GLUT1 deficiency syndrome true Editor note: todo http://identifiers.org/hgnc/11005 The predominant seizure type in this metabolic disorder is absence seizures; myoclonic seizures and focal seizures are also seen. Around 10% of patients with early onset absence seizures and 5% of patients with epilepsy with myoclonic-atonic seizures have GLUT1 deficiency. A strong clue is the presence of paroxysmal exercise-induced dyskinesia in family members (or in the affected individual), which may be worse in the morning or after a period of fasting and relieved by carbohydrate. The ketogenic diet is the treatment of choice for GLUT1 deficiency and may result in seizure control and potentially improve cognitive outcome. Diagnosis may be suspected if a reduced CSF-blood glucose ratio (< 0.46) is found. The diagnosis can be confirmed by looking for reduced glucose transport across the erythrocyte membrane (which carries the same glucose transporter), and by mutation analysis of the solute carrier family 2, facilitated glucose transporter member 1 (SLC2A1) gene. MONDO:0000188 DC:0000690 OMIMPS:606777 metabolic etiology