D-glucose is an essential fuel for metabolism in mammalian cells and the predominant fuel source for the brain. Transport of glucose across tissue barriers is mediated by stereospecific transporter proteins. Glut-1 is a major glucose transporter expressed on vascular endothelial cells comprising the blood brain barrier and is responsible for glucose entry into the brain. Impaired glucose transport across the blood brain barrier results in Glut-1 deficiency syndrome(DS). It is caused by haploinsufficiency of the blood brain barrier hexose carrier. Heterozygous mutations or hemizygosity of the GLUT-1 gene cause Glut-1 DS. It is characterized by infantile seizures refractory to anticonvulsants, developmental delay, acquired microcephaly, spasticity, ataxia, opsoclonus and other paroxysmal neurological phenomena, often occurring prior to meals. The diagnosis of Glut-1 DS is established in neurologically impaired patients with reduced cerebrospinal glucose concentration(hypoglycorrhachia) and lactate concentration in the absence of hypoglycemia. Decreased 3-O-methyl-D-glucose uptake in erythrocytes also supports the diagnosis of Glut-1 DS. Several treatment strategies have been pursued, none optimal, as it relates to the developmental encephalopahty associated with this clinical syndrome. Ketogenic diet has been effective in controlling seizures but has had little measurable effects on the associated cognitive impairments and behavioral disturbance. Current treatment is inadequate, and future studies should be directed at the mechanisms designed to upreglulate GLUT-1 expression, thereby increasing residual Glut-1 activity to 75 to 100%.
3-O-Methylglucose ; Anticonvulsants ; Ataxia ; Blood-Brain Barrier ; Brain ; Diagnosis ; Endothelial Cells ; Epilepsy ; Erythrocytes ; Glucose Transport Proteins, Facilitative* ; Glucose Transporter Type 1* ; Glucose* ; Haploinsufficiency ; Humans ; Hypoglycemia ; Ketogenic Diet ; Lactic Acid ; Meals ; Metabolism ; Microcephaly ; Muscle Spasticity ; Ocular Motility Disorders ; Seizures

Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is caused by impaired glucose transport across the blood-brain barrier (BBB) and characterized by infantile seizures, developmental delay, acquired microcephaly, spasticity, ataxia, and a low cerebrospinal glucose concentration (hypoglycorrhachia). A diagnosis of GLUT1-DS is biochemically established in neurologically impaired patients with hypoglycorrhachia in the normoglycemia. GLUT1-DS can be confirmed by mutation analysis of the solute carrier family 2 (facilitated glucose transporter), member 1 (SLC2A1) gene or reduced 3-O-methyl-D-glucose uptake into erythrocytes. The patient was a 12-year-old boy born at term. He had experienced seizures from 4 months of age. Electroencephalography (EEG) did not show epileptiform activity. Brain magnetic resonance imaging (MRI) revealed mild diffuse cortical atrophy and ventricular dilatation. Furthermore, he showed developmental delay, mental retardation, and ataxia, which all became more apparent with age progression. For 7 years, he had experienced paroxysmal episodes of atonic behavioral changes that were aggravated before meals or when he became tired. When he was 12 years old, cerebrospinal fluid (CSF) analysis revealed a low glucose concentration in the normal serum glucose and lactate levels. Under the impression of GLUT1-DS, mutation analysis of the SLC2A1 gene by direct sequencing was performed using white blood cells, and c.680-2delA of intron 5 was found. We describe a GLUT1-DS patient with a typical natural history of GLUT1-DS through a long term follow-up visits, with a novel splice site mutation (SLC2A1: c.6802delA).
3-O-Methylglucose ; Ataxia ; Atrophy ; Blood Glucose ; Blood-Brain Barrier ; Brain ; Cerebrospinal Fluid ; Child ; Diagnosis ; Dilatation ; Electroencephalography ; Erythrocytes ; Follow-Up Studies ; Glucose ; Glucose Transport Proteins, Facilitative* ; Glucose Transporter Type 1 ; Humans ; Intellectual Disability ; Introns ; Lactic Acid ; Leukocytes ; Magnetic Resonance Imaging ; Male ; Meals ; Microcephaly ; Muscle Spasticity ; Natural History ; Seizures