KCNQ2 encephalopathy: Emerging phenotype of a neonatal epileptic encephalopathy

Bert M. Weckhuysen, Simone Mandelstam, Arvid Suls, D. Audenaert, T. De Coninck, Lieve Claes, L. Deprez, K. Smets, Dimitrina Hristova, Iglika Yordanova, A. Jordanova, B. Ceulemans, Anna Jansen, D. Hasaerts, Filip Roelens, L. Lagae, S. Yendle, Thorsten Stanley, Sarah Heron, John MulleySamuel Berkovic, Ingrid Scheffer, Peter De Jonghe, American Neurological Association

Onderzoeksoutput: Articlepeer review

388 Citaten (Scopus)


Objective: KCNQ2 and KCNQ3 mutations are known to be responsible for benign familial neonatal seizures (BFNS).
A few reports on patients with a KCNQ2 mutation with a more severe outcome exist, but a definite relationship has
not been established. In this study we investigated whether KCNQ2/3 mutations are a frequent cause of epileptic
encephalopathies with an early onset and whether a recognizable phenotype exists.
Methods: We analyzed 80 patients with unexplained neonatal or early-infantile seizures and associated psychomotor
retardation for KCNQ2 and KCNQ3 mutations. Clinical and imaging data were reviewed in detail.
Results: We found 7 different heterozygous KCNQ2 mutations in 8 patients (8/80; 10%); 6 mutations arose de novo.
One parent with a milder phenotype was mosaic for the mutation. No KCNQ3 mutations were found. The 8 patients
had onset of intractable seizures in the first week of life with a prominent tonic component. Seizures generally
resolved by age 3 years but the children had profound, or less frequently severe, intellectual disability with motor
impairment. Electroencephalography (EEG) at onset showed a burst-suppression pattern or multifocal epileptiform
activity. Early magnetic resonance imaging (MRI) of the brain showed characteristic hyperintensities in the basal
ganglia and thalamus that later resolved.
Interpretation: KCNQ2 mutations are found in a substantial proportion of patients with a neonatal epileptic
encephalopathy with a potentially recognizable electroclinical and radiological phenotype. This suggests that KCNQ2
screening should be included in the diagnostic workup of refractory neonatal seizures of unknown origin.
Originele taal-2English
Pagina's (van-tot)15-25
Aantal pagina's11
TijdschriftAnnals of Neurology
StatusPublished - jan 2012

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