Mutations in SLC2A1, which encodes the glucose transporter GLUT1, most commonly cause de vivo or GLUT1 deficiency syndrome (GLUT1 DS), characterized by infantile seizures, acquired microcephaly, developmental delay, and motor incoordination consisting of ataxia and dystonia (OMIM #606777). The gene discussed is SLC2A1; the disease is cerebellar ataxia.