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NEXMIF encephalopathy: an X-linked disorder with male and female phenotypic patterns

2020; Elsevier BV; Volume: 23; Issue: 2 Linguagem: Inglês

10.1038/s41436-020-00988-9

1530-0366

Hannah Stamberger, Trine Bjørg Hammer, Elena Gardella, Danique R.M. Vlaskamp, Birgitte Bertelsen, Simone Mandelstam, Iris Lange, Jing Zhang, Candace T. Myers, Christina Fenger, Zaid Afawi, Edith P. Almanza Fuerte, Danielle M. Andrade, Yunus Balcik, Bruria Ben Zeev, Mark F. Bennett, Samuel F. Berkovic, Bertrand Isidor, Arjan Bouman, Eva H. Brilstra, Øyvind L. Busk, Anita Cairns, Roseline Caumes, Nicolas Chatron, Russell C. Dale, Christa de Geus, Patrick Edery, Deepak Gill, Jacob Bie Granild-Jensen, Lauren Gunderson, Boudewijn Gunning, Gali Heimer, Johan Robert Helle, Michael S. Hildebrand, Georgie Hollingsworth, Volodymyr Kharytonov, Eric W. Klee, Bobby P.C. Koeleman, David A. Koolen, Christian Korff, Sébastien Küry, Gaëtan Lesca, Dorit Lev, Richard J. Leventer, Mark T. Mackay, Erica L. Macke, Meriel McEntagart, Shekeeb S. Mohammad, Pauline Monin, Martino Montomoli, Éva Morava, Sébastien Moutton, Alison M. Muir, Elena Parrini, Peter Procopis, Emmanuelle Ranza, Laura Reed, Philipp S. Reif, Felix Rosenow, Massimiliano Rossi, Lynette G. Sadleir, Tara Sadoway, Helenius J. Schelhaas, Amy L. Schneider, Krati Shah, Ruth S. Shalev, Sanjay M. Sisodiya, Thomas Smol, Connie T. R. M. Stumpel, Kyra E. Stuurman, Joseph D. Symonds, Frédéric Tran Mau‐Them, Nienke E. Verbeek, Judith Verhoeven, Geoff Wallace, Keren Yosovich, Yuri A. Zárate, Ayelet Zerem, Sameer M. Zuberi, Renzo Guerrini, Heather C. Mefford, Chirag Patel, Yue-Hua Zhang, Rikke S. Møller, Ingrid E. Scheffer,

RNA modifications and cancer

PurposePathogenic variants in the X-linked gene NEXMIF (previously KIAA2022) are associated with intellectual disability (ID), autism spectrum disorder, and epilepsy. We aimed to delineate the female and male phenotypic spectrum of NEXMIF encephalopathy.MethodsThrough an international collaboration, we analyzed the phenotypes and genotypes of 87 patients with NEXMIF encephalopathy.ResultsSixty-three females and 24 males (46 new patients) with NEXMIF encephalopathy were studied, with 30 novel variants. Phenotypic features included developmental delay/ID in 86/87 (99%), seizures in 71/86 (83%) and multiple comorbidities. Generalized seizures predominated including myoclonic seizures and absence seizures (both 46/70, 66%), absence with eyelid myoclonia (17/70, 24%), and atonic seizures (30/70, 43%). Males had more severe developmental impairment; females had epilepsy more frequently, and varied from unaffected to severely affected. All NEXMIF pathogenic variants led to a premature stop codon or were deleterious structural variants. Most arose de novo, although X-linked segregation occurred for both sexes. Somatic mosaicism occurred in two males and a family with suspected parental mosaicism.ConclusionNEXMIF encephalopathy is an X-linked, generalized developmental and epileptic encephalopathy characterized by myoclonic–atonic epilepsy overlapping with eyelid myoclonia with absence. Some patients have developmental encephalopathy without epilepsy. Males have more severe developmental impairment. NEXMIF encephalopathy arises due to loss-of-function variants.