There is now a blood test that can diagnose a rare neurometabolic condition known as Glut1 deficiency syndrome, or De Vivo disease. Glut1 deficiency syndrome is caused by a mutation in a gene called SLC2A1. Them mutation leads to a dysfunction in GLUT1, a glucose transporter that moves glucose into glial cells in the brain; the resulting lack of glucose can lead to developmental delays, abnormal movements or seizures. While Glut1 deficiency syndrome is rare, it is also treatable, so the researchers are recommending that any child who presents with symptoms should be tested. The findings have been reported in Neurology.
Glut1 deficiency syndrome is estimated to affect about one in 24,000 people, although that may be an undercount because patients who do not have epilepsy and have nonspecific symptoms may be much more difficult to diagnose. Testing used to involve a lumbar puncture as well.
The expensive, invasive, and typically lengthy procedure significantly limited its application, noted principal study investigator Professor Fanny Mochel. "Patients who are not diagnosed suffer a regrettable loss of opportunity. They could be treated. There is an urgent need to identify them better since many are missing or diagnosed too late."
Patients can be treated with a high-fat or ketogenic diet, which helps the body manage the loss of glucose in glial cells.
The GLUT1 transporter can be found on other cell types, including red blood cells. This test measures the level of GLUT1 on the surface of these cells with a cell-sorting technique called flow cytometry. A patient only has to provide a blood sample, and the results are available within 72 hours.
The new test is called METAglut1. In the validation study, 549 people who potentially had Glut1 deficiency syndrome and 87 patients in which the disorder had already been diagnosed were recruited. The test was found to have a sensitivity of about 80 percent, specificity over 99 percent, and high predictive value, which was comparable to results from the reference test. METAglut1 identifies 80 percent of patients with the syndrome at an early symptomatic stage.
Now clinicians can quickly test for the disease if it's suspected, and if the result is positive, treatment could be immediately started. This may significantly improve outcomes, particularly for children whose brains are still developing, noted Mochel.
All children with abnormal movements, epilepsy, intellectual disability, or neurodevelopmental disorders, should be tested, the researchers suggested.
Sources: Paris Brain Institute, Neurology
