Glucose transporter type I deficiency syndrome (GLUT-1 DS) disorders are rare genetic disorders related to how glucose travels from blood to brain. Glucose is a form of sugar that normally provides essential energy to the body’s tissues and organs.
Children with GLUT-1 DS lack the protein required to transport glucose from the blood to the brain (and the other tissues). This results in low glucose levels in the child’s brain. These low glucose levels can result in decreased supply of energy that can then result in seizures, developmental delays, learning disorders and abnormal movements.
GLUT-1 DS can look very different from child to child. Cases can also vary in severity. Some are more severe, while others are milder. Some people may have a GLUT-1 that partly works, while for others, it may not work at all. This difference in how well the GLUT-1 works impact the severity of the disorder.
GLUT-1 DS usually appears in the first months or years of life. However, some cases may go undiagnosed until later in life. Different symptoms can appear at different times:
- Early symptoms. In severe cases, symptoms appear earlier in life. Symptoms might include epilepsy and developmental delay.
- Later symptoms. Some symptoms appear later in life. This can include abnormal movements and learning disorders.
Parents of a child with GLUT-1 DS should speak with a neurologist.
GLUT-1 DS disorders are caused by mutations of the SLC2A1 gene. The mutations are usually inherited rather than the result of a new, random change to the gene. GLUT-1 DS can be inherited in two ways:
- Autosomal dominant. In this type of inheritance, a single copy of the mutated gene can cause signs of the disorder. The more common form of GLUT-1 DS is passed on through this type of inheritance.
- Autosomal recessive. In this type of inheritance, two copies of the mutated gene must be inherited to cause signs of the disorder. The less common form of GLUT-1 DS is passed on through this type of inheritance.
SIGNS AND SYMPTOMS
GLUT-1 DS can cause different symptoms in different children. The severity of the symptoms may differ depending on the degree of the mutation. The most common symptoms include:
GLUT-1 DS causes several types of seizures. These include:
- Generalized tonic-clonic seizures. Episodes of sudden tightening of the muscles followed by rhythmic jerking of the hands and legs.
- Absence seizures. Brief episodes of staring or a sudden pause in activity.
- Myoclonic seizures. Abnormal muscle jerks.
- Paroxysmal exercise induced dyskinesia. Episodes of abnormal movements triggered by exercise. This has been noted in some children.
Slow growth of head circumference
Low muscle tone
Also known as hypotonia.
Early diagnosis is crucial to the long-term outcomes of patients with these disorders.
A diagnosis of a GLUT-1 DS can be made based on a combination of:
- Health history
- Clinical features
- Blood and urine tests
- Lumbar puncture
- Electroencephalogram (EEG), which measures the electrical activity of the brain
- Brain imaging
- Genetic testing
Diagnosis is often confirmed with genetic testing. The genetic testing can identify a mutation in the SLC2A1 gene, which is associated with this disorder. Families of children with a diagnosis of GLUT-1 DS disorders should receive genetic counseling.
Unfortunately, there is no cure for this disorder currently available. Anti-seizure medications are usually ineffective and not recommended. However, at least one treatment option is available.
The ketogenic diet has been a mainstay in treating GLUT-1 DS. This diet is high in fats and protein but includes minimal or no carbohydrates. Energy for the body can come from burning fats and protein rather than from using the glucose that comes from carbohydrates. This is helpful because fats can enter the brain without a need for GLUT-1.
The ketogenic diet has been used to reduce seizures in many individuals with epilepsy. It can work in those with GLUT-1 DS as well. In children with GLUT-1 DS, this diet has also often led to improvements in:
- Mental alertness
The ketogenic diet needs to be monitored by a dietician. Periodic blood and urine tests are also needed. The diet is rigid, and it is important that it be strictly followed. Those on the diet may also benefit from supplements that can offer essential vitamins and minerals.
Those with GLUT-1 DS may experience the disorder in different ways. However, identifying the disorder early can lead to a better outlook.
Importance of Early Diagnosis
Outcomes are usually much better if GLUT-1 DS is treated early. The sooner the seizures can be reduced, the better. For instance, infants with a severe version of GLUT-1 DS might have severe epilepsy and developmental delays. Yet seizures can usually be reduced if they are treated with a ketogenic diet as soon as possible. Cognition and learning can even improve in response to this diet.
Changes Over Time
There are two disorders related to GLUT-1 DS:
- Early-onset childhood absence epilepsy
- Cerebral folate deficiency
Glut1 Deficiency Foundation
The Glut1 Deficiency Foundation is a nonprofit patient advocacy organization dedicated to bringing help and hope to the Glut1 Deficiency community through its mission of increased awareness, improved education, advocacy for patients and families, and support and funding for research. Any child’s parent or caregiver, or any individual (age 18 or over) with a diagnosis of (or suspicion of) Glut1 Deficiency Syndrome who lives anywhere in the world can enroll in the G1D Patient Registry.
Child Neurology Foundation (CNF) solicits resources from the community to be included on this webpage through an application process. CNF reserves the right to remove entities at any time if information is deemed inappropriate or inconsistent with the mission, vision, and values of CNF.
ClinicalTrials.gov for Glut1 Deficiency (birth to 17 years). These are clinical trials that are recruiting or will be recruiting. Updates are made daily, so you are encouraged to check back frequently.
ClinicalTrials.gov is a database of privately and publicly funded clinical studies conducted around the world. This is a resource provided by the U.S. National Library of Medicine (NLM), which is an institute within the National Institutes of Health (NIH). Listing a study does not mean it has been evaluated by the U.S. Federal Government. Please read the NLM disclaimer for details.
Before participating in a study, you are encouraged to talk to your health care provider and learn about the risks and potential benefits.
The Glut1 Deficiency Foundation shares the unique and inspiring glimpses of exceptional families and amazing children with Glut1 Deficiency syndrome. These stories provide solace to other families and enlightenment to the medical community. They all help to play an important role in raising awareness and spreading education.
The information in the CNF Child Neurology Disorder Directory is not intended to provide diagnosis, treatment, or medical advice and should not be considered a substitute for advice from a healthcare professional. Content provided is for informational purposes only. CNF is not responsible for actions taken based on the information included on this webpage. Please consult with a physician or other healthcare professional regarding any medical or health related diagnosis or treatment options.
Wang D, Pascual JM, De Vivo D. Glucose Transporter Type 1 Deficiency Syndrome. 2002 Jul 30 [Updated 2018 Mar 1]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1430
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 Sep 5;325(10):703-9. http://doi.org/10.1056/NEJM199109053251006. PMID: 1714544.