Abstract: Objective To study the clinical features and treatment of pyridoxal-reponsive epilepsy encephalopathy caused by KCNQ 2 gene mutation. Methods The clinical data of two patients diagnosed with pyridoxal-responsive epilepsy encephalopathy caused by KCNQ 2 gene mutation were retrospectively analyzed, and related literature were reviewed. Results Case 1 is a female child with onset age of 6 days after birth, and case 2 is a male child with onset age of 7 months of age, both of them showed refractory seizures, accompanied by mental and motor developmental retardation. Treatment with sodium channel blockers and other anti-epileptic drugs is ineffective. The number of seizure attack gradually decreased after the add-on treatment of high-dose vitamin B6 . Pathogenetic variations of KCNQ 2 were confirmed by genetic testing: c. 2312 C>T; p.Thr 771 Ile and c.873G>C; p.Arg 291 Ser. Conclusion The age of onset of epilepsy caused by KCNQ 2 gene mutation is early, often combined with mental and motor retardation. In patients who have no effect on sodium channel blocker treatment may have pyridoxal dependence, which could try the high-dose of vitamin B6 treatment.

Key words: KCNQ 2 gene; gene mutation; pyridoxal-reponsive; epileptic encephalopathy; vitamin B6