SLC2A1 and Intellectual disability: Because of his history of seizures with infantile onset, deceleration of head growth with microcephaly, ataxia, and moderate intellectual disability, a lumbar puncture was performed, which revealed a low CSF glucose concentration with a very low CSF-to-blood glucose ratio (< 0.4), and genetic tests detected a SLC2A1 gene exon 1 deletion confirming a diagnosis of GLUT1DS.