Researchers at the Children’s Hospital of Philadelphia (CHOP) have discovered a specific genetic variant in SCN1A, the most common genetic epilepsy, leading to an earlier onset of epilepsy, with clinical features different from other epilepsy. The researchers also identified a potentially effective treatment strategy. The findings were recently published in the journal Epilepsy.
Most genetic variants in SCN1A are associated with Dravet syndrome. Dravet syndrome is a form of genetic epilepsy characterized by seizures beginning in the first year of life, along with differences in child development and features of an autism spectrum disorder. In these cases, there is a loss of function variant of SCN1A, meaning that the resulting protein cannot perform its normal functions. However, this study focused on a gain-of-function variant of SCN1Ameaning the resulting protein performs additional functions in ways that can be harmful.
This genetic change does the exact opposite of what it should, which in turn causes a peculiar clinical picture. A better understanding of what this variant does is critical for us to determine which treatments to choose for affected patients.”
Ingo Helbig, MD, senior study author, pediatric neurologist in the Department of Neurology and co-director of the Epilepsy Neurogenetics Initiative (ENGIN) at CHOP
In this study, researchers used diagnostic testing to identify four patients with an identical gain-of-function variant in SCN1A. All four patients had early developmental epileptic encephalopathy (DEE), which is characterized by a combination of seizures and developmental delays. In these specific cases, patients experienced focal tonic seizures, which are seizures that cause stiffening of the body in a specific area, and other types of seizures that started in the first few weeks of life. The study also found that patients with this recurrent gain-of-function variant in SCN1A-related epilepsy had an earlier onset of their disease compared to patients with loss-of-function variants.
In addition, the study found that oxcarbazepine, a seizure control drug for children and adults, may help patients. One of the patients responded to treatment with the drug and the variant showed sensitivity to the drug.
“Our findings may provide an explanation for why we had previously identified some patients as having atypical Dravet syndrome, as the earlier onset of symptoms associated with this gain-of-function variant allows us to properly evaluate these cases. distinguishable,” said the first author of the study. Jérôme Clatot, PhD, director of the ENGIN Ion Channel/Electrophysiology Core at CHOP. “We hope to raise awareness of these and other potential gain-of-function variants, especially if common antiepileptic drugs can help them.”