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Title
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KCNQ2 encephalopathy : emerging phenotype of a neonatal epileptic encephalopathy
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Author
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Abstract
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| 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. ANN NEUROL 2012; 71: 15-25 |
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Language
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English
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Source (journal)
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Annals of neurology. - Boston, Mass.
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Publication
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Boston, Mass.
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2012
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ISSN
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0364-5134
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DOI
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10.1002/ANA.22644
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Volume/pages
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71
:1
(2012)
, p. 15-25
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ISI
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000299412200006
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Pubmed ID
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22275249
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Full text (Publisher's DOI)
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Full text (publisher's version - intranet only)
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