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

Lookup NU author(s): Professor Rita Horvath

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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.


Publication metadata

Author(s): Weckhuysen S, Ivanovic V, Hendrickx R, Van Coster R, Hjalgrim H, Moller RS, Gronborg S, Schoonjans AS, Ceulemans B, Heavin SB, Eltze C, Horvath R, Casara G, Pisano T, Giordano L, Rostasy K, Haberlandt E, Albrecht B, Bevot A, Benkel I, Syrbe S, Sheidley B, Guerrini R, Poduri A, Lemke JR, Mandelstam S, Scheffer I, Angriman M, Striano P, Marini C, Suls A, De Jonghe P, KCNQ2 Study Group

Publication type: Article

Publication status: Published

Journal: Neurology

Year: 2013

Volume: 81

Issue: 19

Pages: 1697-1703

Print publication date: 09/10/2013

ISSN (print): 0028-3878

ISSN (electronic): 1526-632X

Publisher: Lippincott Williams & Wilkins

URL: http://dx.doi.org/10.1212/01.wnl.0000435296.72400.a1

DOI: 10.1212/01.wnl.0000435296.72400.a1


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