Phenotypic diversity of GLUT1 deficiency: A case report.

Objectives: A genetic defect in the SLC2A1 gene causes glucose transporter type 1 (GLUT1) deficiency syndrome, characterized by early infantile seizures, developmental delay, psychiatric disorders, microcephaly, ataxia, and various paroxysmal neurological symptoms. We present a case with infrequent, self-remitted, infantile-onset seizures experiencing new-onset ataxia and subtle attention-deficit symptoms. Case report: A 61/2-year-old girl from a non-consanguineous family of Turkish origin was admitted to the hospital due to fatigue and gait disturbance noticed, when tired or hungry, during the last year. Her blood glucose level, incidentally controlled two hours after a meal was 47mg/dL. She had developed generalized tonic-clonic seizures at the age of six months, had valproic acid treatment for three years and had not been on medication for 11/2 years. Clinical examination showed ataxic tandem gait, dysmetria, mild speech impediment and signs of a mild attention-deficit disorder. The cranial and spinal MRIs and echocardiography were unremarkable. Electroencephalography showed bilateral anterior sharp-slow wave activity predominantly on the right. A gene panel for epileptic encephalopathies unravelled a heterozygous, pathogenic variant in the SLC2A1 (NM_006516.4:c.680-11G>A). Further analysis of cerebrospinal fluid (CSF) in fasting state revealed hypoglycorrhachia (35 mg/dL), and the CSF-to-blood-glucose ratio was 0.41 with normal lactate levels. A ketogenic diet was started with the diagnosis of GLUT1 Deficiency Syndrome. Conclusion: Further genetic testing in early infantile epilepsy is critical for possible therapeutic interventions, not only for seizure control, but also for prevention of impairment of cognition or speech or behavioral disorder.
Keywords: Glucose Transporter Type 1, Epilepsy, Ataxia, Cerebrospinal Fluid, Ketogenic Diet