Outcome of ketogenic diets in GLUT1 deficiency syndrome in Japan: A nationwide survey.

OBJECTIVES To evaluate the outcome of ketogenic diets (KDs) in patients with glucose transport type 1 deficiency syndrome (GLUT1DS) in Japan. METHODS A nationwide survey for GLUT1DS was conducted by sending questionnaires to board-certified pediatric neurologists nationwide to obtain clinical and laboratory data. RESULTS Among 39 patients whose diagnosis was confirmed molecularly or by the 3-O-methylglucose uptake assay, 31 were treated with KDs for longer than 1month. Seventeen patients (55%) were on the modified Atkins diet, 11 (35%) were on the classic KD, and 3 were on the medium-chain triglyceride (MCT) diet. The median values and ranges of serum β-hydroxybutyrate levels in patients on the modified Atkins diet, classic KD and MCT diet were 2.5mM (0.75-4.1), 1.7mM (0.23-3.5) and 2.6mM (1.5-3.0), respectively. The KDs were effective on seizures (80%), aggravation after fasting (80%) and ataxia (79%). Thus, ataxia was as responsive as seizures. Two patients on the classic KD with a ketogenic ratio as low as 1:1 showed improvement in neurological symptoms. The development or intelligence quotient measured using the same psychological scales before and after the KDs in 9 patients did not show a significant improvement; the median quotients before and after the diets were 40 (12-91) and 46 (12-67). CONCLUSION The KDs were most effective on seizures, transient aggravation after fasting and ataxia. The efficacy on intellectual development was equivocal. The modified Atkins diet was more commonly used for GLUT1DS in this study, and its ketogenicity was equivalent to the classic KD.