Previous genetic investigations, consisting of array CGH, screening for Angelman syndrome (methylation and sequencing of UBE3A) and Fragile X Syndrome (FMR1), sequencing of FOXG1, CDKL5, STK9, RAI1, MECP2, MEF2C, and trio ES, had returned normal results. This evidence concerns the gene UBE3A and Angelman syndrome.