Dravet syndrome (also known as severe myoclonic epilepsy of infancy) is a type of epilepsy characterized by episodes of prolonged seizures that begin in the first year of life. It is a rare condition that affects one in 20,000 to 40,000 people worldwide.
What causes Dravet syndrome?
Dravet syndrome is a genetic condition. In around 80%–90% of patients, the disease is caused by mutations in the SCN1A gene. In the remaining cases, the disease is thought to be the result of mutations in other genes, some of which have yet to be identified.
Most of the disease-causing mutations occur de novo, meaning that they are new and not passed on from the parents. But in up to 10% of the time, mutations causing Dravet syndrome are inherited from the parents in an autosomal dominant manner, meaning that only one faulty copy of the disease-causing gene is sufficient for the condition to develop.
How does Dravet syndrome affect the body?
Dravet syndrome is characterized by seizures that last longer than five to 30 minutes, or longer, and are difficult to control with anti-epilepsy medications. The seizures may be triggered by fever, illness, a warm bath, or warm weather, particularly in the early phases of the disease.
Symptoms of Dravet syndrome may range from sleeping disorders and behavioral problems to a higher risk of infections. Most children with Dravet syndrome experience developmental problems to some extent, such as cognitive impairment, and weakness in muscle coordination (or ataxia).
How is the disorder diagnosed?
A full clinical history of the patient is essential for the diagnosis of Dravet syndrome based on symptoms. Among the information gathered by clinicians is the time the seizures started, their frequency and duration, possible triggers of seizures, and the patient’s development.
Since children with Dravet syndrome may initially experience typical development, genetic testing is useful to diagnose the condition and consists of a simple blood test to detect if the patient has a mutation in the SCN1A gene or other epilepsy-related genes.
However, genetic testing alone is not always conclusive and should be interpreted in the context of other findings, as some SCN1A mutations can cause forms of epilepsy other than Dravet syndrome.
What is the appropriate care for patients?
Previous studies have shown that treatment with sodium valproate, topiramate, or clobazam may reduce seizures in Dravet syndrome patients. These medications can be combined to reduce seizure frequency more effectively.
Diacomit (stiripentol), an anticonvulsant medication, was approved in 2018 as an add-on therapy for seizures associated with Dravet syndrome. In the same year, Epidiolex, a cannabis derivative, was approved by the U.S. Food and Drug Administration (FDA) to treat the disorder.
More recently, Fintepla (fenfluramine) was approved in 2020 by the FDA for the treatment of seizures in patients with Dravet syndrome.
Additionally, a ketogenic diet — a restrictive diet low in carbohydrates, limited in protein, and high in fat — may be prescribed if anti-epileptic medicines do not help the patient sufficiently.
Research on developing new and more efficient treatments for Dravet syndrome is ongoing.
What’s the outlook for patients?
Dravet syndrome is a lifelong condition with serious implications on the quality of life of patients and their families.
Long and frequent seizures may have severe consequences, including sudden unexpected death in epilepsy, status epilepticus, and a higher risk of accidents such as drowning or injuries.
However, with regular care and supervision, the majority of children with Dravet syndrome have a normal life expectancy.