Dravet syndrome is a rare, severe, and lifelong form of drug-resistant epilepsy. The first signs of the condition in otherwise healthy infants appear as frequent fever-associated seizures, but they progress quickly to different and more severe seizure types -- from brief absence seizures to full-blown tonic-clonic convulsive seizures. Longer seizures may evolve into status epilepticus, a life-threatening medical emergency where seizures are continuous. Dravet syndrome was previously known as severe myoclonic epilepsy of infancy (SMEI).
Dravet syndrome is suspected when an infant has more than two very long (10 minutes or more) seizures within the first year of life, when seizures occur on just one side of the body, or when an infant’s seizures are triggered by a warm water bath.
It's estimated that around 5% of children who experience a seizure in their first year may have Dravet, but it is commonly undiagnosed. 80% of children with Dravet have a mutated SCN1A gene, which causes sodium channels in the brain to malfunction (not all children with SCN1A develop Dravet; many have milder seizure disorders.) Other gene mutations that affect sodium channels also cause Dravet syndrome. The condition is usually the result of a new gene mutation (i.e., not passed from parents to children), and genetic testing may reveal the presence of the syndrome. Sequencing of the SCN1A gene is done to reveal the mutation that causes Dravet syndrome; however, the syndrome may also be caused by mutations in genes that have yet to be identified. Approximately 5%-10% of cases are caused by genetic material passed from parents to children.
Children with Dravet syndrome often experience sleep and nutrition disorders, chronic infections, and orthopedic conditions. Co-occurring disorders are common, such as autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), or dysautonomia, which impairs the body’s ability to regulate involuntary functions such as heating, cooling, and digestion.