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

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. 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. 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. We demonstrated dietary therapy was highly effective for some patients with STXBP1-related epileptic encephalopathy, especially those with later onset. •Dietary therapy could be highly effective for some patients with STXBP1-related epileptic encephalopathy.•Definite diet responders achieved seizure freedom within 2 months from diet initiation and remained seizure-free even after discontinuation.•Clear delineating phenotypes for definite diet responders and the others had yet to be identified, except that significantly more patients had seizure onset at ≥ 6 months (p = 0.045) in the definite responder group.