In the April 15, 2013 early view issue of the journal Epilepsia, Doctors Hirose and colleagues from the Genetics Commission of the International League Against Epilepsy present an important, clinically applicable practice guideline with regards to SCN1A testing for epilepsy.
SCN1A is a gene that encodes for the alpha 1 subunit of neuronal voltage-gated sodium channels. Mutations in this gene are found in
- Dravet Syndrome
- febrile seizures plus (GEFS+), migrating partial seizures of infancy, and
- other infantile epileptic encephalopathies,
- and rarely in infantile spasms.
The Commission recommends testing:
- People with suspected Dravet Syndromes and may consider testing where the typical initial presentation is of a developmentally normal infant presenting with recurrent febrile or afebrile prolonged hemi-clonic seizures or generalized status epilepticus, and
- early onset infantile epileptic encephalopathies, such as migrating partial seizures of infancy.
This test is not recommended for:
- Children with phenotypes that are not clearly associated with the SCN1A mutations, such as those characterized by abnormal development or neurological deficits apparent at birth.
Interpreting test results means:
- Interpretation of the test results must always be done in the context of an electroclinical syndrome and requires the assistance of a medical geneticist.
- A negative test does not exclude a pathogenic role of SCN1A in a specific phenotype.
by Joseph I. Sirven, MD