John Libbey Eurotext

Epileptic Disorders

The Educational Journal of the

A novel mutation in KCNQ3-related benign familial neonatal epilepsy: electroclinical features and neurodevelopmental outcome Volume 21, issue 1, February 2019

Video

  • A novel mutation in KCNQ3-related benign familial neonatal epilepsy: electroclinical features and neurodevelopmental outcome

Figures

  • Figure 1
  • Figure 2
Authors
1 Department of Sciences for Health Promotion and Mother and Child Care “G. D’Alessandro,” University of Palermo, Palermo
2 Laboratory of Human Genetics, Galliera Hospital, Genoa
3 Unit of Pharmacology, Department of Neuroscience, Reproductive and Odontostomatological Sciences, School of Medicine, University of Naples Federico II, Naples, Italy
* Correspondence: Salvatore Mangano Department of Sciences for Health Promotion and Mother and Child Care “G.D’Alessandro”, University of Palermo, Palermo, Italy
  • Key words: benign familial neonatal epilepsy, KCNQ, voltage-gated potassium channels, genotype-phenotype correlations, electroclinical features
  • DOI : 10.1684/epd.2019.1030
  • Page(s) : 87-91
  • Published in: 2019

Benign familial neonatal epilepsy (BFNE) is caused, in about 5% of families, by mutations in the KCNQ3 gene encoding voltage-gated potassium channel subunits. Usually, newborns with BFNE show a normal neurological outcome, but recently, refractory seizures and/or developmental disability have been reported suggesting phenotype variability associated with KCNQ3-related BFNE. Here, we describe a proband from a BFNE family carrying a novel variant in the KCNQ3 gene. Regarding the paucity of data in the literature, we describe the presented case with a view to further establishing: (1) a genotype/phenotype correlation in order to define a BFNE phenotype associated with favourable outcome; (2) an electroclinical pattern associated with BFNE based on video-EEG recording; (3) appropriate first-line AEDs; and (4) the duration of AED treatment. The presented case from Day 3 exhibited a cluster of ictal events, identified as epileptic seizures on Day 10 based on continuous video-EEG polygraphy. The seizures were characterized by asymmetric tonic posturing, associated with a generalized decrease in EEG amplitude, and followed by bilateral asynchronous clonic movements associated with bicentral sharp-wave discharges. The seizures were refractory to intravenous pyridoxine, whereas levetiracetam resulted in rapid total seizure control which has remained to date. This study demonstrates that the novel heterozygous KCNQ3 (c.914A>T; p.Asp305Val) variant, affecting residues in the pore region, is associated with a specific electroclinical pattern and favourable neurodevelopmental outcome. [Published with video sequence on www.epilepticdisorders.com]