The most common single-gene mutations in ASD with ID are associated with Fragile X syndrome (FXS; FMRI), Tuberous Sclerosis (TSC1, TSC2), Angelman Syndrome (UBE3A), Rett Syndrome (MECP2), and Phlean-McDermid syndrome (SHANK3). The gene discussed is UBE3A; the disease is fragile X syndrome.