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GLUT1 deficiency syndrome
This syndrome typically leads to a range of neurological problems due to impaired glucose transport into the brain. It often first presents in infancy or early childhood and can affect individuals differently.
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Overview
GLUT1 deficiency syndrome, also known as De Vivo disease, is a rare genetic disorder where the brain does not receive enough glucose. Glucose is the main sugar used by the brain for energy, and its transport into brain cells is crucial for normal function and development [PMID:33678567]. Without sufficient glucose, brain cells cannot function properly, leading to various neurological challenges.
This condition is often diagnosed in infancy or early childhood, though symptoms can vary in severity and presentation. It is important to understand that while daily management can help, GLUT1 deficiency syndrome is a lifelong condition that requires ongoing care.
Symptoms & clinical features
The symptoms of GLUT1 deficiency syndrome can vary widely among individuals but typically involve the nervous system. Common features often include epilepsy, which may manifest as different seizure types, and problems with movement, such as ataxia (lack of coordination) or spasticity (muscle stiffness) [PMID:33678567].
Developmental delays, particularly affecting motor skills and language, are also frequently observed. Some individuals may experience intellectual disability, though the severity can vary from mild to severe. Other possible symptoms can include head growth abnormalities (microcephaly), paroxysmal exercise-induced dyskinesia (involuntary movements triggered by physical activity), and speech difficulties.
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Affected organs
The primary organ affected by GLUT1 deficiency syndrome is the brain. The condition directly impacts the brain's ability to receive and utilise glucose, which is essential for its normal function and development. As a result, the symptoms seen in individuals with GLUT1 deficiency syndrome are primarily neurological. While other body systems are generally not directly affected by the glucose transport issue, the brain's impaired function can indirectly influence other areas, such as muscle control and overall physical development.
Risks & severity
The severity of GLUT1 deficiency syndrome can range significantly between individuals, even within the same family. Symptoms often appear in infancy or early childhood, although some forms, such as paroxysmal exercise-induced dyskinesia, might become noticeable later [PMID:33678567]. Complications can include difficult-to-control seizures and significant developmental delays. Early diagnosis and appropriate management are important for potentially improving outcomes and managing symptoms effectively.
The exact prevalence of GLUT1 deficiency syndrome is not well established, but it is considered a rare condition. While the condition is lifelong, research suggests that early intervention, particularly dietary management, can often lead to a reduction in seizure frequency and can support neurodevelopment [PMID:30138952].
Genetic causes
GLUT1 deficiency syndrome is caused by pathogenic variants in the SLC2A1 gene. This gene provides instructions for making a protein called glucose transporter type 1, or GLUT1. The GLUT1 protein is vital for transporting glucose from the bloodstream across the blood-brain barrier into the brain's cells.
Pathogenic variants in SLC2A1 reduce the amount of functional GLUT1 protein or alter its structure, making it less effective at transporting glucose. This leads to a deficiency of glucose in the brain, impairing its energy supply and resulting in the neurological symptoms characteristic of the syndrome. Understanding this genetic basis helps explain why the brain is primarily affected and why glucose is so critical for proper brain function.
- SLC2A1 solute carrier family 2 member 1
Inheritance pattern
GLUT1 deficiency syndrome is typically inherited in an autosomal dominant pattern. This means that a person only needs one altered copy of the SLC2A1 gene to develop the condition. In most cases, the pathogenic variant occurs spontaneously as a new change in the gene (a de novo variant) in the affected individual, meaning it was not inherited from either parent. However, it can also be inherited from an affected parent.
If a parent has GLUT1 deficiency syndrome, there is a 50% chance with each pregnancy that their child will also inherit the altered gene and develop the condition. Genetic counselling can provide more specific information and support for families concerned about inheritance patterns.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
Diagnosis & testing
Diagnosis of GLUT1 deficiency syndrome usually begins with a clinical suspicion based on the characteristic neurological symptoms, particularly when standard anti-seizure medications are not effective. A key diagnostic indicator can be low glucose levels in the cerebrospinal fluid (CSF) despite normal glucose levels in the blood, which is often assessed via a lumbar puncture [PMID:30138952].
Confirmation of the diagnosis involves genetic testing to identify pathogenic variants in the SLC2A1 gene. In the UK, such testing is available through the NHS Genomic Medicine Service (GMS). Referral for genetic testing would typically come from a neurologist or a paediatrician. Relevant R-codes for this diagnostic pathway allow for targeted sequencing of the SLC2A1 gene.
Management & lifestyle
Management of GLUT1 deficiency syndrome primarily focuses on providing an alternative fuel source for the brain. The ketogenic diet is the most common and effective treatment strategy [PMID:33678567]. This diet is very high in fat, moderate in protein, and very low in carbohydrates, which encourages the body to produce ketones from fat. Ketones can then be used by the brain for energy instead of glucose.
Treatment is supervised by a multidisciplinary team, including neurologists, dietitians, and genetic counsellors, to ensure the diet is safely initiated and maintained. Other supportive therapies may include anti-seizure medications to manage epilepsy, and physical, occupational, and speech therapy to address developmental delays and improve motor skills. Regular monitoring and adjustments to the management plan are often necessary as an individual grows and develops.
UK care pathway
In the UK, individuals suspected of having GLUT1 deficiency syndrome would typically be referred by their GP or existing specialist (e.g., paediatrician, neurologist) to a Clinical Genetics service. This service can provide expert evaluation and access to the NHS Genomic Medicine Service (GMS) for diagnostic genetic testing. The GMS uses specific R-codes to ensure the appropriate genetic investigations are performed, for example, targeted sequencing of the SLC2A1 gene. Genetic counsellors within these services play a crucial role in explaining the condition, its inheritance, and supporting families through diagnosis and beyond.
Frequently asked questions
What is the main problem in GLUT1 deficiency syndrome?
The main problem is that the brain cannot get enough glucose, its primary energy source. This happens because the protein responsible for transporting glucose into the brain, called GLUT1, is not working correctly.
Is there a cure for GLUT1 deficiency syndrome?
There is currently no cure for GLUT1 deficiency syndrome, but it can be managed effectively. The ketogenic diet is the primary treatment, providing an alternative fuel (ketones) for the brain and often significantly improving symptoms, especially seizures.
How is GLUT1 deficiency syndrome usually diagnosed?
Diagnosis often starts with observing typical symptoms, followed by tests such as a lumbar puncture to check glucose levels in the spinal fluid. Genetic testing of the SLC2A1 gene through the NHS Genomic Medicine Service confirms the diagnosis.
Can GLUT1 deficiency syndrome be inherited from parents?
It can be inherited, but often it occurs as a new genetic change in the child (de novo). If a parent has the condition, there is a 50% chance their child will also inherit it. Genetic counselling can provide personalised risk information.
References
- Klepper J, Akman C, Armeno M. Glut1 Deficiency Syndrome (Glut1DS): State of the art in 2020 and recommendations of the international Glut1DS study group. Epilepsia open. 2020. PMID: 32913944
- Klepper J. Glut1 Deficiency Syndrome: Novel Pathomechanisms, Current Concepts, and Challenges. Journal of inherited metabolic disease. 2025. PMID: 40405536
- Koepsell H. Glucose transporters in brain in health and disease. Pflugers Archiv : European journal of physiology. 2020. PMID: 32789766
- Deng D, Xu C, Sun P. Crystal structure of the human glucose transporter GLUT1. Nature. 2014. PMID: 24847886
- Gras D, Roze E, Caillet S. GLUT1 deficiency syndrome: an update. Revue neurologique. 2014. PMID: 24269118
- Klepper J, Leiendecker B. GLUT1 deficiency syndrome--2007 update. Developmental medicine and child neurology. 2007. PMID: 17718830
- Tang M, Monani UR. Glut1 deficiency syndrome: New and emerging insights into a prototypical brain energy failure disorder. Neuroscience insights. 2021. PMID: 34589708
- Taher M, Leen WG, Wevers RA. Lactate and its many faces. European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society. 2016. PMID: 26481417