The researchers found that loss of Nav1.1 channels was sufficient to cause the epilepsy and premature death seen in Dravet syndrome.The timing of the first signs and symptoms in Dravet syndrome occur about the same time as normal childhood vaccinations, leading some to believe the vaccine was the cause. However, this is likely a non-specific response to fever, as vaccination often induces fever, and fever is known to be associated with seizures in persons with Dravet syndrome. Some of the patients who put forth vaccine injury claims from encephalopathy were later found, upon testing, to actually have Dravet syndrome. Genetics
The genotypic explanation of the disorder has been located on the specific voltage-gated sodium channel genes known as SCN1A and SCN2A. These genes are located on the long (q) arm of chromosome 2 at position 24.3 and code for the alpha subunit of the transmembrane sodium channel protein. A mutation in either of these two genes will cause an individual to develop dysfunctional sodium channels, which are crucial in the pathway for sending chemical signals in the brain, causing the phenotypic display of myoclonic epilepsy from the individual. A properly functioning channel would respond to a voltage difference across the membrane and form a pore through which only sodium ions can pass. The influx of sodium induces the generation of action potential by temporarily changing the charge of the cell.
The effects of this disorder do not diminish over time, and children diagnosed with Dravet syndrome require fully committed caretakers with tremendous patience and the ability to closely monitor them.Febrile seizures are divided into two categories known as simple and complex. A febrile seizure would be categorized as complex if it has occurred within 24 hours of another seizure or if it lasts longer than 15 minutes. A febrile seizure lasting less than 15 minutes would be considered simple. Sometimes modest hyperthermic stressors like physical exertion or a hot bath can provoke seizures in affected individuals. However, any seizure uninterrupted after 5 minutes, without a resumption of postictal (more normal; recovery-type; after-seizure) consciousness can lead to potentially fatal status epilepticus. Causes
In most cases the mutations in Dravet syndrome are not hereditary and the mutated gene is found for the first time in a single family member. In 70–90% of patients, Dravet syndrome is caused by nonsense mutations in the SCN1A gene resulting in a premature stop codon and thus a non-functional protein. This gene normally codes for neuronal voltage-gated sodium channel Nav1.1. In mouse models, these loss-of-function mutations have been observed to result in a decrease in sodium currents and impaired excitability of GABAergic interneurons of the hippocampus.