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Febrile Seizures Plus, Genetic Epilepsy With Febrile Seizures Plus

Etiologies: Febrile seizures plus and genetic epilepsy with febrile seizures plus are distinguished on the basis of family history. Most of them are related to gene mutations (such as SCN1A, SCN1B, GABRG2, GABRB3, SCN2A, PCDH19, GABRD, GABRB2, etc. Note that mutations in some of the above genes can also cause severe developmental and epileptic encephalopathy, which is related to different mutation sites and other factors). Some may also involve complex inheritance [1-8].

Age of onset: It usually starts with febrile seizures between the ages of 6 months and 6 years, which can continue past 6 years of age, but it is usually self limiting and resolve by puberty.

Seizure characteristics: Afebrile seizures (sporadic) may also occur. The mandatory seizures are generalized tonic clonic seizures (more common in classic cases, lasting about 3-6 minutes), while atonic seizures, myoclonic seizures, absence seizures or myoclonic-atonic seizures (but if this seizure type is dominant and without prominent febrile seizures, it may be more appropriate to diagnose epilepsy with myoclonic-atonic seizures (Doose syndrome)) may also occur. In addition, there may be focal seizures (frontal or temporal origin is common). If the duration of febrile seizures is significantly prolonged or hemiclonic seizures occur, the possibility of Dravet Syndrome should also be considered [9-10].

EEG: Background: normal. Interictal: it can be normal, and some of them can show 4-7Hz theta rhythm dominated by the parietal region, paroxysmal generalized spike-and-wave, or spike-and-wave in rolandic region or occipital region. Ictal: varies with the seizure type occurring [9-10].

Brain MRI: Most of them are normal.

Developmental progress: Basically normal.

 

References

  1. Spampanato, J., et al., Functional effects of two voltage-gated sodium channel mutations that cause generalized epilepsy with febrile seizures plus type 2.J Neurosci, 2001. 21(19): p. 7481-90.
  2. Wallace, R.H., et al., Febrile seizures and generalized epilepsy associated with a mutation in the Na+-channel beta1 subunit gene SCN1B.Nat Genet, 1998. 19(4): p. 366-70.
  3. Harkin, L.A., et al., Truncation of the GABA(A)-receptor gamma2 subunit in a family with generalized epilepsy with febrile seizures plus.Am J Hum Genet, 2002. 70(2): p. 530-6.
  4. Moller, R.S., et al., Mutations in GABRB3: From febrile seizures to epileptic encephalopathies. Neurology, 2017. 88(5): p. 483-492.
  5. Liu, X.W., et al., The finding of a new heterozygous mutation site of the SCN2A gene in a monozygotic twin family carrying and exhibiting genetic epilepsy with febrile seizures plus (GEFS+) using targeted next-generation sequencing. Clin Neurol Neurosurg, 2018. 169: p. 86-91.
  6. Depienne, C., et al., Mutations and deletions in PCDH19 account for various familial or isolated epilepsies in females. Hum Mutat, 2011. 32(1): p. E1959-75.
  7. Dibbens, L.M., et al., GABRD encoding a protein for extra- or peri-synaptic GABAA receptors is a susceptibility locus for generalized epilepsies.Hum Mol Genet, 2004. 13(13): p. 1315-9.
  8. Yang, Y., et al., Phenotypic spectrum of patients with GABRB2 variants: from mild febrile seizures to severe epileptic encephalopathy. Dev Med Child Neurol, 2020. 62(10): p. 1213-1220.
  9. Panayiotopoulos.  癫痫综合征及临床治疗.  北京 : 人民卫生出版社, 2012.
  10. 刘晓燕.  临床脑电图学. 第2版.  北京 : 人民卫生出版社, 2017.