SCN1A mutations are associated with a spectrum of seizure-related disorders, ranging from a relatively mild form of febrile seizures to a more severe epileptic encephalopathy known as Dravet syndrome.
Stiripentol, known to increase GABA<sub>A</sub> receptor activity as well as the metabolites of GABA<sub>A</sub> receptor agonists, is often used in the treatment of an epileptic encephalopathy, Dravet syndrome (DS), which is caused by mutations mainly in SCN1A and in other genes such as GABRG2.
We identified mutations in CDKL5, SCN2A, SETD5, ALG13, and TBL1XR1 in seven patients with West syndrome, and in SCN1A and GRIN1 in the two patients with unclassified epileptic encephalopathy.
Among these transmissions were two likely disease-causing mutations: an SCN1A mutation transmitted to an SUDC proband and her sibling with Dravet syndrome, as well as an SLC6A1 mutation in a proband with epileptic encephalopathy.
We present the clinical data of four patients (aged 8-21 years) with childhood-onset neurogenetic disorders, including ataxia-telangiectasia, Coffin-Lowry syndrome and epileptic encephalopathy due to SCN1A mutations.
This case demonstrates that SCN1A mutations may cause movement disorders as an atypical phenotype and the case history of this patient may expand our understanding of the clinical spectrum of SCN1A-associated epileptic encephalopathy.[Published with video sequences].
Dravet syndrome is a childhood disorder associated with loss-of-function mutations in SCN1A and is characterized by frequent seizures and severe cognitive impairment, thus well illustrating the concept of epileptic encephalopathy.
Recent descriptions of Rasmussen syndrome and of the hemiconvulsion-hemiplegia syndrome in isolated patients with SCN1A mutations are of uncertain meaning but might indicate that co-occurring immunomediated or seizure-induced structural changes can, in turn, become a substrate for the severe epileptic encephalopathy.