, MECP2 is linked to autism.