Biallelic ADAM22 pathogenic variants cause progressive encephalopathy and infantile-onset refractory epilepsy.

Pathogenic variants in A Disintegrin And Metalloproteinase (ADAM) 22, the postsynaptic cell membrane receptor for the glycoprotein leucine-rich repeat glioma-inactivated protein 1 (LGI1), have been recently associated with recessive developmental and epileptic encephalopathy. However, so far, only two affected individuals have been described and many features of this disorder are unknown. We refine the phenotype and report 19 additional individuals harbouring compound heterozygous or homozygous inactivating ADAM22 variants, of whom 18 had clinical data available. Additionally, we provide follow-up data from two previously reported cases. All affected individuals exhibited infantile-onset, treatment-resistant epilepsy. Additional clinical features included moderate to profound global developmental delay/intellectual disability (20/20), hypotonia (12/20) and delayed motor development (19/20). Brain MRI findings included cerebral atrophy (13/20), supported by post-mortem histological examination in patient-derived brain tissue, cerebellar vermis atrophy (5/20), and callosal hypoplasia (4/20). Functional studies in transfected cell lines confirmed the deleteriousness of all identified variants and indicated at least three distinct pathological mechanisms: (i) defective cell membrane expression; (ii) impaired LGI1-binding; and/or (iii) impaired interaction with the postsynaptic density protein PSD-95. We reveal novel clinical and molecular hallmarks of ADAM22 deficiency and provide knowledge that might inform clinical management and early diagnostics. © The Author(s) 2022. Published by Oxford University Press on behalf of the Guarantors of Brain.

Citation

Marieke M van der Knoop, Reza Maroofian, Yuko Fukata, Yvette van Ierland, Ehsan G Karimiani, Anna Elina Lehesjoki, Mikko Muona, Anders Paetau, Yuri Miyazaki, Yoko Hirano, Laila Selim, Marina de França, Rodrigo Ambrosio Fock, Christian Beetz, Claudia A L Ruivenkamp, Alison J Eaton, Francois D Morneau-Jacob, Lena Sagi-Dain, Lilach Shemer-Meiri, Amir Peleg, Jumana Haddad-Halloun, Daan J Kamphuis, Cacha M P C D Peeters-Scholte, Semra Hiz Kurul, Rita Horvath, Hanns Lochmüller, David Murphy, Stephan Waldmüller, Stephanie Spranger, David Overberg, Alison M Muir, Aboulfazl Rad, Barbara Vona, Firdous Abdulwahad, Sateesh Maddirevula, Inna S Povolotskaya, Victoria Y Voinova, Vykuntaraju K Gowda, Varunvenkat M Srinivasan, Fowzan S Alkuraya, Heather C Mefford, Majid Alfadhel, Tobias B Haack, Pasquale Striano, Mariasavina Severino, Masaki Fukata, Yvonne Hilhorst-Hofstee, Henry Houlden. Biallelic ADAM22 pathogenic variants cause progressive encephalopathy and infantile-onset refractory epilepsy. Brain : a journal of neurology. 2022 Jul 29;145(7):2301-2312

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PMID: 35373813

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