What does SCN1A stand for?
SCN1A (sodium voltage-gated channel alpha subunit 1) is a gene that provides instructions for making one part of a sodium channel called NaV1. 1. These channels control the flow of sodium into cells in the brain (neurons), which is necessary for electrical balance.
What causes SCN1A mutation?
While the majority of DS patients carry de novo SCN1A mutations, some cases have been described in which the mutation was inherited from an asymptomatic or mildly affected parent, suggesting that the expression of the mutation in the transmitting parent was modified by environmental and/or genetic factors or was the …
What is SCN1A epilepsy?
SCN1A seizure disorders encompass a spectrum that ranges from simple febrile seizures and generalized epilepsy with febrile seizures plus (GEFS+) at the mild end to Dravet syndrome and intractable childhood epilepsy with generalized tonic-clonic seizures (ICE-GTC) at the severe end.
Where is the SCN1A gene located?
chromosome 2q24
The SCN1A gene is located on the chromosome 2q24, composed of 26 exons spanning 6030 bp and encodes the large α-subunit of the voltage-gated sodium ion channel, type 1 (NaV 1.1)28 (see Figure 1).
What age does Dravet syndrome start?
Symptoms of Dravet syndrome Seizures, usually starting between the ages of 4 months and 12 months, are the first sign of Dravet syndrome. These first seizures often occur with a fever (called febrile seizures).
How is Dravet syndrome diagnosed?
Electroencephalogram (EEG) and magnetic resonance imaging (MRI) test results are often normal when seizures first appear, which can sometimes delay diagnosis. When Dravet syndrome is suspected, genetic testing may be done to look for a pathogenic variant in the SCN1A gene.
What mutation causes Dravet syndrome?
Dravet syndrome is associated with a mutation in the SCN1A gene in 80-90% of cases (Rosander 2015).
How many patients does dravet have?
Dravet syndrome affects an estimated 1:15,700 individuals in the U.S., or 0.0064% of the population (Wu 2015). Approximately 80-90% of those, or 1:20,900 individuals, have both an SCN1A mutation and a clinical diagnosis of DS. This represents an estimated 0.17% of all epilepsies.
What triggers Dravet syndrome?
In at least 80 percent of cases, Dravet syndrome is caused by defects in a gene required for the proper function of brain cells. Mutations in the SCN1A gene (a gene that encodes as a sodium channel, a part of the cell membrane involved in nervous system function) are the primary causes of Dravet syndrome.
Can you grow out of Dravet syndrome?
While there is no cure for Dravet syndrome, early diagnosis and treatment may minimize seizure frequency and intensity. Without treatment, individuals will continue to have frequent seizures and can suffer from seizure-related accidents or even mortality.
How does Dravet syndrome affect the brain?
Dravet syndrome genetics Genetic variants that affect the SCN1A sodium channel impair the flow of sodium ions into neurons in the brain and lead to overactivity of neurons. This overactivity causes seizures and epilepsy.
Is Dravet syndrome life limiting?
Dravet syndrome is a rare, severe, and lifelong form of epilepsy (seizure disorder). Most people affected by this condition have a good life expectancy. The disease typically starts in the first year of life, and around 80-85% of the children survive into adulthood.
What is the lifespan of a child with Dravet syndrome?
The average life expectancy of people with Dravet syndrome is not clear, but estimates suggest that 10–20% of individuals with Dravet syndrome do not survive beyond the age of 10. Sudden unexpected death in epilepsy (SUDEP) is the most common cause.
Can you outgrow Dravet syndrome?
However, as treatment methods improve along with the understanding of the disease, some researchers expect that long-term outcomes will improve. While there is no cure for Dravet syndrome, the genetic cause of most cases of the disease is known, which provides hope that researchers may find a way to address this cause.