Glucose transporter-1 (GLUT1) deficiency syndrome (GLUT1DS), also known as De Vivo disease, is a rare genetic metabolic condition characterized by infantile-onset epileptic encephalopathy, global developmental delay, drug-resistant seizures, progressive microcephaly, and movement disorders (e.g., spasticity, and dystonia) (GLUT1DS1; OMIM #606777) [1,2,3]. The gene discussed is SLC2A1; the disease is encephalopathy due to GLUT1 deficiency.