More than 20% of DEE/EE with ESES were identified with monogenic variants, including KCNQ2, KCNA2, GRIN2A, SLC9A6, HIVEP2, and RARS2. With an age-related feature in genetic disorders, ESES could follow the first stage of different EEG patterns in precedence. The gene discussed is KCNQ2; the disease is hereditary disease.