GLUT1 Deficiency Syndrome

What is GLUT1 DS?

GLUT1 deficiency syndrome (GLUT1 DS) refers to a spectrum of a genetic neurological disorders caused by the improper transport of glucose into the brain. Conditions falling on this spectrum go by many names and include many variants, such as: – Glut1 deficiency syndrome – G1D – De Vivo disease – Glucose Transporter protein syndrome – Glucose Transporter Type 1 deficiency syndrome – Dystonia 9 However, GLUT1 DS can be generalized under two “umbrellas:” common GLUT1 deficiency syndrome and non-epileptic GLUT1 deficiency syndrome.

1. Common GLUT1 deficiency syndrome is the most prevalent form of GLUT1 DS, and it affects 90% of those afflicted. It’s primarily characterized by seizures that begin soon after birth, but neurological symptoms vary; individuals often experience developmental delays, intellectual disabilities, and/or physical manifestations, like headaches and movement disorders.
2. Non-epileptic GLUT1 deficiency syndrome is typically less severe and less common; only about 10% of individuals with GLUT1 DS are included under this classification. While people with this form of GLUT DS may have developmental and intellectual delays, as well as noticeable movement difficulties, individuals will not experience epileptic episodes.

GLUT1 DS is incredibly rare; since its discovery, only about 500 cases have been documented worldwide, though it is most likely being underdiagnosed.

What causes GLUT1 DS?

GLUT1, or glucose transporter protein type 1, is responsible for transporting the simple sugar, glucose, from the blood and into cells of the body. Due to a mutation in the gene SLC2A1, which makes GLUT1, the protein becomes damaged and glucose does not make it past the blood-brain barrier. Like a car without fuel, the brain does not have the energy to function properly, resulting in GLUT1 DS.

What are the signs and symptoms of GLUT1 DS?

While symptoms and severity are different from person to person, GLUT1 DS can be characterized by varying types of seizures, as well as difficulties within three general categories: cognition, movement, and behavior.

1. Cognition: speech and language development, learning difficulties, intellectual disabilities, mental confusion, lethargy, etc.
2. Movement: involuntary spasms (spasticity), diminished muscle tone (hypotonia), muscle contractions, paralysis, etc.
3. Behavior: troubles with social adaptive behaviors, shortened attention span, etc.

How do people inherit GLUT1 DS?

GLUT1 DS either results from sudden mutations or the inheritance of at least one copy of the mutated gene in each cell. As such, cases of GLUT1 DS can occur in families where one or both parents are carriers (autosomal dominant pattern or autosomal recessive pattern), or within families with no history of the condition.

Where can I find more information about GLUT1 DS?

• GLUT1 Deficiency Foundation
• National Organization for Rare Disorders (NORD)
• U.S. National Library of Medicine