Browsing by Author "van der Spek, Peter J."

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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.
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    De Novo and Inherited Loss-of-Function Variants in TLK2: Clinical and Genotype-Phenotype Evaluation of a Distinct Neurodevelopmental Disorder
    (Elsevier, 2018-06-07) Reijnders, Margot R.F.; Miller, Kerry A.; Alvi, Mohsan; Goos, Jacqueline A.C.; Lees, Melissa M.; de Burca, Anna; Henderson, Alex; Kraus, Alison; Mikat, Barbara; de Vries, Bert B.A.; Isidor, Bertrand; Kerr, Bronwyn; Marcelis, Carlo; Schluth-Bolard, Caroline; Deshpande, Charu; Ruivenkamp, Claudia A.L.; Wieczorek, Dagmar; Baralle, Diana; Blair, Edward M.; Engels, Hartmut; Lüdecke, Hermann-Josef; Eason, Jacqueline; Santen, Gijs W.E.; Clayton-Smith, Jill; Chandler, Kate; Tatton-Brown, Katrina; Payne, Katelyn; Helbig, Katherine; Radtke, Kelly; Nugent, Kimberly M.; Cremer, Kirsten; Strom, Tim M.; Bird, Lynne M.; Sinnema, Margje; Bitner-Glindzicz, Maria; van Dooren, Marieke F.; Alders, Marielle; Koopmans, Marije; Brick, Lauren; Kozenko, Mariya; Harline, Megan L.; Klaassens, Merel; Steinraths, Michelle; Cooper, Nicola S.; Edery, Patrick; Yap, Patrick; Terhal, Paulien A.; van der Spek, Peter J.; Lakeman, Phillis; Taylor, Rachel L.; Littlejohn, Rebecca O.; Pfundt, Rolph; Mercimek-Andrews, Saadet; Stegmann, Alexander P.A.; Kant, Sarina G.; McLean, Scott; Joss, Shelagh; Swagemakers, Sigrid M.A.; Douzgou, Sofia; Wall, Steven A.; Küry, Sebastian; Calpena, Eduardo; Koelling, Nils; McGowan, Simon J.; Twigg, Stephen R.F.; Mathijssen, Irene M.J.; Nellaker, Christoffer; Brunner, Han G.; Wilkie, Andrew O.M.; Medical and Molecular Genetics, School of Medicine
    Next-generation sequencing is a powerful tool for the discovery of genes related to neurodevelopmental disorders (NDDs). Here, we report the identification of a distinct syndrome due to de novo or inherited heterozygous mutations in Tousled-like kinase 2 (TLK2) in 38 unrelated individuals and two affected mothers, using whole-exome and whole-genome sequencing technologies, matchmaker databases, and international collaborations. Affected individuals had a consistent phenotype, characterized by mild-borderline neurodevelopmental delay (86%), behavioral disorders (68%), severe gastro-intestinal problems (63%), and facial dysmorphism including blepharophimosis (82%), telecanthus (74%), prominent nasal bridge (68%), broad nasal tip (66%), thin vermilion of the upper lip (62%), and upslanting palpebral fissures (55%). Analysis of cell lines from three affected individuals showed that mutations act through a loss-of-function mechanism in at least two case subjects. Genotype-phenotype analysis and comparison of computationally modeled faces showed that phenotypes of these and other individuals with loss-of-function variants significantly overlapped with phenotypes of individuals with other variant types (missense and C-terminal truncating). This suggests that haploinsufficiency of TLK2 is the most likely underlying disease mechanism, leading to a consistent neurodevelopmental phenotype. This work illustrates the power of international data sharing, by the identification of 40 individuals from 26 different centers in 7 different countries, allowing the identification, clinical delineation, and genotype-phenotype evaluation of a distinct NDD caused by mutations in TLK2.