also known as Glucose Transporter Type 1 Deficiency Syndrome, G1D, Glut1 DS, De Vivo Disease a rare genetic metabolic disorder characterized by deficiency of a protein (Glut1) that is required for glucose (a simple sugar and the primary energy source) to cross the blood-brain barrier. The resulting brain energy crisis can create a spectrum of symptoms including seizures, complex movement disorders, speech and language disorders, and developmental delays.
Aberrant Gaze Saccades rapid, repetitive, multidirectional eye movements often accompanied by a head movement in the same direction. These events sometimes occur in very young Glut1 Deficienty patients and resemble opsoclonus or nystagmus. video 1video 2video 3video 4video 5
Attention Deficit Hyperactivity Disorder (ADHD) a combination of problems that may include difficulty sustaining attention or focus, hyperactivity, and impulsive behavior.
Blood Brain Barrier a filtering and protective mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances.
Beta-hydroxybutyrate an energy-rich ketone body derived from fat which can be utilized by tissues and cross the blood-brain barrier during periods of glucose deficiency. It can be measured in blood and urine.
Confusion an altered state of consciousness characterized by inability to engage in orderly thought or by lack of power to distinguish, choose, or act decisively.
Developmental Delay not reaching cognitive or physical developmental milestones at the expected time.
Dysphagia difficulty swallowing, taking more time and effort to move food or liquid from mouth to stomach.
Epilepsy a medical condition with recurring seizures.
Episodic sporadic, havingsymptom-freeperiodsthatalternatewiththepresence of symptoms.
Genetic Disorder an inheritable medical condition caused by a DNA abnormality.
Autosomal Dominant a pattern of inheritance where only one copy (from one parent) of the abnormal gene is necessary for the disorder or trait to develop. Glut1 Deficiency is autosomal dominant.
Autosomal Recessive a pattern of inheritance where two copies (from both parents) of an abnormal gene must be present in order for the disorder or trait to develop.
De Novo Mutation an alteration in a gene that is present for the first time in one family member as a result of an error in the copying of genetic material or an error in cell division.
Congenital a condition existing at or before birth.
Gene the fundamental unit of heredity; a specific section of DNA within a chromosome.
Gene Sequencing analysis of a DNA sample to determine makeup and to look for deletions or mutations.
Genetic Mutation a permanent change in the DNA sequence such that the sequence differs from what is found in most people.
Genome an organism’s complete set of DNA, including all of its genes.
Genotype an individual’s collection of genes and genetic identity.
Phenotype the observable physical characteristics of an individual.
SLC2A1 gene: solute carrier family 2 (facilitated glucose transporter), member 1 provides instructions for producing a protein called the glucose transporter protein type 1 (GLUT1). The GLUT1 protein is embedded in the outer membrane surrounding cells, where it transports a simple sugar called glucose into cells from the blood or from other cells for use as fuel.
Hemiplegia weakness or paralysis on one side of the body, sometimes alternating sides. video 1video 2
Hemolytic Anemia abnormally increased breakdown of red blood cells.
Ketogenic Diet a high-fat, adequate-protein, low-carbohydrate dietary therapy that causes the body to burn fat for energy in the absence of glucose and is the recommended treatment for Glut1 Deficiency.
Ketones substances that are made when the body breaks down fat for energy or fuel as opposed to glucose. Ketone bodies produced are acetone, acetoacetate, and beta-hydroxybutyrate.
Ketosis a metabolic process that occurs when the body does not have enough glucose for energy. Fats are broken down for energy, resulting in the production of acids called ketones within the body.
Learning Disability neurologically-based problems that affect the brain’s ability to receive, process, analyze, or store information. Learning disabilities can interfere with learning basic skills such as reading, writing and/or math and with higher level skills such as organization, time planning, abstract reasoning, long or short term memory and attention.
Lethargy reduced level of consciousness marked by listlessness, drowsiness, and apathy.
Low Tone (hypotonia) a state of low muscle tone often accompanied by reduced muscle strength. Muscles may seem “floppy”, joints may seem loose or overly flexible, and poor posture, coordination, balance, and body awareness can result.
Lumbar Puncture (spinal tap) a procedure to collect and analyze the fluid (cerebrospinal fluid, or CSF) surrounding the brain and spinal cord. During a lumbar puncture, a needle is carefully inserted into the spinal canal low in the back (lumbar area) and samples of spinal fluid are collected.
Modified Atkins Diet (MAD) a ketogenic dietary therapy that is less restrictive than the classical ketogenic diet.
MCT oil (medium chain triglycerides) fatty acids composed of 6 – 12 carbon atoms. Oils can contain short chain, medium chain, or long chain fatty acids. Most oils are a combination of all three types. Medium chain oils are thought to be more ketogenic.
Migraines complex headaches that are usually characterized by severe pain on one or both sides of the head, an upset stomach, and, at times, disturbed vision.
Microcephaly a neurological condition that occurs when the head circumference is smaller than normal, associated with impaired brain growth and development.
Movement Disorders neurological conditions that affect the speed, fluency, quality, and ease of movement. video 1
Ataxia difficulty in coordinating movements; can include gait abnormality. Ataxia implies dysfunction of the portion of the nervous system that controls movement. video 1video 2video 3
Athetosis a symptom characterized by slow, involuntary, convoluted, writhing movements of the fingers, hands, toes, and feet. In some cases it can affect the arms, legs, neck and tongue.
Ballismus Repetitive, persistent, random, involuntaryflinging movements, usually involving the limbs.
Chorea abnormal involuntary movements. These are characterized by brief, irregular contractions that are not repetitive or rhythmic, but appear to flow from one muscle to the next and can occur at rest or when awake. video 1video 2video 3
Dyskinesia a category of movement disorders that are characterized by involuntary muscle movements.
Dystonia uncontrollable and sometimes painful muscle spasms caused by incorrect signals from the brain. It can affect the entire body or isolated parts of the body.
Myoclonus sudden, rapid, brief, involuntary jerking or spasm of a muscle or group of muscles. video 1
Paroxysmal Exercise Induced Dyskinesia (PED) dyskinesias (involuntary muscle movements) induced by prolonged exercise or physical exertion.
Spasticity abnormal tensing of the muscles that can cause stiffness or tightness of the muscles and can interfere with normal movement, speech, and gait.
Tremor an involuntary trembling or shaking movement, often rhythmic, in one or more body parts.
Paroxysmal a sudden attack, recurrence, or intensification of a disease.
Seizure sudden disruption of normal brain electrical activity and cell communication. Recurrent seizures are known as epilepsy. video 1
Absence seizure brief loss of consciousness (staring episode). video 1video 2
Atonic seizure a sudden and brief loss of muscle tone (also known as akinetic or drop attack).
Clonic seizure repetitive, rhythmic jerking movements of the body, often on both sides and in the arms and legs.
Focal or partial seizure seizures that begin and are confined to limited and specific areas of the brain, consciousness may or may not be affected.
Generalized seizure seizures that appear to start in all parts of the brain simultaneously and have no identifiable onset, consciousness is altered.
Myoclonic seizure sudden, rapid, brief, involuntary jerking or spasm of a muscle or group of muscles. video 1video 2
Tonic seizure tone is greatly increased and the body, arms, or legs make sudden stiffening movements.
Tonic-clonic seizure a convulsive seizure that begins with muscle tensing and tightening and loss of consciousness followed by jerking movements in the arms and legs.
Speech Disorders conditions that cause problems creating or forming the speech sounds needed to communicate with others.
Aphasia an impairment of language, affecting the production or comprehension of speech and the ability to read or write.
Apraxia a speech disorder where messages from the brain to the mouth are disrupted, and the lips or tongue are unable to be moved to the right place to say sounds correctly, even though the muscles are not weak.
Alogia complete lack of speech.
Disfluency impairment of the ability to produce smooth, fluent speech.
Dysarthria difficult or unclear articulation of speech that is otherwise linguistically normal. video 1
Triheptanoin or C7 oil a medium chain triglyceride oil (a fat) uniquely composed of an odd-numbered fatty acid chain. Triheptanoin is currently under investigation as a therapy for Glut1 Deficiency.