Vitamin B6-Responsive Epilepsy due to a Novel KCNQ2 Mutation

Mutations in KCNQ2, encoding for subunits of potassium channels, are known to cause neonatal epileptic encephalopathy (NEE). Therapeutic options for these children are often limited. Recently, there are indications that some patients with KCNQ2 NEE show seizure response to vitamin B₆ (VB₆) therapy. We present a young infant with severe KCNQ2 encephalopathy resulting from a novel de novo mutation (c.1023G>C; p.(Gln341His)). In our patient, VB₆ responsiveness could be demonstrated clearly by remarkable seizure-response to VB₆ therapy and seizure exacerbation to discontinuation of VB₆ therapy. The pathophysiology of VB₆ response in potassium channel mutations is not understood. Some hypothetical mechanisms are currently in discussion. To identify the group of patients who benefits from VB₆ therapy, further investigations are necessary.