Frequently asked questions (FAQs) about Glut1 DS

Glut1 DS stands for glucose transporter type-1 deficiency syndrome. It is a rare, genetic disease caused by a mutation or change in a gene called SLC2A1. In people with Glut1 DS, glucose—the brain’s primary energy source—is inhibited from crossing the blood-brain barrier. If the brain can’t get enough glucose, it becomes starved of energy, which can lead to a variety of symptoms experienced by people with Glut1 DS, including:

Seizures

Seizures may appear differently in each person, and not all people affected by Glut1 DS have seizures. Absence seizures, in which a person appears to lose awareness or stares into space for a short time (and does not respond), are common in Glut1 DS.

Movement disorders

People with Glut1 DS may experience abnormal limb movements such as twitching, flailing, writhing, and poor balance. These can be ongoing or occasional. Problems walking or running may be a sign of a movement disorder. Additionally, abnormal, involuntary eye movements that cannot be controlled have been found in people with Glut1 DS.

Developmental delays

Children affected by Glut1 DS may experience motor (movement) and developmental delays, including learning disabilities and language difficulties.

Learn more about the signs and symptoms of Glut1 DS.

About 90% of people with Glut1 DS are the first person in their family to have the disease. The disease typically arises from a new mutation in the gene associated with Glut1 DS. People with Glut1 DS have a 50% chance of passing the disease on to each child. Glut1 DS is inherited in an autosomal dominant pattern, which means that a person with one copy of the SLC2A1 gene mutation from either their mother or father will have the disease.
Glut1 DS is a rare disease that was first identified in 1991. It affects from 3000 to 7000 people in the United States. It is difficult to know the exact number because many people with Glut1 DS have not been correctly diagnosed.
No. There is a wide variety of symptoms caused by Glut1 DS, and some cases of Glut1 DS are more severe than others. It was once thought that people with Glut1 DS had 3 categories of symptoms—seizures, movement disorders, and developmental delays. We now know that many people with confirmed Glut1 DS have only 1 or 2 categories of symptoms.
The SLC2A1 gene tells the body to make glucose transporters. Glucose transporters are necessary to carry glucose—the brain’s primary energy source—across the blood-brain barrier to the brain. Without glucose transporters, glucose can’t get to brain cells that need energy to function, and the brain becomes starved for energy.
People with Glut1 DS may have symptoms that don’t respond to treatment as expected. When the doctor suspects Glut1 DS, there are tests that are often used to determine if Glut1 DS is the underlying cause. Before genetic testing, Glut1 DS was often confirmed by using a procedure called a lumbar puncture and comparing the amount of glucose in the cerebrospinal fluid to that in the bloodstream. Genetic testing, using a blood test, can help confirm a Glut1 DS diagnosis. The test may not identify a mutation in all people who have Glut1 DS. A negative test result does not necessarily mean you do not have Glut1 DS. The presence of the mutation helps identify Glut1 DS.* Learn about getting a no-cost genetic test for Glut1 DS.

*Even if a Glut1 DS diagnosis is not confirmed by testing, there is still a chance that you may have the disease.

Ask your doctor if he or she thinks genetic testing is appropriate for you or someone in your family. Learn about getting a no-cost genetic test for Glut1 DS.
If you or a family member has symptoms that might be caused by Glut1 DS, talk to your doctor about getting a diagnosis using genetic testing. Also, if someone in your family has been diagnosed with Glut1 DS, genetic testing can help identify other family members who may also have the
SLC2A1 gene mutation.
Learn about getting a no-cost genetic test for Glut1 DS.

There are currently no approved medicines for Glut1 DS, but there are treatments that may be helpful in managing symptoms. Consult your doctor about any potential Glut1 DS treatments. Learn more about caring for Glut1 DS.

If you or a family member is newly diagnosed with Glut1 DS, it’s understandable that you may want to connect with others. If so, click here to see a list of resources and independent patient advocacy groups.

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References: 1. US National Library of Medicine. Glut1 deficiency syndrome. http://ghr.nlm.nih.gov/condition/glut1-deficiency-syndrome. Updated March 2014. Accessed April 27, 2016. 2. 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. 3. 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. 4. 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. 5. De Vivo DC, Trifiletti RR, Jacobson RI, Ronen GM, Behmand RA, Harik SI. Defective glucose transport across the blood-brain barrier as a cause of persistent hypoglycorrhachia, seizures, and developmental delay. N Engl J Med. 1991;325(10):703-709. 6. Ultragenyx announces positive data from investigator-sponsored trial of triheptanoin in glucose transporter type-1 deficiency syndrome [news release]. Novato, CA: Ultragenyx Pharmaceutical Inc.; April 22, 2015. http://ir.ultragenyx.com/releasedetail.cfm?releaseid=907860. Accessed March 28, 2016.