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 disease is encephalopathy due to GLUT1 deficiency (Monarch Disease Ontology identifier MONDO_0011724). Also known as: De Vivo disease, GLUT1 deficiency syndrome 1, infantile onset, severe, GLUT1 deficiency syndrome type 1, GLUT1-DS, Glucose Transporter Type 1 Deficiency Syndrome, glucose transporter type 1 deficiency, glut-1 deficiency syndrome.