Effects of the ketogenic diet therapy in patients with STXBP1-related encephalopathy

Objective: We aimed to investigate the effects of ketogenic diet (KD) and modified Atkins diet (MAD) in patients with epileptic encephalopathy, caused by the STXBP1 (syntaxin-binding protein 1) gene mutation. Methods: We retrospectively evaluated the data of patients with STXBP1-related epileptic encephalopathy who were started on either KD or MAD between January 1, 2005, and June 30, 2021, in Severance Children's Hospital. Results: Twelve patients were examined. The median age of seizure onset was 1.5 months [interquartile range (IQR): 0–3] with a median age of dietary therapy initiation at 4.5 months (IQR: 3.0–9.3) and a median diet duration of 6.5 months (IQR: 2.8–13.3). The patients had various epilepsy syndromes: nine (75 %) patients had early infantile developmental and epileptic encephalopathy, two (16.7 %) had infantile epileptic spasms syndrome, and one (8.3 %) had developmental and epileptic encephalopathy. Three patients (25 %) were definite KD responders who achieved seizure freedom within the median of 2 months from KD initiation and remained seizure-free for a median of 36 months (IQR: 29.5–60.0). One patient (8.3 %) was a possible KD responder, seizure-free with KD initiation and steroid therapy while 8 were non-responders (66.7 %). The definite KD responders shared similar clinical characteristics as the rest, except that there were significantly more patients that had seizure onset at ≥ 6 months (p = 0.045) in the definite KD responder group. Conclusion: We demonstrated dietary therapy was highly effective for some patients with STXBP1-related epileptic encephalopathy, especially those with later onset.