A homozygous MED11 C-terminal variant causes a lethal neurodegenerative disease
Elisa Calì, Sheng‐Jia Lin, Clarissa Rocca, Yavuz Şahin, Aisha Al Shamsi, Salima El Chehadeh, Myriam Châabouni, Kshitij Mankad, Evangelia Galanaki, Stéphanie Efthymiou, Sniya Sudhakar, Alkyoni Athanasiou‐Fragkouli, Tamer Çelik, Nejat Narlı, Sebastiano Bianca, David Murphy, Francisco Martins De Carvalho Moreira, Michael G. Hannah, Enrico Bugiardini, Yamna Kriouile, M. El Khorassani, M. Aguennouz, Stanislav Groppa, Blagovesta Marinova Karashova, Gabriella Di Rosa, Jatinder S. Goraya, Tipu Sultan, Daniela Avdjieva, Hadil Kathom, Radka Tincheva, Selina Banu, Pierangelo Veggiotti, Alberto Verrotti, Salvatore Savasta, Alfons Macaya Ruiz, Barbara Garavaglia, Eugenia Borgione, Savvas Papacostas, Chiara Compagnoni, Alessandra Piccirilli, Michail Vikelis, Viorica Chelban, Rauan Kaiyrzhanov, Andrea Cortese, Roisin Sullivan, Eleni Zamba Papanicolaou, Efthymios Dardiotis, Shazia Maqbool, Shahnaz Ibrahim, Salman Kirmani, Nuzhat Rana, Osama Atawneh, Shen‐Yang Lim, Mohd. Farooq Shaikh, Annarita Scardamaglia, George Koutsis, Salvatore Mangano, Carmela Scuderi, Eugenia Borgione, Giovanna Morello, Massimo Zollo, Gali Heimer, Pasquale Striano, Issam Al-Khawaja, Fuad Al-Mutairi, Fowzan S. Alkuraya, Mie Rizig, Chingiz Shashkin, Nazira Zharkynbekova, Kairgali Koneyev, Ganieva Manizha, Maksud Isrofilov, Ulviyya Guliyeva, Kamran Salayev, Samson Khachatryan, Georgia Xiromerisiou, Cleanthe Spanaki, Arianna Tucci, Chiara Fiorillo, Federico Rissotto, Francina Munell, Antonella Gagliano, Farida Jan, Roberto Chimenz, Eloisa Gitto, Caterina Cuppari, Carmelo Romeo, Francesca Magrinelli, Neerja Gupta, Madhulika Kabra, Hanène Benrhouma, Mériem Tazir, Luca Zagaroli, Claudia Caloisi, Cecilia Fabiano, Gabriella Bottone, Giovanni Farello, Sandra Di Fabio, Makram Obeid, Sophia Bakhtadze
Abstract
PURPOSE: The mediator (MED) multisubunit-complex modulates the activity of the transcriptional machinery, and genetic defects in different MED subunits (17, 20, 27) have been implicated in neurologic diseases. In this study, we identified a recurrent homozygous variant in MED11 (c.325C>T; p.Arg109Ter) in 7 affected individuals from 5 unrelated families. METHODS: To investigate the genetic cause of the disease, exome or genome sequencing were performed in 5 unrelated families identified via different research networks and Matchmaker Exchange. Deep clinical and brain imaging evaluations were performed by clinical pediatric neurologists and neuroradiologists. The functional effect of the candidate variant on both MED11 RNA and protein was assessed using reverse transcriptase polymerase chain reaction and western blotting using fibroblast cell lines derived from 1 affected individual and controls and through computational approaches. Knockouts in zebrafish were generated using clustered regularly interspaced short palindromic repeats/Cas9. RESULTS: The disease was characterized by microcephaly, profound neurodevelopmental impairment, exaggerated startle response, myoclonic seizures, progressive widespread neurodegeneration, and premature death. Functional studies on patient-derived fibroblasts did not show a loss of protein function but rather disruption of the C-terminal of MED11, likely impairing binding to other MED subunits. A zebrafish knockout model recapitulates key clinical phenotypes. CONCLUSION: Loss of the C-terminal of MED subunit 11 may affect its binding efficiency to other MED subunits, thus implicating the MED-complex stability in brain development and neurodegeneration.