Impaired glucose transport into the brain: the expanding spectrum of glucose transporter type 1 deficiency syndrome

Purpose of review Glucose transporter type 1 deficiency syndrome (OMIM 606777) is a treatable epileptic encephalopathy resulting from impaired glucose transport into the brain. In recent years, the increasing number of patients has generated substantial insights into the manifestations and mechanisms of this disease. Current understanding of this novel disorder is reviewed, and recent advances in diagnosis and treatment are highlighted. Recent findings The syndrome is now understood to be a complex neurological disorder. The clinical spectrum has recently been extended by infants with `benign' transient hypoglycorrhachia, glucose transporter type 1 deficiency syndrome without seizures, and by adult cases. Other key findings in the last couple of years include (1) the description of electroencephalogram abnormalities, (2) a characteristic cerebral metabolic footprint in positron emission tomography imaging, and (3) the definition of molecular mechanisms and functional domains within the glucose transporter type 1 protein by in-vitro mutagenesis. The disease has also shed a new light on the mechanisms and the effectiveness of the ketogenic diet for seizure control. Summary The syndrome is now well characterized in children and should be considered in any patient with intractable epilepsy. An effective therapy is available. The clinical spectrum and the molecular basis of the disease are increasingly heterogeneous and indicate complex pathogenic mechanisms that will ultimately lead to a classification on clinical, biochemical, and molecular grounds.