What Is Dravet Syndrome and Why Is It Hard to Treat?
Dravet syndrome is a rare, catastrophic form of epilepsy that begins in infancy, resists most standard medications, and is caused by a single faulty gene. Here is how it works and why scientists are finally closing in on a cure.
A Catastrophic Epilepsy That Strikes in the First Year of Life
Most parents first notice something is wrong when their infant has a prolonged seizure — often triggered by a slight fever — before the age of six months. That moment frequently marks the beginning of a lifelong battle with Dravet syndrome, one of the most severe and treatment-resistant forms of childhood epilepsy known to medicine.
Once called Severe Myoclonic Epilepsy of Infancy, Dravet syndrome affects roughly 1 in every 15,700 people, according to the Dravet Syndrome Foundation. It is classified as a developmental and epileptic encephalopathy — meaning it does not merely cause seizures, but actively disrupts how the brain develops over time.
The Genetic Root: One Gene, One Broken Channel
In approximately 80% of cases, Dravet syndrome is caused by a mutation in a single gene: SCN1A. This gene carries the blueprint for a sodium channel — a microscopic protein pore in brain cells that opens and closes to let electrically charged sodium ions flow in and out, generating the signals neurons use to communicate.
In Dravet patients, one copy of SCN1A is faulty. This is known as haploinsufficiency: having only one working copy of a gene instead of two means the brain produces roughly half the normal amount of functional sodium channels. That shortfall sounds modest, but its consequences are severe.
The channels most affected sit on GABAergic inhibitory neurons — the brain's "brake" cells that suppress runaway electrical activity. When these cells cannot fire properly, excitatory neurons go unchecked. The result is an overexcited brain that seizes easily, sometimes for minutes at a time, according to research published in Frontiers in Cellular Neuroscience.
In most cases the mutation is de novo — it arises spontaneously and is not inherited from either parent.
Why Standard Anti-Seizure Drugs Often Make Things Worse
Here lies one of the cruelest ironies of Dravet syndrome. A large class of common anti-epileptic medications — including carbamazepine, lamotrigine, and oxcarbazepine — work by blocking sodium channels. In most epilepsies, this quiets overactive neurons. In Dravet syndrome, it further disables the already-struggling inhibitory cells, making seizures more frequent and more dangerous.
Physicians managing Dravet syndrome must therefore work with a narrower toolkit. First-line options include sodium valproate and clobazam, sometimes combined with stiripentol in a triple-therapy approach. Since 2018, cannabidiol (Epidiolex) has been FDA-approved specifically for the condition, offering additional seizure control for some patients. The ketogenic diet — a high-fat, very low-carbohydrate regimen — can also help in select cases, according to the Epilepsy Foundation.
Despite these options, most patients continue to experience frequent seizures throughout their lives.
Beyond Seizures: The Full Burden of the Disease
Seizures are only part of the story. As children with Dravet syndrome grow older, intellectual disability — often moderate to severe — becomes apparent by school age. Many develop speech impairments, behavioral difficulties resembling ADHD or autism spectrum disorder, and an abnormal crouching gait during adolescence.
There is also a heightened risk of SUDEP (Sudden Unexpected Death in Epilepsy), which occurs at a significantly higher rate in Dravet patients than in the general epilepsy population, according to the National Organization for Rare Disorders.
A New Approach: Fixing the Gene's Output
Rather than suppressing seizures after they start, researchers are now targeting the underlying genetic defect. The most advanced candidate is zorevunersen, an antisense oligonucleotide (ASO) — a short synthetic strand of DNA-like molecules designed to alter how the SCN1A gene's instructions are processed.
In a healthy cell, some SCN1A transcripts are accidentally degraded before they can be translated into protein. Zorevunersen binds to the faulty splice site responsible for this waste, redirecting the cell to produce more functional sodium channel protein from the one working copy of the gene. In a Phase 1/2 trial published in the New England Journal of Medicine, the drug reduced convulsive seizure frequency by up to 91% in some patients, while also improving cognition and behavior scores.
A separate gene therapy approach — ETX101, from Encoded Therapeutics — aims to deliver a regulatory molecule directly into neurons to boost SCN1A activity, with early trial results showing meaningful developmental gains in young children treated before age two.
Neither therapy is yet approved, but both represent a fundamental shift: from managing a disease to potentially correcting its cause at the molecular level — a goal that seemed remote when Dravet syndrome was first described by French neurologist Charlotte Dravet in 1978.
