The glucose transporter type 1 deficiency syndrome / 中华神经科杂志

Glucose transporter type 1 deficiency syndrome is a rare neurometabolic disorder caused by mutations of the solute carrier family 2 facilitated glucose transporter member 1 (SLC2A1) gene, characterized by complex manifestations including early onset epilepsy, motor and mental retardation, and movement disorders and so on. Ketogenic-diet is most suitable therapy and should be commenced as early as possible because timing the initiation of the diet may prevent seizure, movement disorder, and cognitive impairment. This review aims to improve the clinicians′ understanding of glucose transporter type 1 deficiency syndrome to ensure the diagnosis as early as possible.

The glucose transporter type 1 deficiency syndrome / 中华神经科杂志

Glucose transporter type 1 deficiency syndrome is a rare neurometabolic disorder caused by mutations of the solute carrier family 2 facilitated glucose transporter member 1 (SLC2A1) gene,characterized by complex manifestations including early onset epilepsy,motor and mental retardation,and movement disorders and so on.Ketogenic-diet is most suitable therapy and should be commenced as early as possible because timing the initiation of the diet may prevent seizure,movement disorder,and cognitive impairment.This review aims to improve the clinicians' understanding of glucose transporter type 1 deficiency syndrome to ensure the diagnosis as early as possible.

Diagnostic Challenges Associated with GLUT1 Deficiency: Phenotypic Variabilities and Evolving Clinical Features

GLUT1 deficiency is a rare neurometabolic disorder that can be effectively treated with ketogenic diet. However, this condition is underdiagnosed due to its nonspecific, overlapping, and evolving symptoms with age. We retrospectively reviewed the clinical course of nine patients diagnosed with GLUT1 deficiency, based on SLC2A1 mutations and/or glucose concentration in cerebrospinal fluid. The patients included eight boys and one girl who initially presented with seizures (44%, 4/9) or delayed development (44%, 4/9) before 2 years of age, except for one patient who presented with apnea as a neonate. Over the clinical course, all of the children developed seizures of the mixed type, including absence seizures and generalized tonic–clonic seizures. About half (56%, 5/9) showed movement disorders such as ataxia, dystonia, or dyskinesia. We observed an evolution of phenotype over time, although this was not uniform across all patients. Only one child had microcephaly. In five patients, ketogenic diet was effective in reducing seizures and movement symptoms, and the patients exhibited subjective improvement in cognitive function. Diagnosing GLUT1 deficiency can be challenging due to the phenotypic variability and evolution. A high index of clinical suspicion in pediatric and even older patients with epilepsy or movement disorders is key to the early diagnosis and treatment, which can improve the patient's quality of life.

Glucose transport 1 deficiency presenting as infantile spasms with a mutation identified in exon 9 of SLC2A1 / 소아과

Glucose transport 1 (GLUT-1) deficiency is a rare syndrome caused by mutations in the glucose transporter 1 gene (SLC2A1) and is characterized by early-onset intractable epilepsy, delayed development, and movement disorder. De novo mutations and several hot spots in N34, G91, R126, R153, and R333 of exons 2, 3, 4, and 8 of SLC2A1 are associated with this condition. Seizures, one of the main clinical features of GLUT-1 deficiency, usually develop during infancy. Most patients experience brief and subtle myoclonic jerk and focal seizures that evolve into a mixture of different types of seizures, such as generalized tonic-clonic, absence, myoclonic, and complex partial seizures. Here, we describe the case of a patient with GLUT-1 deficiency who developed infantile spasms and showed delayed development at 6 months of age. She had intractable epilepsy despite receiving aggressive antiepileptic drug therapy, and underwent a metabolic workup. Cerebrospinal fluid (CSF) examination showed CSF-glucose-to-blood-glucose ratio of 0.38, with a normal lactate level. Bidirectional sequencing of SLC2A1 identified a missense mutation (c.1198C>T) at codon 400 (p.Arg400Cys) of exon 9.

Glucose Transporter Type 1 Deficiency Syndrome / 대한소아신경학회지

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%.