Do Glut1 (glucose transporter type 1) defects exist in epilepsy patients responding to a ketogenic diet?

In the recent years, several neurological syndromes related to defects of the glucose transporter type 1 (Glut1) have been descried. They include the glucose transporter deficiency syndrome (Glut1-DS) as the most severe form, the paroxysmal exertion-induced dyskinesia (PED), a form of spastic paraparesis (CSE) as well as the childhood (CAE) and the early-onset absence epilepsy (EOAE). Glut1, encoded by the gene SLC2A1, is the most relevant glucose transporter in the brain. All Glut1 syndromes respond well to a ketogenic diet (KD) and most of the patients show a rapid seizure control. Ketogenic Diet developed to an established treatment for other forms of pharmaco-resistant epilepsies. Since we were interested in the question if those patients might have an underlying Glut1 defect, we sequenced SLC2A1 in a cohort of 28 patients with different forms of pharmaco-resistant epilepsies responding well to a KD. Unfortunately, we could not detect any mutations in SLC2A1. The exact action mechanisms of KD in pharmaco-resistant epilepsy are not well understood, but bypassing the Glut1 transporter seems not to play an important role.