Dravet syndrome, previously known as severe myoclonic epilepsy of infancy (SMEI), is an autosomal dominant genetic disorder which causes a catastrophic form of epilepsy, with prolonged seizures that are often triggered by hot temperatures or fever. It is very difficult to treat with anticonvulsant medications. It often begins before 1 year of age, with 6 months being the age that seizures, char­ac­ter­ized by prolonged convulsions and triggered by fever, usually begin. Signs and symptoms
Dravet syndrome has been characterized by prolonged febrile and non-febrile seizures within the first year of a childs life. This disease progresses to other seizure types like myoclonic and partial seizures, psychomotor delay, and ataxia. It is characterized by cognitive impairment, behavioural disorders, and motor deficits. Behavioural deficits often include hyperactivity and impulsiveness, and in more rare cases, autistic-like behaviours. Dravet syndrome is also associated with sleep disorders including somnolence and insomnia. The seizures experienced by people with Dravet syndrome become worse as the patient ages, as the disease is not very observable when symptoms first appear. This coupled with the range of severity differing between each individual diagnosed and the resistance of these seizures to drugs has made it challenging to develop treatments.Dravet syndrome appears during the first year of life, often beginning around six months of age with frequent febrile seizures (fever-related seizures). Children with Dravet syndrome typically experience a lagged development of language and motor skills, hyperactivity and sleep difficulties, chronic infection, growth and balance issues, and difficulty relating to others.
When the gene is mutated, the eventually translated protein improperly folds its pore segment within the cell membrane because it has different amino acid chemistry, which renders the channel inactive. It is also possible for a mutation to reduce the number of channels produced by an individual, which leads to the development of Dravet syndrome.Currently, the SCN1A gene is the most clinically relevant; the largest number of epilepsy related mutations characterized thus far occur in this gene. Typically, a missense mutation in either the S5 or S6 segment of the sodium channel pore results in a loss of channel function and the development of Dravet syndrome. A heterozygous inheritance of an SCN1A mutation is all that is necessary to develop a defective sodium channel; patients with Dravet syndrome will still have one normal copy of the gene. Diagnosis
According to the Dravet Syndrome Foundation, the diagnostic criteria for DS requires the patient to present with several of the following symptoms:
Onset of seizures in the first year of life in an otherwise healthy infant
Initial seizures are typically prolonged and are generalized or unilateral
Presence of other seizure types (i.e.