Glut1 deficiency syndrome is a lesser-known neurological disorder caused by a genetic mutation that restricts adequate glucose supply to the brain, resulting in symptoms like seizures, abnormal movement, and developmental delays. A new blood test, METAglut1, has been developed by scientists that can swiftly diagnose the disease, making the invasive lumbar puncture process redundant. This test holds a sensitivity of approximately 80% and a specificity exceeding 99%.
Despite the considerable negative impacts of Glut1 deficiency syndrome, it is largely unfamiliar to the healthcare industry. The disorder stems from an alteration in the SLC2A1 gene, leading to a dysfunctional glucose transporter, GLUT1, in the individuals affected. This transporter is crucial for enabling glucose absorption into glial cells; hence, its malfunction deprives the brain of the necessary glucose for optimal operation. Consequently, patients suffer from seizures, bouts of abnormal movements, and developmental setbacks.
Nonetheless, the detrimental symptoms can be alleviated through regulation of the metabolic anomaly that causes the disease, such as through a high-fat ketogenic diet. Additionally, potential therapeutic molecules designed to compensate for the inadequate glucose supply to brain cells are currently under assessment.
“Undiagnosed patients lose a significant opportunity for treatment,” comments Professor Fanny Mochel, the leading investigator of the study. “The necessity for better identification is urgent as many are either overlooked or diagnosed too late.”
The occurrence of Glut1 deficiency syndrome is speculated to be 1 in 24,000 in the general population, a likely underestimate given it only takes epileptic patients into account and ignores those with isolated, unspecific symptoms like learning disabilities or abnormal movements. The disease has been even more challenging to diagnose because it previously relied on a luminary puncture supported by genetic tests.
“This invasive, time-consuming, and costly method significantly restricts healthcare accessibility,” adds the researcher. “That’s why the pursuit of a blood biomarker that enables a rapid Glut1 deficiency syndrome diagnosis is crucial.”
Traces on Red Blood Cells Offer Insight
The GLUT1 transporter, which is highly abundant in the endothelial and glial cells of the brain, is also present on the surface of erythrocytes, or red blood cells. The diagnostic test developed by Paris-based biotech firm METAFORA biosystems quantifies GLUT1 on the surface of these cells via flow cytometry, a common laboratory analysis technique. The test requires just a simple blood sample and is not dependent on the patient fasting beforehand. The results are typically available within 48 to 72 hours.
To verify the efficacy of the new test, METAglut1, teams from AP-HP and 33 French clinical investigation centers, led by Professor Fanny Mochel, recruited 549 prospective patients (those suspected to have the disease) and 87 retrospective patients (those already diagnosed). The objective was to compare the effectiveness and precision of METAglut1 against the standard diagnostic test that necessitates cerebrospinal fluid sampling and genetic analysis.
The findings of the research team suggest that METAglut1 has a sensitivity of around 80%, a specificity of over 99%, and a high predictive value, equivalent to the standard test. “These figures formally validate the utility of the test,” asserts Professor Fanny Mochel. “This enables quicker and simpler screening for Glut1 deficiency syndrome in numerous patients. Upon a positive result, treatment can commence immediately, considerably enhancing the prognosis, particularly for children undergoing brain development.”
Therefore, the authors of the study recommend that the test be administered to all children older than three months, and adults with intellectual disability, neurodevelopmental disorders, abnormal movements, or epilepsy—particularly if it is drug-resistant and a ketogenic diet relieves the seizures. Indeed, if utilized at an early symptomatic stage, METAglut1 can instantly identify 80% of patients with Glut1 deficiency syndrome. Consequently, the French National Authority for Health endorses its reimbursement, paving the way for its uptake across Europe and the US.
Reference: “Prospective Multicenter Validation of a Simple Blood Test for the Diagnosis of Glut1 Deficiency Syndrome” by Fanny Mochel et al., for the MetaGlut1 Study Group, 19 April 2023, Neurology.
DOI: 10.1212/WNL.0000000000207296
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Frequently Asked Questions (FAQs) about Glut1 deficiency syndrome diagnosis
What is the Glut1 deficiency syndrome?
Glut1 deficiency syndrome is a lesser-known neurological disorder caused by a genetic mutation that restricts the adequate supply of glucose to the brain, leading to symptoms such as seizures, abnormal movement, and developmental delays.
What is the new blood test for diagnosing Glut1 deficiency syndrome?
The new blood test is called METAglut1. Developed by scientists, this test can swiftly diagnose Glut1 deficiency syndrome, making the invasive lumbar puncture process redundant. The test has a sensitivity of around 80% and a specificity exceeding 99%.
How does the METAglut1 test work?
The METAglut1 test quantifies the GLUT1 transporter on the surface of erythrocytes (red blood cells) via flow cytometry. It requires a simple blood sample and does not require the patient to fast. The results are typically available within 48 to 72 hours.
Who is recommended to take the METAglut1 test?
The test is recommended for all children older than three months and adults with intellectual disability, neurodevelopmental disorders, abnormal movements, or epilepsy, particularly if it is drug-resistant and a ketogenic diet relieves the seizures.
Is the METAglut1 test widely available?
The French National Authority for Health endorses the reimbursement of the METAglut1 test, which paves the way for its wider uptake across Europe and the United States.
More about Glut1 deficiency syndrome diagnosis
- Overview of Glut1 Deficiency Syndrome
- Genetic Home Reference – Glucose transporter type 1 deficiency syndrome
- Neurology – Prospective Multicenter Validation of a Simple Blood Test for the Diagnosis of Glut1 Deficiency Syndrome
- Information on METAglut1 Test
- Information about Lumbar Puncture
- Overview of Flow Cytometry
