Journal Article

FZJ-2021-02067

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png The molecular and phenotypic spectrum of CLCN4-related epilepsy

He, H. ; Guzman, R.FZJ* ; Cao, D. ; Sierra-Marquez, J.FZJ* ; Yin, F. ; Fahlke, C.FZJ* ; Peng, J. (Corresponding author) ; Stauber, T.

2021
Wiley-Blackwell Oxford [u.a.]

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Please use a persistent id in citations: http://hdl.handle.net/2128/27935  doi:10.1111/epi.16906

Abstract: ObjectiveThis study was undertaken to expand the phenotypic and genetic spectrum of CLCN4-related epilepsy and to investigate genotype–phenotype correlations.MethodsWe systematically reviewed the phenotypic and genetic spectrum of newly diagnosed and previously reported patients with CLCN4-related epilepsy. Three novel variants identified in four patients reported in this study were evaluated through in silico prediction and functional analysis by Western blot, immunofluorescence, and electrophysiological measurements.ResultsEpilepsy was diagnosed in 54.55% (24/44) of individuals with CLCN4-related disorders and was drug-resistant in most cases. Of 24 patients, 15 had epileptic encephalopathy and four died at an early age; 69.57% of patients had seizure onset within the first year of life. Myoclonic seizures are the most common seizure type, and 56.25% of patients presented multiple seizure types. Notably, seizure outcome was favorable in individuals with only one seizure type. All patients showed intellectual disability, which was severe in 65.22% of patients. Additional common features included language delay, behavioral disorders, and dysmorphic features. Five patients benefitted from treatment with lamotrigine. Most variants, which were mainly missense (79.17%), were inherited (70.83%). Whereas frameshift, intragenic deletion, or inherited variants were associated with milder phenotypes, missense or de novo variants led to more severe phenotypes. All evaluated CLCN4 variants resulted in loss of function with reduced ClC-4 currents. Nonetheless, genotype–phenotype relationships for CLCN4-related epilepsy are not straightforward, as phenotypic variability was observed in recurrent variants and within single families.SignificancePathogenic CLCN4 variants contribute significantly to the genetic etiology of epilepsy. The phenotypic spectrum of CLCN4-related epilepsy includes drug-resistant seizures, cognitive and language impairment, behavioral disorders, and congenital anomalies. Notably, the mutation type and the number of seizure types correlate with the severity of the phenotype, suggesting its use for clinical prognosis. Lamotrigine can be considered a therapeutic option.

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Contributing Institute(s):

1. Molekular- und Zellphysiologie (IBI-1)

Research Program(s):

1. 524 - Molecular and Cellular Information Processing (POF4-524) (POF4-524)

Appears in the scientific report 2021

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