SLC2A1 mutations associated Glucose Transport Type 1 Deficiency Syndrome: A Single Center Case Series

Objectives Glucose transporter type 1 deficiency syndrome(GLUT1-DS) is usually due to the mutations of SLC2A1 gene and inherited in an OD pattern with 90 percent de novo mutation.Classic type(early-onset) is characterized by refractory infantile epilepsy,developmental delay,acquired microcephaly,and complex movement disorders.Non-classic phenotypes includes paroxysmal exercise-induced dyskinesia or choreathetosis and atypical absence or myoclonic astatic epilepsy. Methods The clinical and genetic findings of four consecutive patients with GLUT-1SD were retrospectively reviewed. Results The age range at diagnosis was 2.5-9.5 years.First and second case admitted with paroxysmal ataxia and dystonia without seizure as non-classic phenotype. The third case was admitted with refractory absence seizures and SLC2A1 gene was studied initially.However the fourth patient admitted with febrile seizures and continued with afebrile seizures with normal SCN1A-B gene and epileptic encephalopathy panels.When exercise-induced dyskinesia was observed in the clinical follow-up,the SLC2A1 gene was examined.The third and forth case were also non-clasic phenotype with epilepsy.Generalized epileptic anomaly was detected in the EEGs of three patients,and although third patient had multiple seizures,all EEG examinations were normal.All of the patients put on ketojenic diet.The SLC2A1 gene mutations were found to have De Novo in patient 1 and 3.Global developmental delay was observed in all of the patients. Conclusion All patients in our case series were in the non-classic phenotype and 3 of them diagnosed due to exercise-induced movement disorder.Children with unexplained epileptic seizures,developmental delay,and complex movement disorders with or withouth combination should be examined for GLUT1-DS.