Deficiencia del transportador de glucosa tipo 1: aspectos clínicos, diagnóstico y terapéutica / Glucose transporter type 1 deficiency syndrome: clinical aspects, diagnosis, and treatment

El síndrome de deficiencia del transportador de glucosa tipo 1 es una enfermedad de causa genética, que involucra el gen SLC2A1. En general, se presenta durante los primeros años de vida con retraso en la adquisición de pautas madurativas, epilepsia farmacorresistente y desórdenes del movimiento. La clínica y la disminución de glucosa en líquido cefalorraquídeo permiten sospechar el diagnóstico, el cual debe ser confirmado mediante el estudio molecular del gen SLC2A1. Debido a que se trata de una enfermedad poco frecuente y de expresión clínica variable, el diagnóstico precoz suele representar un desafío para los equipos de salud. Este es importante, ya que la implementación de la terapia cetogénica logra controlar las manifestaciones clínicas y mejora el pronóstico a largo plazo. Presentamos una revisión sobre el déficit del transportador de glucosa tipo 1, que abarca sus características clínicas, bioquímicas, moleculares y terapéuticas.

Glucose transporter type 1 deficiency with a typical onset is a genetic disorder associated with the SLC2A1 gene. Usually appears during the first years of life with severe developmental delay, drugresistant epilepsy, and movement disorders. Diagnosis is suspected based on clinical manifestations and a low glucose level in cerebrospinal fluid, and should be confirmed by the molecular genetic study of the SLC2A1 gene. As it is a rare disease with variable clinical expression, early diagnosis is often challenging for the healthcare team. Nevertheless, this is important because early implementation of ketogenic therapy will lead to control of the clinical manifestations and a better long-term prognosis. Here we review the glucose transporter type 1 deficiency syndrome focusing on its clinical, biochemical, molecular, and therapeutic characteristics.

A case of neonatal Kleefstra syndrome with SLC2A1 gene mutation / 中华实用儿科临床杂志

The clinical data of a newborn with Kleefstra syndrome combined with SLC2A1 gene mutation in the Department of Newborn Infants, Children′s Hospital of Nanjing Medical University were retrospectively analyzed.The laboratory examination, genetic characteristics, diagnosis and treatment progress were analyzed.This is the first report of a newborn with Kleefstra syndrome combined with SLC2A1 gene mutation, presenting with an early-onset epilepsy.Gene analysis is the most reliable method to make a definitive diagnosis.

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.

Associations between the HaeIII Single Nucleotide Polymorphism in the SLC2A1 Gene and Diabetic Nephropathy in Korean Patients with Type 2 Diabetes Mellitus

BACKGROUND: Diabetic nephropathy (DN) is the most serious microvascular complication of diabetes mellitus and is one of the leading causes of end stage renal failure. In previous studies, the contribution of genetic susceptibility to DN showed inconsistent results. In this study, we investigated the association between the solute carrier family 2 facilitated glucose transporter member 1 (SLC2A1) HaeIII polymorphism and DN in Korean patients with type 2 diabetes mellitus (T2DM) according to disease duration. METHODS: A total of 846 patients with T2DM (mean age, 61.3 ± 12.3 years; mean duration of T2DM, 10.3 ± 7.9 years; 55.3% men) who visited the Chungbuk National University Hospital were investigated. The HaeIII polymorphism of the SLC2A1 gene was determined by the real time polymerase chain reaction method. Genotyping results were presented as GG, AG, or AA. A subgroup analysis was performed according to duration of T2DM (≤ 10 years, < 10 years). RESULTS: The AG + AA genotype showed a significantly higher risk of DN compared with the GG genotype in patients with a type 2 DM duration less than 10 years (12.4% vs. 4.2%; P < 0.001). No significant differences were observed in terms of other diabetic complications, including retinopathy, peripheral neuropathy, cardiovascular disease, cerebrovascular disease or peripheral artery disease, according to the genotypes of the SLC2A1 HaeIII polymorphism. CONCLUSION: The SLC2A1 HaeIII polymorphism was associated with DN in Korean patients with T2DM, particularly in the group with a relatively short disease duration.

Paroxysmal Dyskinesia in Children: from Genes to the Clinic

BACKGROUND AND PURPOSE: Paroxysmal dyskinesia is a genetically and clinically heterogeneous movement disorder. Recent studies have shown that it exhibits both phenotype and genotype overlap with other paroxysmal disorders as well as clinical heterogeneity. We investigated the clinical and genetic characteristics of paroxysmal dyskinesia in children. METHODS: Fifty-five patients (16 from 14 families and 39 sporadic cases) were enrolled. We classified them into three phenotypes: paroxysmal kinesigenic dyskinesia (PKD), paroxysmal nonkinesigenic dyskinesia (PNKD), and paroxysmal exercise-induced dyskinesia (PED). We sequenced PRRT2, SLC2A1, and MR-1 in these patients and reviewed their medical records. RESULTS: Forty patients were categorized as PKD, 14 as PNKD, and 1 as PED. Thirty-eight (69.1%) patients were male, and their age at onset was 8.80±4.53 years (mean±SD). Dystonia was the most common symptom (38 patients, 69.1%). Pathogenic variants were identified in 20 patients (36.4%): 18 with PRRT2 and 2 with SLC2A1. All of the patients with PRRT2 mutations presented with PKD alone. The 2 patients carrying SLC2A1 mutations presented as PNKD and PED, and one of them was treated effectively with a ketogenic diet. Six mutations in PRRT2 (including 2 novel variants) were identified in 9 of the 13 tested families (69.2%) and in 8 patients of the 25 tested sporadic cases (32.0%). There were no significant differences in clinical features or drug response between the PRRT2-positive and PRRT2-negative PKD groups. CONCLUSIONS: This study has summarized the clinical and genetic heterogeneity of paroxysmal dyskinesia in children. We suggest that pediatric paroxysmal dyskinesia should not be diagnosed using clinical features alone, but by combining them with broader genetic testing.

Analysis of clinical and genetic features of one Chinese family with paroxysmal exercise-induced dyskinesia / 上海交通大学学报（医学版）

Objective· To study the clinical and genetic features of familial paroxysmal exercise-induced dyskinesia (PED) in a Chinese mainland family,and review the advances of clinical and genetic studies on PED.Methods· The clinical information of 7 family members in one Chinese pedigree,including 5 patients and 2 healthy people,was analyzed and the patients' response to treatment and prediction were followed up.The SLC2A1 gene in all 7 members of this family was sequenced.The clinical and genetic characteristics of 5 patients were analyzed.Advances of recent clinical and genetic studies related with PED were further reviewed.Results · Among the total 5 patients (male:female=1:4),four patients had pure form of PED,and one patient had PED plus epilepsy.Attacks of the proband and his daughter could not be well controlled by carbamazepine or sodium valproate.In addition,three patients showed a remission trend with age advancing.In this family,the SLC2A1 c.C284T (p.S95L) was identified in all 5 patients,but not in 2healthy members.According to the American College of Medical Genetics and Genomics (ACMG) criteria and guideline,the variant SLC2A1 c.C284T (p.S95L) was classified as pathogenic variant.Conclusion · PED is a rare paroxysmal movement disorder with highly phenorypic heterogeneity as well as a remission trend with age advancing.This paper reviews advances in clinical and genetic studies on PED recently,in order to contribute to the clinical diagnosis and appropriate treatment of PED.

The clinical feature of glucose transporter 1 deficiency syndrome and literature review / 中国小儿急救医学

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.

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.