Selected genetic syndromes that are known etiologies of ASD: 22q11.2 deletion syndrome, including velo-cardio-facial syndrome (Shprintzen); Angelman syndrome; CHARGE syndrome; Cornelia de Lange syndrome; Fragile X syndrome; Mutations in MED12 (Lujan-Fryns syndrome); Prader-Willi syndrome; Mutations in PTEN ‒ Phosphatase and Tensin (Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome); Rett syndrome; Smith-Lemli-Opitz syndrome; Smith-Magenis syndrome; Sotos syndrome; and Tuberous sclerosis. This evidence concerns the gene MED12 and atypical Rett syndrome.