Introduction

Glucose transporter-1 (GLUT1) deficiency syndrome is caused by heterozygous mutations in the SLC2A1 gene, resulting in impaired glucose transport into the brain and hypoglycorrhachia. The clinical spectrum is wide, but it is classically characterized by treatment-resistant epilepsy, developmental delay and complex movement disorders.

Case Description

The patient was born at term from normal pregnancy and delivery. She was consulted repeatedly by child neurologist due to delayed psychomotor development, central hypotonia, ataxia and seizures. Seizures started at the age of 10mo and at 1y 4mo she had had 3 generalized tonic-clonic seizures and 3 eye-rolling episodes. All interictal electroencephalograms were normal and she was treated with levetiracetam. Magnetic resonance imaging, at 10mo and 1y 5mo, showed changes in white matter signal, indicating to delayed myelination. Full metabolic work-up was negative, except elevated plasma alanine, suggestive of possible mitochondrial disorder. At 1y 5mo muscle biopsy was performed and mitochondrial disorders were excluded. At the age of 2y 1mo cerebrospinal fluid (CSF) analysis showed low CSF glucose (2.0 mmol/l; normal range 3.3-4.4 mmol/l) and decreased CSF-to-blood glucose ratio (0.358) in the absence of hypoglycemia. Sequence analysis of SLC2A1 revealed a heterozygous mutation (c.968_972del p.V323Afs*56) and GLUT1 deficiency syndrome was diagnosed at the age of 2y 1mo. Treatment with ketogenic diet was started immediately with favourable response.

Conclusion

This is the first case of GLUT1 deficiency syndrome in Estonia. Recognizing GLUT1 deficiency syndrome is important, since it is effectively treated by ketogenic diet.

The study was supported by the EuroEPINOMICS grant SARLA 11091E.