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Extending the KCNQ2 encephalopathy spectrum: clinical and neuroimaging findings in 17 patients

(2013) NEUROLOGY. 81(19). p.1697-1703
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Abstract
Objectives: To determine the frequency of KCNQ2 mutations in patients with neonatal epileptic encephalopathy (NEE), and to expand the phenotypic spectrum of KCNQ2 epileptic encephalopathy. Methods: Eighty-four patients with unexplained NEE were screened for KCNQ2 mutations using classic Sanger sequencing. Clinical data of 6 additional patients with KCNQ2 mutations detected by gene panel were collected. Detailed phenotyping was performed with particular attention to seizure frequency, cognitive outcome, and video-EEG. Results: In the cohort, we identified 9 different heterozygous de novo KCNQ2 missense mutations in 11 of 84 patients (13%). Two of 6 missense mutations detected by gene panel were recurrent and present in patients of the cohort. Seizures at onset typically consisted of tonic posturing often associated with focal clonic jerking, and were accompanied by apnea with desaturation. One patient diagnosed by gene panel had seizure onset at the age of 5 months. Based on seizure frequency at onset and cognitive outcome, we delineated 3 clinical subgroups, expanding the spectrum of KCNQ2 encephalopathy to patients with moderate intellectual disability and/or infrequent seizures at onset. Recurrent mutations lead to relatively homogenous phenotypes. One patient responded favorably to retigabine; 5 patients had a good response to carbamazepine. In 6 patients, seizures with bradycardia were recorded. One patient died of probable sudden unexpected death in epilepsy. Conclusion: KCNQ2 mutations cause approximately 13% of unexplained NEE. Patients present with a wide spectrum of severity and, although rare, infantile epilepsy onset is possible.
Keywords
FAMILY, DISEASE, POTASSIUM CHANNEL GENE, EPILEPTIC ENCEPHALOPATHY, NEONATAL CONVULSIONS, SEIZURES, MUTATION

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Chicago
Weckhuysen, Sarah, Vanja Ivanovic, Rik Hendrickx, Rudy Van Coster, Helle Hjalgrim, Rikke S Møller, Sabine Grønborg, et al. 2013. “Extending the KCNQ2 Encephalopathy Spectrum: Clinical and Neuroimaging Findings in 17 Patients.” Neurology 81 (19): 1697–1703.
APA
Weckhuysen, S., Ivanovic, V., Hendrickx, R., Van Coster, R., Hjalgrim, H., Møller, R. S., Grønborg, S., et al. (2013). Extending the KCNQ2 encephalopathy spectrum: clinical and neuroimaging findings in 17 patients. NEUROLOGY, 81(19), 1697–1703.
Vancouver
1.
Weckhuysen S, Ivanovic V, Hendrickx R, Van Coster R, Hjalgrim H, Møller RS, et al. Extending the KCNQ2 encephalopathy spectrum: clinical and neuroimaging findings in 17 patients. NEUROLOGY. 2013;81(19):1697–703.
MLA
Weckhuysen, Sarah, Vanja Ivanovic, Rik Hendrickx, et al. “Extending the KCNQ2 Encephalopathy Spectrum: Clinical and Neuroimaging Findings in 17 Patients.” NEUROLOGY 81.19 (2013): 1697–1703. Print.
@article{5659719,
  abstract     = {Objectives: To determine the frequency of KCNQ2 mutations in patients with neonatal epileptic encephalopathy (NEE), and to expand the phenotypic spectrum of KCNQ2 epileptic encephalopathy.
Methods: Eighty-four patients with unexplained NEE were screened for KCNQ2 mutations using classic Sanger sequencing. Clinical data of 6 additional patients with KCNQ2 mutations detected by gene panel were collected. Detailed phenotyping was performed with particular attention to seizure frequency, cognitive outcome, and video-EEG.
Results: In the cohort, we identified 9 different heterozygous de novo KCNQ2 missense mutations in 11 of 84 patients (13\%). Two of 6 missense mutations detected by gene panel were recurrent and present in patients of the cohort. Seizures at onset typically consisted of tonic posturing often associated with focal clonic jerking, and were accompanied by apnea with desaturation. One patient diagnosed by gene panel had seizure onset at the age of 5 months. Based on seizure frequency at onset and cognitive outcome, we delineated 3 clinical subgroups, expanding the spectrum of KCNQ2 encephalopathy to patients with moderate intellectual disability and/or infrequent seizures at onset. Recurrent mutations lead to relatively homogenous phenotypes. One patient responded favorably to retigabine; 5 patients had a good response to carbamazepine. In 6 patients, seizures with bradycardia were recorded. One patient died of probable sudden unexpected death in epilepsy.
Conclusion: KCNQ2 mutations cause approximately 13\% of unexplained NEE. Patients present with a wide spectrum of severity and, although rare, infantile epilepsy onset is possible.},
  author       = {Weckhuysen, Sarah and Ivanovic, Vanja and Hendrickx, Rik and Van Coster, Rudy and Hjalgrim, Helle and M{\o}ller, Rikke S and Gr{\o}nborg, Sabine and Schoonjans, An-Sofie and Ceulemans, Berten and Heavin, Sinead B and Eltze, Christin and Horvath, Rita and Casara, Gianluca and Pisano, Tiziana and Giordano, Lucio and Rostasy, Kevin and Haberlandt, Edda and Albrecht, Beate and Bevot, Andrea and Benkel, Ira and Syrbe, Steffan and Sheidley, Beth and Guerrini, Renzo and Poduri, Annapurna and Lemke, Johannes R and Mandelstam, Simone and Scheffer, Ingrid and Angriman, Marco and Striano, Pasquale and Marini, Carla and Suls, Arvid and De Jonghe, Peter},
  issn         = {0028-3878},
  journal      = {NEUROLOGY},
  language     = {eng},
  number       = {19},
  pages        = {1697--1703},
  title        = {Extending the KCNQ2 encephalopathy spectrum: clinical and neuroimaging findings in 17 patients},
  url          = {http://dx.doi.org/10.1212/01.wnl.0000435296.72400.a1},
  volume       = {81},
  year         = {2013},
}

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