Dravet Syndrome is an epileptic encephalopathy that occurs in otherwise healthy infants. The seizures are usually caused by changes in body temperature (e.g., fever), closing of the eyes, light stimulation, exertion, fatigue, and infection. However, seizures may also occur without specific triggers.
The causes are mostly mutations in the SCN1A gene on chromosome 2, which codes for a voltage-gated sodium channel. As a result, there is a disruption of information transfer between neurons, which leads to epileptic seizures.
DS is inherited in an autosomal dominant trait, but most of the cases are caused by de novo mutations. Men are twice as likely to be affected as women. The first time seizures occur in the first year of life; these are tonic-clonic (Grand Mal) and often affect only one side of the body.
During a seizure, the side of the body affected may change, often ending seizures in a status epilepticus. Later, myoclonus and absences additionally occur. The frequency of seizures decreases with age. From the second year of life, there is usually a slower mental development, which manifests in psychomotor retardation, speech disorders and autistic behavior or hyperactivity.
Between the second and the fourth year of life, there is an increased risk of sudden infant death syndrome. Due to a difficult therapy as well as the developmental delays, the long-term prognosis is unfavorable, although 85% of those affected reach adulthood.