Diagnosing your patients with Glut1 DS
Dr. Abbie Collins | Child Neurologist
Undiagnosed Glut1 DS may be the underlying cause of neurological problems
Symptoms of Glut1 DS are often misattributed to other causes. There is often a delay of several years between seizure onset and a Glut1 DS diagnosis. During that time, patients may not be getting treatment for the underlying cause of neurological problems. Because Glut1 DS has a spectrum of symptoms—some appearing later in childhood—controlling seizures should not be the only goal of treatment. That’s why an early and accurate diagnosis is important.1
Undiagnosed Glut1 DS may account for…
- 1% of idiopathic generalized epilepsy2
- 10% of early onset absence epilepsy3
- 8% of paroxysmal dyskinesia4
Cerebrospinal fluid (CSF) glucose concentrations provide a diagnostic clue to Glut1 DS5
Laboratory features most suggestive of Glut1 DS are:
- CSF glucose < 60 mg/dL
- CSF/blood glucose ratio < 0.4
- CSF lactate < 1.3 mmol/L
Genetic testing for Glut1 DS
Detection of heterozygous pathogenic variant (or rarely, biallelic pathogenic variants) in SLC2A1 helps confirm Glut1 DS. In rare instances the Glut1 DS diagnosis is not confirmed by genetic testing, even when the disease is confirmed by other means.5
Ultragenyx is sponsoring a program to make no-cost genetic testing for Glut1 DS available for patients with symptoms of Glut1 DS or a family history of the disease. Learn about ordering a no-cost test for Glut1 DS for one of your patients by clicking here.
The test does not identify a mutation in all people who have Glut1 DS. A negative test result does not necessarily mean that your patients do not have Glut1 DS.
Importance of genetic testing for Glut1 DS
Genetic testing can help confirm a diagnosis of Glut1 DS.6 An early, accurate diagnosis can help in:
- Focusing on treatments for the underlying cause of the disease
- Addressing the whole spectrum of Glut1 DS symptoms—not just seizures
- Help people with Glut1 DS and their families plan for their future
No-cost genetic testing
No-cost genetic testing for Glut1 DS is available for your patients.
- Test results take about 2 weeks
- Optional genetic counseling at no-cost is available
- Panel includes 3 key mutations which may account for up to 47% of paroxysmal dyskinesia cases7
– SLC2A1 for Glut1 DS
– PRRT2 for Paroxysmal Kinesigenic Dyskinesia (PKD)
– PNKD (MR-1) for Paroxysmal Nonkinesigenic Dyskinesia (PNKD)
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References: 1. Pong AW, Geary BR, Engelstad KM, Natarajan A, Yang H, De Vivo DC. Glucose transporter type 1 deficiency syndrome: epilepsy phenotypes and outcomes. Epilepsia. 2012;53(9):1503-1510. doi:10.1111/j.1528-1167.2012.03592.x. 2. De Giorgis V, Veggiotti P. Glut1 deficiency syndrome 2013: current state of the art. Seizure. 2013;22(10):803-811. doi:10.1016/j.seizure.2013.07.003. 3. Arsov T, Mullen SA, Damiano JA, et al. Early onset absence epilepsy: 1 in 10 cases is caused by Glut1 deficiency. Epilepsia. 2012;53(12):e204-e207. 4. Erro R, Sheerin U-M, Bhatia KP. Paroxysmal dyskinesias revisited: a review of 500 genetically proven cases and a new classification. Mov Disord. 2014;29(9):1108-1116. 5. Wang D, Pascual JM, De Vivo D. Glucose transporter type 1 deficiency syndrome. In: Pagon RA, Adam MP, Ardinger HH, et al, eds. GeneReviews® [Internet]. Seattle, WA: University of Washington, Seattle; 1993-2016. http://www.ncbi.nlm.nih.gov/books/NBK1430/. Published July 30, 2002. Updated January 22, 2015. 6. Pearson TS, Akman C, Hinton VJ, Engelstad K, De Vivo DC. Phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS). Curr Neurol Neurosci Rep. 2013;13(4):342-350. doi:10.1007/s11910-013-0342-7. 7. Gardiner AR, Jaffer F, Dale RC, et al. The clinical and genetic heterogeneity of paroxysmal dyskinesias. Brain. 2015;138(Pt 12):3567-3580. doi:10.1093/brain/awv310.