All the 5 de novo variants were listed in ClinVar database, including c.830A>C in PAFAH1B1, c.680T>G in SCN1A, c.226-2A>G in TSC2, and c.341G>A in FGF12. A heterozygous came from his parents Dravet syndrome (DS) is a severe developmental and epileptic encephalopathy. The gene discussed is SCN1A; the disease is developmental and epileptic encephalopathy.