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Generalized epilepsy with febrile seizures plus, type 9(GEFSP9)

MedGen UID:
863832
Concept ID:
C4015395
Disease or Syndrome
Synonyms: GEFS+, TYPE 9; GEFSP9
 
Gene (location): STX1B (16p11.2)
 
Monarch Initiative: MONDO:0014517
OMIM®: 616172

Definition

Generalized epilepsy with febrile seizures plus-9 is an autosomal dominant neurologic disorder characterized by onset of febrile and/or afebrile seizures in early childhood, usually before age 3 years. Seizure types are variable and include generalized tonic-clonic, atonic, myoclonic, complex partial, and absence. Most patients have remission of seizures later in childhood with no residual neurologic deficits, but rare patients may show mild developmental delay or mild intellectual disabilities (summary by Schubert et al., 2014). For a general phenotypic description and a discussion of genetic heterogeneity of GEFS+, see 604233. [from OMIM]

Additional description

From MedlinePlus Genetics
Genetic epilepsy with febrile seizures plus (GEFS+) is a spectrum of seizure disorders of varying severity. GEFS+ is usually diagnosed in families whose members have a combination of febrile seizures, which are triggered by a high fever, and recurrent seizures (epilepsy) of other types, including seizures that are not related to fevers (afebrile seizures). The additional seizure types usually involve both sides of the brain (generalized seizures); however, seizures that involve only one side of the brain (partial seizures) occur in some affected individuals. The most common types of seizure in people with GEFS+ include myoclonic seizures, which cause involuntary muscle twitches; atonic seizures, which involve sudden episodes of weak muscle tone; and absence seizures, which cause loss of consciousness for short periods that appear as staring spells.

The most common and mildest feature of the GEFS+ spectrum is simple febrile seizures, which begin in infancy and usually stop by age 5. When the febrile seizures continue after age 5 or other types of seizure develop, the condition is called febrile seizures plus (FS+). Seizures in FS+ usually end in early adolescence.

A condition called Dravet syndrome (also known as severe myoclonic epilepsy of infancy or SMEI) is often considered part of the GEFS+ spectrum and is the most severe disorder in this group. Affected infants typically have prolonged seizures lasting several minutes (status epilepticus), which are triggered by fever. Other seizure types, including afebrile seizures, begin in early childhood. These types can include myoclonic or absence seizures. In Dravet syndrome, these seizures are difficult to control with medication, and they can worsen over time. A decline in brain function is also common in Dravet syndrome. Affected individuals usually develop normally in the first year of life, but then development stalls, and some affected children lose already-acquired skills (developmental regression). Many people with Dravet syndrome have difficulty coordinating movements (ataxia) and intellectual disability.

Some people with GEFS+ have seizure disorders of intermediate severity that may not fit into the classical diagnosis of simple febrile seizures, FS+, or Dravet syndrome.

Family members with GEFS+ may have different combinations of febrile seizures and epilepsy. For example, one affected family member may have only febrile seizures, while another also has myoclonic epilepsy. While GEFS+ is usually diagnosed in families, it can occur in individuals with no history of the condition in their family.  https://medlineplus.gov/genetics/condition/genetic-epilepsy-with-febrile-seizures-plus

Clinical features

From HPO
Febrile seizure (within the age range of 3 months to 6 years)
MedGen UID:
3232
Concept ID:
C0009952
Disease or Syndrome
A febrile seizure is any type of seizure (most often a generalized tonic-clonic seizure) occurring with fever (at least 38 degrees Celsius) but in the absence of central nervous system infection, severe metabolic disturbance or other alternative precipitant in children between the ages of 3 months and 6 years.
Focal impaired awareness seizure
MedGen UID:
543022
Concept ID:
C0270834
Disease or Syndrome
Focal impaired awareness seizure (or focal seizure with impaired or lost awareness) is a type of focal-onset seizure characterized by some degree (which may be partial) of impairment of the person's awareness of themselves or their surroundings at any point during the seizure.
Tonic seizure
MedGen UID:
82855
Concept ID:
C0270844
Disease or Syndrome
A tonic seizure is a type of motor seizure characterized by unilateral or bilateral limb stiffening or elevation, often with neck stiffening.
Atonic seizure
MedGen UID:
78735
Concept ID:
C0270846
Disease or Syndrome
Atonic seizure is a type of motor seizure characterized by a sudden loss or diminution of muscle tone without apparent preceding myoclonic or tonic event lasting about 1 to 2 seconds, involving head, trunk, jaw, or limb musculature.
Delayed speech and language development
MedGen UID:
105318
Concept ID:
C0454644
Finding
A degree of language development that is significantly below the norm for a child of a specified age.
Bilateral tonic-clonic seizure
MedGen UID:
141670
Concept ID:
C0494475
Sign or Symptom
A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Generalized non-motor (absence) seizure
MedGen UID:
1385688
Concept ID:
C4316903
Disease or Syndrome
A generalized non-motor (absence) seizure is a type of a type of dialeptic seizure that is of electrographically generalized onset. It is a generalized seizure characterized by an interruption of activities, a blank stare, and usually the person will be unresponsive when spoken to. Any ictal motor phenomena are minor in comparison to these non-motor features.

Recent clinical studies

Etiology

Riza AL, Streață I, Roza E, Budișteanu M, Iliescu C, Burloiu C, Dobrescu MA, Dorobanțu S, Dragoș A, Grigorescu A, Tătaru T, Ioana M, Teleanu R
Genes (Basel) 2022 Jul 15;13(7) doi: 10.3390/genes13071253. PMID: 35886038Free PMC Article

Diagnosis

Riza AL, Streață I, Roza E, Budișteanu M, Iliescu C, Burloiu C, Dobrescu MA, Dorobanțu S, Dragoș A, Grigorescu A, Tătaru T, Ioana M, Teleanu R
Genes (Basel) 2022 Jul 15;13(7) doi: 10.3390/genes13071253. PMID: 35886038Free PMC Article
Marini C, Scheffer IE, Nabbout R, Mei D, Cox K, Dibbens LM, McMahon JM, Iona X, Carpintero RS, Elia M, Cilio MR, Specchio N, Giordano L, Striano P, Gennaro E, Cross JH, Kivity S, Neufeld MY, Afawi Z, Andermann E, Keene D, Dulac O, Zara F, Berkovic SF, Guerrini R, Mulley JC
Epilepsia 2009 Jul;50(7):1670-8. Epub 2009 Mar 12 doi: 10.1111/j.1528-1167.2009.02013.x. PMID: 19400878

Clinical prediction guides

Petruccelli E, Lansdon P, Kitamoto T
PLoS One 2015;10(9):e0137758. Epub 2015 Sep 11 doi: 10.1371/journal.pone.0137758. PMID: 26361221Free PMC Article
Nakayama J, Hamano K, Iwasaki N, Nakahara S, Horigome Y, Saitoh H, Aoki T, Maki T, Kikuchi M, Migita T, Ohto T, Yokouchi Y, Tanaka R, Hasegawa M, Matsui A, Hamaguchi H, Arinami T
Hum Mol Genet 2000 Jan 1;9(1):87-91. doi: 10.1093/hmg/9.1.87. PMID: 10587582

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