Understanding Genetic Epilepsy with Febrile Seizures Plus (GEFS+)

Watching your child have a seizure is one of the most frightening experiences a parent can face. It is natural to feel a sense of panic or to fear the worst. However, if your doctor has mentioned Genetic Epilepsy with Febrile Seizures Plus (GEFS+), it is important to understand that this is not a single disease with a single outcome. Instead, GEFS+ is a broad clinical spectrum of seizure disorders that often runs in families ^[1][2].

While the name sounds complex, each part tells us something specific:

• Genetic: It is often caused by changes in certain genes (most commonly SCN1A) that affect how the brain’s electrical signals are regulated ^[3].
• Epilepsy: It involves a tendency to have repeated seizures.
• Febrile Seizures: Seizures triggered by a high temperature or fever.
• Plus: This refers to seizures that go beyond the “typical” pattern of childhood febrile seizures ^[4].

Defining the ‘Plus’ in GEFS+

Most parents are familiar with typical childhood febrile seizures, which affect roughly 2% to 6% of all children ^[5]. These usually occur between the ages of 6 months and 5 years, are brief, and children almost always outgrow simple febrile seizures without any long-term issues.

However, an ordinary febrile seizure does not by itself mean a child has GEFS+. In GEFS+, the “plus” means the pattern is different. A child in a family with this spectrum might ^[4][6]:

• Continue having febrile seizures past the age of 6.
• Have seizures that occur even when they do not have a fever (afebrile seizures).
• Experience different types of seizures, such as absence seizures (staring spells) or myoclonic seizures (brief muscle jerks).

A Spectrum of Possibilities

Doctors call GEFS+ a “familial spectrum” because the symptoms can vary wildly even within the same family. Because it is often inherited in an autosomal dominant pattern, a parent may pass the gene change to their child. However, due to variable expressivity, the gene change doesn’t affect everyone the same way ^[7][8].

In a single family, you might see ^[9][10]:

• One relative who only had a few simple febrile seizures as a toddler and then outgrew them.
• Another relative (like your child) who has Febrile Seizures Plus (seizures continuing into later childhood).
• A relative who has a form of epilepsy that is well-controlled with medication.
• A relative who carries the gene change but never has a single seizure in their life—a concept called incomplete penetrance ^[1][8].

Overlapping Genetic Phenotypes

Because genes like SCN1A are involved in GEFS+, parents often worry about a more severe, related condition called Dravet syndrome. It is important to know that GEFS+ and Dravet syndrome are distinct clinical diagnoses. GEFS+ does not ordinarily “progress” into Dravet syndrome ^[11][12].

Most children with GEFS+ maintain normal development, and their seizures are often well-controlled or outgrown ^[13]. Dravet syndrome, on the other hand, is a developmental and epileptic encephalopathy characterized by frequent, prolonged seizures and significant developmental challenges ^[14]. Your doctor will carefully look at the age your child’s seizures started, the types of seizures they have, and their developmental progress to distinguish between these overlapping genetic conditions.

Why the Name Changed

You may occasionally see the term “Generalized Epilepsy with Febrile Seizures Plus.” However, the International League Against Epilepsy (ILAE) and researchers now prefer Genetic Epilepsy with Febrile Seizures Plus. This change happened because we discovered that the spectrum is not limited to generalized seizures (which affect the whole brain). Some people in these families have focal seizures (starting in one specific area), so the word “genetic” more accurately reflects the suspected cause without limiting the description of the seizures themselves ^[9].

Understanding that GEFS+ is a family-based spectrum can be a source of reassurance. By looking at the history of other family members, doctors can often get a better sense of a child’s likely path, though every child’s journey is unique ^[15].