However, in more recent years, the advent of next-generation sequencing (NGS) technologies has led to the increasing identification of pleiotropic genes such as GNAO1, SCN8A, FOXG1, and SYNGAP1, known to cause developmental and epileptic encephalopathies (DEEs) or complex neurodevelopmental syndromes. Here, SYNGAP1 is linked to developmental and epileptic encephalopathy.