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IQSEC2-related encephalopathy in males and females: a comparative study including 37 novel patients

2018; Elsevier BV; Volume: 21; Issue: 4 Linguagem: Inglês

10.1038/s41436-018-0268-1

1530-0366

Cyril Mignot, Aoife McMahon, Claire Bar, Philippe M. Campeau, Claire Davidson, Julien Buratti, Caroline Nava, Marie‐Line Jacquemont, Marilyn Tallot, Mathieu Milh, Patrick Edery, Pauline Marzin, Giulia Barcia, Christine Barnérias, Claude Besmond, Thierry Bienvenu, Ange-Line Bruel, Ledia Brunga, Berten Ceulemans, Christine Coubes, Ana G. Cristancho, Fiona Cunningham, Marie-Bertille Dehouck, Elizabeth Donner, Bénédicte Duban‐Bedu, Christèle Dubourg, Elena Gardella, Julie Gauthier, David Geneviève, Stéphanie Gobin-Limballe, Ethan M. Goldberg, Eveline Hagebeuk, Fadi F. Hamdan, Miroslava Hančárová, Laurence Hubert, Christine Ioos, Shoji Ichikawa, Sandra Janssens, Hubert Journel, Anna Kamińska, Boris Keren, Marion Koopmans, Caroline Lacoste, Petra Laššuthová, Damien Lederer, Daphné Lehalle, Dragan Marjanović, Julia Métreau, Jacques L Michaud, Kathryn Miller, Berge A. Minassian, Joannella Morales, Marie‐Laure Moutard, Arnold Munnich, Xilma R. Ortiz‐González, Jean-Marc Pinard, Darina Prchalová, Audrey Putoux, Chloé Quēlin, Alyssa Rosen, J. Roume, Elsa Rossignol, Marleen Simon, Thomas Smol, Natasha Shur, Ivan Shelihan, Katalin Štěrbová, Emílie Vyhnálková, Catheline Vilain, Julie Soblet, Guillaume Smits, Samuel Yang, Jasper J. van der Smagt, Peter M. van Hasselt, Marjan van Kempen, Sarah Weckhuysen, Ingo Helbig, Laurent Villard, Delphine Héron, Bobby P.C. Koeleman, Rikke S. Møller, Gaëtan Lesca, Katherine L. Helbig, Rima Nabbout, Nienke E. Verbeek, Christel Depienne,

DNA Repair Mechanisms

PurposeVariants in IQSEC2, escaping X inactivation, cause X-linked intellectual disability with frequent epilepsy in males and females. We aimed to investigate sex-specific differences.MethodsWe collected the data of 37 unpublished patients (18 males and 19 females) with IQSEC2 pathogenic variants and 5 individuals with variants of unknown significance and reviewed published variants. We compared variant types and phenotypes in males and females and performed an analysis of IQSEC2 isoforms.ResultsIQSEC2 pathogenic variants mainly led to premature truncation and were scattered throughout the longest brain-specific isoform, encoding the synaptic IQSEC2/BRAG1 protein. Variants occurred de novo in females but were either de novo (2/3) or inherited (1/3) in males, with missense variants being predominantly inherited. Developmental delay and intellectual disability were overall more severe in males than in females. Likewise, seizures were more frequently observed and intractable, and started earlier in males than in females. No correlation was observed between the age at seizure onset and severity of intellectual disability or resistance to antiepileptic treatments.ConclusionThis study provides a comprehensive overview of IQSEC2-related encephalopathy in males and females, and suggests that an accurate dosage of IQSEC2 at the synapse is crucial during normal brain development.