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Genetic link
MAE belongs to a large group
of idiopathic generalised epilepsies referred to as GEFS+
(Generalised Epilepsies with Febrile Seizures Plus). Disorders associated
with GEFS+ are inherited or genetic so there may be, but not always, a family
history of seizures. Most epilepsies in this group are usually outgrown in
childhood, relatively benign or easy to treat.
Within the GEFS+ spectrum, more severe and complex
syndromes can occur including MAE and Dravet's Syndrome (SMEI or Severe Myoclonic Epilepsy of
Infancy).
Some of the epilepsy types
associated within the wide GEFS+ spectrum include:
- febrile seizures (FS)
where seizures with fever or high temperature occur. FS
affect 3% of ALL children, commonly outgrown by the age of 6 with
low risk of epilepsy in later life.
- febrile seizures plus
(FS+)
where febrile seizures continue
beyond 6 years of age sometimes interspersed with
afebrile
seizures occur.
- FS+ and absence seizures
- FS+ and myoclonic
seizures
- FS+ and partial seizures
- Myoclonic-astatic
epilepsy (MAE or Doose Syndrome)
- Dravet's Syndrome (SMEI
or Severe Myoclonic Epilepsy
in Infancy)
Several genes responsible for epilepsy in the GEFS+ group have
already been identified. At present, this is largely research except in the case of SMEI
(Dravet's Syndrome) where
a diagnostic test to identify the gene SCN1A has been developed which
can help confirm clinical findings and lead to better management of the
disorder.
The genetics of MAE are still not fully understood. We know that it
is polygenic meaning more than one gene is responsible for the
disorder but we don't know how many genes. It is likely that mutations
(or defects) of several genes have a combined effect to result in
MAE. It is
expected that in years to come, the genes responsible for MAE will be
identified and this will help confirm a diagnosis, target medications
and treatments leading to better management and improved outcomes
for our children. One day it may even possible to switch off these
faulty genes.
To learn more about the role
of genetics in GEFS+, download an audio version of
Professor Ingrid Scheffer's iLecture:
Understanding childhood epilepsy: from bedside to bench and back
again (30 May 2006)
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