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Dravet syndrome, also known as severe myoclonic epilepsy of infancy (SMEI), is a rare form of epilepsy that begins in infancy. It is a debilitating, life-long condition that can severely impair the quality of life of the patient.
Patients experience frequent seizures, poor seizure control and developmental delays. Initial seizures are most often prolonged events when your child becomes feverish and in the second year of life other seizure types (often without fever) begin to emerge.
While a diagnosis of Dravet syndrome is made clinically, up to 80% of cases will also test positive for an SCN1A gene mutation, helping to confirm the diagnosis. It is important to note that the absence of an SCN1A mutation does not exclude diagnosis.
Genetic testing is commercially available in most countries. Upon receiving a positive genetic test result, parents may also be tested to establish inheritance.
Dravet syndrome occurs randomly; even though it is a genetic disease, the mutations are most often new mutations affecting only the child with the syndrome. In other words, the gene mutation is not present in other family members.
Signs and symptoms may include:
There are now commercially available blood tests which can screen for an SCN1A gene mutation that may be ordered by your doctor. However, current technology may not detect all mutations. Some screening labs also test for SCN2A, GABRG2 and PCDH19 mutations that may cause Dravet syndrome and related epilepsies. Consultation with a genetic counselor is available for families through some labs.
Children’s Hospital Colorado follows the largest group of children with Dravet syndrome in the region; and therefore our providers have experience with this rare syndrome. We have compassionate use access to stiripentol (an anticonvulsant drug used in the treatment of epilepsy; approved for the treatment of Dravet syndrome, as well as participate in national trials for treatment of this rare disorder.
This is a simple blood test that can be drawn in the lab. The results can take up to three months to return.
Dravet syndrome is diagnosed clinically based on seizure history, clinical aspects, neurologic examination, EEG pattern and observation. Subsequently, genetic testing of the SCN1A gene can confirm the diagnosis in the majority of cases. However, a mutated SCN1A gene cannot be identified in approximately 20% of the patients who meet the diagnostic criteria of the syndrome. Therefore, it is possible that other genes might be involved.
Because Dravet syndrome is a spectrum disorder, the course of the disease is variable from child to child and there is no standard treatment protocol. Multiple and changing seizure types are common and vary from patient to patient. EEG monitoring and neuroimaging techniques are often used to help further confirm diagnosis.
Anticonvulsants that have been shown to be useful for chronic seizure management in Dravet syndrome include benzodiazepines, topirimate and valproic acid. Stiripentol (Diacomit) has been shown to have efficacy in some Dravet patients when used in conjunction with other anticonvulsants, typically valproic acid and clobazam.