GLUT1-DS in a Girl with Transitory Abnormal Eye Movements and Seizures Responding to Carbamazepine

Introduction: Diagnosing GLUT1 deficiency syndrome (GLUT1-DS) is sometimes challenging because of its broad clinical spectrum. The diagnosis may be delayed when the first manifestations are considered as less typical for the disease. It is usually assumed, for instance, that seizures will be resistant to conventional antiepileptic drugs. Other clinical manifestations, such as early-onset abnormal eye movements, are probably under-recognized as a suggestive feature.

Case Report/Methods: We report the findings of a baby who presented at 2 months with paroxysmal abnormal eye movements that progressively disappeared and were thought to be related to immaturity of the optic pathways. These were followed a few months later by the appearance of myoclonic, tonic–clonic, and tonic seizures as well as absences. Seizures rapidly and fully responded to low doses of carbamazepine. GLUT1-DS was diagnosed genetically at 2 years, after global developmental delay, ataxia, as well as short dystonic left hand movements had emerged. Molecular analysis identified a de novo heterozygous deletion -c.1033_1042del, p.(Ala345Profs*4)- on SLC2A1. Hypoglycorrhachia 1.5mmol/L was present. A ketogenic diet was started.

Discussion: A high level of suspicion is needed to diagnose GLUT1-DS. Early abnormal eye movements should be recognized as suggestive for the disease, even in the case of progressive remission. Our case also illustrates the fact that in GLUT-1 DS patients, seizures may respond favorably to classic antiepileptic drugs. This should by no means be considered as exclusive for the diagnosis.