Browsing by Author "Ockeloen, Charlotte W."

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    Functional and clinical studies reveal pathophysiological complexity of CLCN4-related neurodevelopmental condition
    (Springer Nature, 2023) Palmer, Elizabeth E.; Pusch, Michael; Picollo, Alessandra; Forwood, Caitlin; Nguyen, Matthew H.; Suckow, Vanessa; Gibbons, Jessica; Hoff, Alva; Sigfrid, Lisa; Megarbane, Andre; Nizon, Mathilde; Cogné, Benjamin; Beneteau, Claire; Alkuraya, Fowzan S.; Chedrawi, Aziza; Hashem, Mais O.; Stamberger, Hannah; Weckhuysen, Sarah; Vanlander, Arnaud; Ceulemans, Berten; Rajagopalan, Sulekha; Nunn, Kenneth; Arpin, Stéphanie; Raynaud, Martine; Motter, Constance S.; Ward-Melver, Catherine; Janssens, Katrien; Meuwissen, Marije; Beysen, Diane; Dikow, Nicola; Grimmel, Mona; Haack, Tobias B.; Clement, Emma; McTague, Amy; Hunt, David; Townshend, Sharron; Ward, Michelle; Richards, Linda J.; Simons, Cas; Costain, Gregory; Dupuis, Lucie; Mendoza-Londono, Roberto; Dudding-Byth, Tracy; Boyle, Jackie; Saunders, Carol; Fleming, Emily; El Chehadeh, Salima; Spitz, Marie-Aude; Piton, Amelie; Gerard, Bénédicte; Warde, Marie-Thérèse Abi; Rea, Gillian; McKenna, Caoimhe; Douzgou, Sofia; Banka, Siddharth; Akman, Cigdem; Bain, Jennifer M.; Sands, Tristan T.; Wilson, Golder N.; Silvertooth, Erin J.; Miller, Lauren; Lederer, Damien; Sachdev, Rani; Macintosh, Rebecca; Monestier, Olivier; Karadurmus, Deniz; Collins, Felicity; Carter, Melissa; Rohena, Luis; Willemsen, Marjolein H.; Ockeloen, Charlotte W.; Pfundt, Rolph; Kroft, Sanne D.; Field, Michael; Laranjeira, Francisco E. R.; Fortuna, Ana M.; Soares, Ana R.; Michaud, Vincent; Naudion, Sophie; Golla, Sailaja; Weaver, David D.; Bird, Lynne M.; Friedman, Jennifer; Clowes, Virginia; Joss, Shelagh; Pölsler, Laura; Campeau, Philippe M.; Blazo, Maria; Bijlsma, Emilia K.; Rosenfeld, Jill A.; Beetz, Christian; Powis, Zöe; McWalter, Kirsty; Brandt, Tracy; Torti, Erin; Mathot, Mikaël; Mohammad, Shekeeb S.; Armstrong, Ruth; Kalscheuer, Vera M.; Medical and Molecular Genetics, School of Medicine
    Missense and truncating variants in the X-chromosome-linked CLCN4 gene, resulting in reduced or complete loss-of-function (LOF) of the encoded chloride/proton exchanger ClC-4, were recently demonstrated to cause a neurocognitive phenotype in both males and females. Through international clinical matchmaking and interrogation of public variant databases we assembled a database of 90 rare CLCN4 missense variants in 90 families: 41 unique and 18 recurrent variants in 49 families. For 43 families, including 22 males and 33 females, we collated detailed clinical and segregation data. To confirm causality of variants and to obtain insight into disease mechanisms, we investigated the effect on electrophysiological properties of 59 of the variants in Xenopus oocytes using extended voltage and pH ranges. Detailed analyses revealed new pathophysiological mechanisms: 25% (15/59) of variants demonstrated LOF, characterized by a "shift" of the voltage-dependent activation to more positive voltages, and nine variants resulted in a toxic gain-of-function, associated with a disrupted gate allowing inward transport at negative voltages. Functional results were not always in line with in silico pathogenicity scores, highlighting the complexity of pathogenicity assessment for accurate genetic counselling. The complex neurocognitive and psychiatric manifestations of this condition, and hitherto under-recognized impacts on growth, gastrointestinal function, and motor control are discussed. Including published cases, we summarize features in 122 individuals from 67 families with CLCN4-related neurodevelopmental condition and suggest future research directions with the aim of improving the integrated care for individuals with this diagnosis.
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    Missense variants in ANKRD11 cause KBG syndrome by impairment of stability or transcriptional activity of the encoded protein
    (Elsevier, 2022-10) de Boer, Elke; Ockeloen, Charlotte W.; Kampen, Rosalie A.; Hampstead, Juliet E.; Dingemans, Alexander J. M.; Rots, Dmitrijs; Lütje, Lukas; Ashraf, Tazeen; Baker, Rachel; Barat-Houari, Mouna; Angle, Brad; Chatron, Nicolas; Denommé-Pichon, Anne-Sophie; Devinsky, Orrin; Dubourg, Christèle; Elmslie, Frances; Elloumi, Houda Zghal; Faivre, Laurence; Fitzgerald-Butt, Sarah; Geneviève, David; Goos, Jacqueline A. C.; Helm, Benjamin M.; Kini, Usha; Lasa-Aranzasti, Amaia; Lesca, Gaetan; Lynch, Sally A.; Mathijssen, Irene M. J.; McGowan, Ruth; Monaghan, Kristin G.; Odent, Syvie; Pfundt, Rolph; Putoux, Audrey; van Reeuwijk, Jeroen; Santen, Gijs W. E.; Sasaki, Erina; Sorlin, Arthur; van der Spek, Peter J.; Stegmann, Alexander P. A.; Swagemakers, Sigrid M. A.; Valenzuela, Irene; Viora-Dupont, Eléonore; Vitobello, Antonio; Ware, Stephanie M.; Wéber, Mathys; Gilissen, Christian; Low, Karen J.; Fisher, Simon E.; Vissers, Lisenka E. L. M.; Wong, Maggie M. K.; Kleefstra, Tjitske; Pediatrics, School of Medicine
    Purpose Although haploinsufficiency of ANKRD11 is among the most common genetic causes of neurodevelopmental disorders, the role of rare ANKRD11 missense variation remains unclear. We characterized clinical, molecular, and functional spectra of ANKRD11 missense variants. Methods We collected clinical information of individuals with ANKRD11 missense variants and evaluated phenotypic fit to KBG syndrome. We assessed pathogenicity of variants through in silico analyses and cell-based experiments. Results We identified 20 unique, mostly de novo, ANKRD11 missense variants in 29 individuals, presenting with syndromic neurodevelopmental disorders similar to KBG syndrome caused by ANKRD11 protein truncating variants or 16q24.3 microdeletions. Missense variants significantly clustered in repression domain 2 at the ANKRD11 C-terminus. Of the 10 functionally studied missense variants, 6 reduced ANKRD11 stability. One variant caused decreased proteasome degradation and loss of ANKRD11 transcriptional activity. Conclusion Our study indicates that pathogenic heterozygous ANKRD11 missense variants cause the clinically recognizable KBG syndrome. Disrupted transrepression capacity and reduced protein stability each independently lead to ANKRD11 loss-of-function, consistent with haploinsufficiency. This highlights the diagnostic relevance of ANKRD11 missense variants, but also poses diagnostic challenges because the KBG-associated phenotype may be mild and inherited pathogenic ANKRD11 (missense) variants are increasingly observed, warranting stringent variant classification and careful phenotyping.