Severe myoclonic epilepsy of infancy (SMEI) or Dravet syndrome was described by Dr. Charlotte Dravet in 1978 as a severe epileptic syndrome.
It is one of the childhood epilepsy types that are more treatment resistant and is mainly characterized by the presence of prolonged febrile seizures during the first year of life and subsequent neurological deterioration.
It has also been described to patients that show some characteristic symptoms but lack other, which has been labeled as borderline SMEI or Dravet-like.
The genetic basis for some types of epilepsy has been widely demonstrated. In this pathology, most of the genes involved encode subunits of neuronal ion channels, so they are considered as "neural channelopathies” at a molecular level.
In Dravet syndrome, the major gene involved in causing the disease encodes the alpha 1 subunit of neuronal sodium channel (SCN1A). Mutations in this gene have been identified in 70% of cases. Recently (2009), associated mutations have also been described to the gene encoding protocadherin 19 (PCDH19) in approximately 10-20% of female patients with Dravet syndrome and SCN1A negative.
Currently, for the diagnostic of Dravet syndrome is recommended complete sequencing and MLPA of the 26 coding exons of the SCN1A gene. Depending on the clinical manifestations of each patient, the neurologist is the one who should propose the study of other genes such as GABRG2, SCN1B or PCDH19, or others as SCN5A, CDKL5, ARX, STXBP1 related with other channelopathies such as Brugada Syndrome, West Syndrome or Ohtahara Syndrome.
These genetic tests are aimed at patients with clinical suspicion of severe epilepsy in infancy, in order to genetically diagnose a patient and thus prescribe more accurate pharmacological treatments.
To perform these studies, it is necessary to obtain a blood sample from the patient. Send the blood sample or, if possible, the DNA extract to Secugen and approximately one month later Secugen will send you the diagnostic report describing the results obtained. Secugen provides specialized staff in your disposal to ensure consultations at any time.