Glucose transporter 1 deficiency syndrome (GLUT1-DS) is due to heterozygous mutation of the
glucose transporter type 1 gene (GLUT1/SLC2A1). GLUT1-DS is characterized by
movement disorders, including
paroxysmal exercise-induced dystonia (PED), as well as
seizures,
mental retardation and hypoglycorrhachia.
Tremor was recently shown to be part of the phenotype, but its clinical and electrophysiological features have not yet been described in detail, and GLUT1
tremor reports are rare. We describe two patients, a young woman and her mother, who were referred to us for
tremor. We also systematically review published cases of GLUT1-DS with
tremor (14 cases, including ours), focusing on clinical features. In most cases (10/14), the
tremor, which involved the limbs and voice, fulfilled clinical criteria for dystonic
tremor (DT), occurring in body areas affected by
dystonia.
Tremor was the only permanent symptom in 2 cases. Recordings, reported here for the first time, showed an irregular 6- to 8.5-Hz
tremor compatible with DT in our two patients. These findings show that
tremor, and particularly DT, may be a presenting symptom of GLUT1-DS. Patients who present with dystonic
tremor, with or without
mental retardation,
seizures,
movement disorders and/or a family history, should therefore be screened for GLUT1-DS.