Specific attention was paid during WES to early infantile epileptic encephalopathy (EIEE) related genes (AARS, ALG13, ARHGEF9, ARV1, ARX, CACNA1A, CDKL5, DNM1, DOCK7, EEF1A2, FRRS1L, GABRA1, GABRB3, GNAO1, GRIN2B, GUF1, HCN1, ITPA, KCNA2, KCNB1, KCNQ2, KCNT1, NECAP1, PCDH19, PIGA, PLCB1, PNKP, SCN1A, SCN2A, SCN8A, SCN9A, SLC12A5, SLC13A5, SLC1A2, SLC25A12, SLC25A22, SLC35A2, SPTAN1, ST3GAL3, STXBP1, SZT2, TBC1D24, WWOX, AP3B2, KCNT2, HNRNPU, CAD, UBA5, FGF12, GABRB1, MDH2, YWHAG, DENND5A, SCN1B, GRIN2D, SYNJ1, SIK1), to TSC1 and TSC2 and to IKBKG-related disorder. This evidence concerns the gene SZT2 and genetic developmental and epileptic encephalopathy.