Glucose transporter type 1 (GLUT1) deficiency syndrome is characterized by an encephalopathy marked by childhood epilepsy that is refractory to treatment, deceleration of cranial growth leading to microcephaly, psychomotor retardation, spasticity, ataxia, dysarthria and other paroxysmal neurological phenomena often occurring before meals. Symptoms appear between the age of 1 and 4 months, following a normal birth and gestation. The prevalence is unknown. Diagnosis is based on the clinical picture and biochemical analysis of the cerebrospinal fluid (CSF). In the majority of cases the disease is associated with de novo mutations in the SLC2A1 gene. GLUT1 deficiency syndrome is transmitted as an autosomal dominant trait and in these cases the affected parent presents with a mild form of the disease.