Abstract: 　Objective　To explore the phenotypic characteristics of Ohtahara syndrome caused by SCN2A gene mutation (SCN2A-OS) and clinical application of phenytoin sodium. Method　The phenotypic characteristics, clinical diagnosis, treatment and prognosis in 2 children with SCN2A-OS diagnosed and treated in October 2017 were retrospectively analyzed, and the related literature was reviewed. Results　Both the two children were male, and the age at onset of the disease was 1 day and 2 months respectively. Both of them had spasm and tonic seizures and developmental delay. Electroencephalogram (EEG) results showed burst-suppression. Many kinds of antiepileptic drugs were ineffective. The treatment with phenytoin was effective, and no obvious adverse reactions were observed in the recent follow-up. A new missense mutation of SCN2A gene, c.2995G>A (NM_021007), was detected in case 1, and another new missense mutation of c.4015A>G was detected in case 2, and both were the first reported. At present, 25 children with SCN2A-OS have been reported at home and abroad. The onset age of epilepsy fluctuated from 1 day to 60 days after birth (median age was 1 day), and the most common initial epilepsy type was tonic seizure. EEG of all children showed typical burst-suppression features and 52% of them turned to hypsarrhythmia later. During follow-up period, seizure free was in 11 children and phenytoin was effective in 9 children. Conclusion　SCN2A-OS patients have seizure onset at early age, poor prognosis and poor response to multi-antiepileptic drugs. Phenytoin could control seizure effectively.

Key words: SCN2A gene;　Ohtahara syndrome;　phenytoin