A quite different disorder of blood-brain barrier function is heterozygous mutation in the GLUT1/SLC2A1 gene, resulting in GLUT1-deficiency syndrome (GLUT1-DS), which manifests itself in infants as motor and mental developmental delay, seizures, reduced head growth and a movement disorder with ataxia, dystonia, and spasticity (Brockmann, 2009). The gene discussed is SLC2A1; the disease is Dravet syndrome.