Clinical and genetic characteristics of glucose transporter type 1 deficiency syndrome

This article describes 4 clinical cases of glucose transporter type 1 deficiency syndrome (GLUT1, De Vivo disease) in children admitted to the neuropsychiatric department of Scientific and Practical Center of children medical care. The drug-resistant epilepsy, movement disorders, psychomotor and intellectual disabilities, decrease of glucose levels in the cerebrospinal fluid (CSF) were diagnosed in children. The different types of mutations in the SLC2A1 gene, responded for the development of GLUT1 deficiency syndrome were detected by targeted sequencing in all patients. De Vivo disease is characterized by the infantile-onset encephalopathy, symptomatic drug-resistant epilepsy, microcephaly, delayed psychomotor development with spasticity, ataxia, dysarthria and alternating hemiplegia and decrease the level of glucose in the CSF. Currently, the ketogenic diet is highly effective method of pathogenesis therapy, which can reduce the clinical manifestations: controlling the seizures, improving the movement disorder and speech.

Objective To investigate the clinical features of glucose transporter 1 deficiency syndrome(GLUT1-DS) and summarize the characteristics of GLUT1-DS through reviewing related references. Methods The clinical data including manifestation, cerebrospinal fluid(CSF) glucose, electroencephalogram, MRI and gene mutation of a patient with GLUT1-DS was collected and the related literatures were reviewed. Results The patient was a 6 years old boy.The patient, whose seizures occurred at the age of 9 month-old and prolonged to 6 year-old, attacked before breakfast.Physical examination showed microcephaly with head circumference 47.5 cm.Laboratory tests showed that CSF glucose decreased(1.87 mmol/L) and CSF-serum ratio was 0.36.And meantime the MRI was normal and electroencephalogram showed general spike and slow wave complex paroxysm.Mutation of SLC2A1 gene, c.350_385del, was found in the patient.There were 219 cases with GLUT1-DS had been reported and the age of onset was 15.69 months.In 219 patients, 159 cases(72%)suffered seizures, 105 cases(47%) had motor abnormalities, 61 cases(27%) suffered intellectual disability.The CSF glucose values were(1.92±0.31) mmol/L, CSF-serum ratio was 0.36±0.07.SLC2A1 gene mutations were detected in 183 patients(96%)in which missense mutation was the most mutation. Conclusion A wide range of phenotypes of GLUT1-DS include seizures, motor abnormalities, mental retardation.The diagnosis is confirmed when CSF glucose and CSF-serum ratio are continuously decreased which in the absence of meningitis.The SLC2A1 gene should be detected in suspicion of GLUTI-DS patients.Early diagnosis and treatment may improve the prognosis of those GLUTI-DS patients. Key words: Glucose transporter 1 deficiency syndrome; SLC2A1 gene; Seizures; Motor abnormalities

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. Key words: Glut 1 deficiency syndrome; Glucose transporter type 1; Brain diseases, metabolic; Diet therapy

Rationale:The SLC2A1 gene encodes glucose transporter 1 on blood–brain barrier, which plays an important role in the energy supply for neurons. Mutations in SLC2A1 gene can cause many clinical syndromes, including glucose transporter type 1 deficiency syndrome and many types of epilepsy syndromes such as childhood absence epilepsy and myoclonic-atonic epilepsy, etc. Ketogenic diet has been proved to be very effective on those cases. Clinically, SLC2A1 gene mutations are quite rare.Patient concerns:Repeated unconsciousness and bilateral limb weakness lasted for 3 years.Diagnoses:Myoclonic-atonic epilepsy.Lessons:After taking whole exome sequencing, we found out that there is a de novo insertion mutation in the patient's SLC2A1 gene, leading to frameshift. As a result, ketogenic diet (2:1, 4 times a day) was used as the treatment. As for the patient, total calories intake per day was controlled at 1190 kcal. The calories per kg per day were 66.11 kcal/kg. The amount of ketone bodies was controlled at 2 to 3 mmol/L and the concentration of plasma glucose was controlled at 4 to 5 mmol/L.Outcomes:After the launch of ketogenic diet, the patient has been seizure free for nearly a year and stopped all his antiepileptic drugs.Conclusion:Our case suggests that gene examination is very important part of the diagnosis of epilepsy etiology and epilepsy syndromes. Ketogenic diet should be considered as the first line therapy with SLC2A1 gene mutations.

Glucose transporter type 1 deficiency syndrome is a rare genetic disease that manifests neurological symptoms such as mental impairment or movement disorders, mostly seen in pediatric patients. Here, we highlight the main symptoms, diagnostic difficulties, and genetic correlations of this disease based on different clinical presentations between the members of a family carrying the same mutation. In this report, we studied siblings—a 5-year-old girl and a 6-year-old boy—who were admitted to a pediatric ward with various neurological symptoms. Different diagnostic procedures such as lumbar puncture, electroencephalography, and MRI of the brain were performed on these patients. Whole genome sequencing identified mutations in the SLC2A1 and GLUT1-DS genes, following which a ketogenic diet was implemented. This diet modification resulted in a good clinical response. Our case report reveals patients with the same genetic mutations having distinctive clinical manifestations.

Background:Glucose transporter type 1 deficiency syndrome is the result of impaired glucose transport into the brain. Patients with glucose transporter type 1 syndrome may present with infantile seizures, developmental delay, acquired microcephaly, spasticity and ataxia.Case Report:Here, we report a rare case of glucose transporter type 1 deficiency syndrome caused by a different pathogenic variant in a 10-day-old neonate who presented with intractable seizures and respiratory arrest.Conclusion:This new pathogenic variant can be seen in glucose transporter type 1 deficiency syndrome.

Le syndrome de déficit en transporteur du glucose de type 1 (GLUT-1)

On a three-dimensional templated model of GLUT1 (Protein Data Bank code 1SUK), a molecular recognition program, AUTODOCK 3, reveals nine hexose-binding clusters spanning the entire "hydrophilic" channel. Five of these cluster sites are within 3-5 A of 10 glucose transporter deficiency syndrome missense mutations. Another three sites are within 8 A of two other missense mutations. D-glucose binds to five sites in the external channel opening, with increasing affinity toward the pore center and then passes via a narrow channel into an internal vestibule containing four lower affinity sites. An external site, not adjacent to any mutation, also binding phloretin but recognizing neither D-fructose nor L-glucose, may be the main threading site for glucose uptake. Glucose exit from human erythrocytes is inhibited by quercetin (K(i) = 2.4 mum) but not anionic quercetin-semiquinone. Quercetin influx is retarded by extracellular D-glucose (50 mm) but not by phloretin and accelerated by intracellular D-glucose. Quercetin docking sites are absent from the external opening but fill the entire pore center. In the inner vestibule, Glu(254) and Lys(256) hydrogen-bond quercetin (K(i) approximately 10 microm) but not quercetin-semiquinone. Consistent with the kinetics, this site also binds D-glucose, so quercetin displacement by glucose could accelerate quercetin influx, whereas quercetin binding here will competitively inhibit glucose efflux. Beta-D-hexoses dock twice as frequently as their alpha-anomers to the 23 aromatic residues in the transport pathway, suggesting that endocyclic hexose hydrogens, as with maltosaccharides in maltoporins, form pi-bonds with aromatic rings and slide between sites instead of being translocated via a single alternating site.

Glucose transporter Type 1 (GLUT1) deficiency syndrome is a rare genetic disorder impairing glucose transport across the bloodbrain barrier, leading to reduced brain glucose availability and neurological symptoms, including epilepsy. The Ketogenic Diet (KD), high in fat and low in carbohydrates, induces ketosis, providing ketone bodies as an alternative brain fuel bypassing GLUT1 transport. This compensates for glucose deficiency, stabilising neuronal activity and reducing seizure frequency in GLUT1 deficiency. This case is of a 10-year-old girl with GLUT1 deficiency syndrome, developmental delay, SLC2A1 gene mutation and refractory epilepsy with 2-3 weekly seizures despite multiple Antiseizure Medications (ASMs). A South Indian-style KD, using traditional household ingredients, was initiated as medical nutrition therapy. Remarkable improvements were observed, a 50% reduction in seizures within one month, 80% reduction by three months and complete seizure freedom by the fourth month. Developmental progress accompanied seizure control and the diet was well-tolerated, maintaining stable nutritional status. This case highlights the efficacy of a culturally tailored KD in managing GLUT1 deficiency, emphasising its potential as a form of therapeutic treatment. Ongoing parental support and supervision were critical for ensuring dietary adherence and optimising outcomes.

Modified Atkins diet therapy for a case with glucose transporter type 1 deficiency syndrome

BackgroundGLUT1 Deficiency Syndrome 1 (GLUT1DS1) is a neurological disorder caused by either heterozygous or homozygous mutations in the Solute Carrier Family 2, Member 1 (SLC2A1) gene. SLC2A1 encodes Glucose transporter type 1 (GLUT1) protein, which is the primary glucose transporter at the blood–brain barrier. A ketogenic diet (KD) provides an alternative fuel for brain metabolism to treat impaired glucose transport. By reanalyzing exome data, we identified a de novo heterozygous SLC2A1 variant in a girl with epilepsy. After reversed phenotyping with neurometabolic tests, she was diagnosed with GLUT1DS1 and started on a KD. The patient's symptoms responded to the diet. Here, we report a patient with GLUT1DS1 with a novel SLC2A1 mutation. She also has a hemangioma which has not been reported in association with this syndrome before.Case presentationA 5-year 8-month girl with global developmental delay, spasticity, intellectual disability, dysarthric speech, abnormal eye movements, and hemangioma. The electroencephalography (EEG) result revealed that she had epilepsy. Magnetic resonance imaging (MRI) showed that non-specific white matter abnormalities. Whole Exome Sequencing (WES) was previously performed, but the case remained unsolved. The re-analysis of WES data revealed a heterozygous splicing variant in the SLC2A1 gene. Segregation analysis with parental DNA samples indicated that the variant occurred de novo. Lumbar puncture (LP) confirmed the diagnosis, and the patient started on a KD. Her seizures responded to the KD. She has been seizure-free since shortly after the initiation of the diet. She also had decreased involuntary movements, her speech became more understandable, and her vocabulary increased after the diet.ConclusionsWe identified a novel de novo variant in the SLC2A1 gene in a patient who previously had a negative WES result. The patient has been diagnosed with GLUT1DS1. The syndrome is a treatable condition, but the differential diagnosis is not an easy process due to showing a wide range of phenotypic spectrum and the overlapping symptoms with other neurological diseases. The diagnosis necessitates a genomic testing approach. Our findings also highlight the importance of re-analysis to undiagnosed cases after initial WES to reveal disease-causing variants.

Glucose transporter type 1 (GLUT1) deficiency syndrome (DS) is a metabolic brain disorder caused by a deficiency resulting from SLC2A1 gene mutation and is characterized by abnormal brain metabolism and associated metabolic encephalopathy. Reduced glucose supply to the brain leads to brain damage, resulting in delayed neurodevelopment in infancy and symptoms such as eye abnormalities, microcephaly, ataxia, and rigidity. Treatment options for GLUT1 DS include ketogenic diet (KD), pharmacotherapy, and rehabilitation therapy. Of these, KD is an essential and the most important treatment method as it promotes brain neurodevelopment by generating ketone bodies to produce energy. This case is a focused study on intensive KD nutritional intervention for an infant diagnosed with GLUT1 DS at Gangnam Severance Hospital from May 2022 to January 2023. During the initial hospitalization, nutritional intervention was performed to address poor intake via the use of concentrated formula and an attempt was made to introduce complementary feeding. After the second hospitalization and diagnosis of GLUT1 DS, positive effects on the infant's growth and development, nutritional status, and seizure control were achieved with minimal side effects by implementing KD nutritional intervention and adjusting the type and dosage of anticonvulsant medications. In conclusion, for patients with GLUT1 DS, it is important to implement a KD with an appropriate ratio of ketogenic to nonketogenic components to supply adequate energy. Furthermore, individualized and intensive nutritional management is necessary to improve growth, development, and nutritional status.

Objective: To explore the clinical characteristics of pediatric glucose transporter type 1 deficiency syndrome (GLUT1 DS), evaluate the efficacy and safety of ketogenic diet therapy (KDT). Methods: Clinical data of 19 children with GLUT1 DS admitted to Children's Hospital of Fudan University, Tianjin Children's Hospital, Shenzhen Children's Hospital, Children's Hospital of Nanjing Medical University and Jiangxi Provincial Children's Hospital between 2015 and 2019 were collected retrospectively. The first onset symptom, main clinical manifestations, cerebrospinal fluid features and genetic testing results of patients were summarized, the efficacy and safety of ketogenic diet treatment were analyzed. Results: Among the 19 cases, 13 were males and 6 females. The age of onset was 11.0 (1.5-45.0) months,the age of diagnosis was 54.0 (2.8-132.0) months. Epilepsy was the first onset symptom of 13 cases. Different forms of tonic-clonic seizures were the most common types of epilepsy (7 cases with generalized tonic-clonic seizures, 5 cases with focal tonic or clonic seizures, 4 cases with generalized tonic seizures). Antiepileptic drugs were effective in 4 cases. Paroxysmal motor dysfunction was present in 12 cases and ataxia was the most common one. All patients had different degrees of psychomotor retardation. Among 17 patients received cerebrospinal fluid examination, cerebrospinal fluid (CSF) glucose level was lower than 2.2 mmol/L and CSF glucose/glycemic index was<0.45 in 16 cases, only 1 case presented normal CSF glucose level (2.3 mmol/L) and normal CSF glucose/glycemic index(0.47). SLC2A1 gene mutations were found in 16 patients, missense, frameshift and nonsense mutations were the common types with 5 cases, 5 cases and 3 cases respectively. All 19 patients were treated with ketogenic diet, which was effective in 18 cases in seizure control, 11 cases in dyskinesia improvement and 18 cases in cognitive function improvement. No serious side effects were reported in any stage of KDT. Conclusions: The diagnosis of GLUT1 DS is often late. It is necessary to improve the early recognition of the disease and perform CSF glucose detection and genetic testing as early as possible. The KDT is an effective and safe treatment for GLUT1 DS, but a small number of patients have not response to diet therapy.

New Paradigm for the Treatment of Glucose Transporter 1 Deficiency Syndrome: Low Glycemic Index Diet and Modified High Amylopectin Cornstarch

Glucose transporter type I deficiency syndrome (GLUT1-DS) is the fourth most frequent single-gene epilepsy refractory to standard antiepileptic drugs. Multiple seizure types and variable electrographic findings are reported. Ketogenic diet is expected to result in the complete resolution of the epileptiform activity. A retrospective chart review of patients with GLUT1-DS on ketogenic diet between December 2012 and February 2022 was done. Analysis of the EEGs prior to and during the ketogenic diet was done. 34 patients on ketogenic diet were reviewed. Ten had clinical diagnosis of GLUT1-DS, and seven of them had genetic confirmation. 71% were female. The average age at seizure onset was 13.85 m.o. (range: 3-60, SD ±20.52), at diagnosis was 44.57 m.o (range: 19-79), and at the onset of ketogenic diet was 46.43 m.o. (range: 20-83). 29 months (range: 13-38) delay between symptoms onset until diagnosis was noticed. At the diagnosis 100% reported seizures: 71% myoclonic, 57% generalized motor, 57% absence, 28% atonic, and 14% focal motor. Also, 71% abnormal eye movements, 57% ataxia, and 28% intolerance to fasting. 86% had normal brain MRI. 71% had abnormal EEG. All were on ketogenic diet, and four on classical (1.75:1-2.25:1 ratio). Six were clinically seizure-free after the ketogenic diet. EEG features included notch delta, focal spike and wave, and generalized spike/polyspike and wave. One patient had bilateral independent centrotemporal spikes. Spikes showed high and very high amplitude in all of them (>200 μV). The variation of the spike index decreased in three patients but increased in two. Ketogenic diet is the choice treatment for patients with GLUT1-DS. Electrographic features could show worsening after initiation of the ketogenic diet even with seizure control. EEG did not prove to be a reliable tool for adjusting KD in our cohort. Centrotemporal spikes have not been reported in patients with GLUT-1 DS.