Browsing by Author "Gecz, Jozef"

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    Macrocephaly and developmental delay caused by missense variants in RAB5C
    (Oxford University Press, 2023) Koop, Klaas; Yuan, Weimin; Tessadori, Federico; Rodriguez-Polanco, Wilmer R.; Grubbs, Jeremy; Zhang, Bo; Osmond, Matt; Graham, Gail; Sawyer, Sarah; Conboy, Erin; Vetrini, Francesco; Treat, Kayla; Płoski, Rafal; Pienkowski, Victor Murcia; Kłosowska, Anna; Fieg, Elizabeth; Krier, Joel; Mallebranche, Coralie; Alban, Ziegler; Aldinger, Kimberly A.; Ritter, Deborah; Macnamara, Ellen; Sullivan, Bonnie; Herriges, John; Alaimo, Joseph T.; Helbig, Catherine; Ellis, Colin A.; van Eyk, Clare; Gecz, Jozef; Farrugia, Daniel; Osei-Owusu, Ikeoluwa; Adès, Lesley; van den Boogaard, Marie-Jose; Fuchs, Sabine; Bakker, Jeroen; Duran, Karen; Dawson, Zachary D.; Lindsey, Anika; Huang, Huiyan; Baldridge, Dustin; Silverman, Gary A.; Grant, Barth D.; Raizen, David; Undiagnosed Diseases Network; van Haaften, Gijs; Pak, Stephen C.; Rehmann, Holger; Schedl, Tim; van Hasselt, Peter; Medical and Molecular Genetics, School of Medicine
    Rab GTPases are important regulators of intracellular vesicular trafficking. RAB5C is a member of the Rab GTPase family that plays an important role in the endocytic pathway, membrane protein recycling and signaling. Here we report on 12 individuals with nine different heterozygous de novo variants in RAB5C. All but one patient with missense variants (n = 9) exhibited macrocephaly, combined with mild-to-moderate developmental delay. Patients with loss of function variants (n = 2) had an apparently more severe clinical phenotype with refractory epilepsy and intellectual disability but a normal head circumference. Four missense variants were investigated experimentally. In vitro biochemical studies revealed that all four variants were damaging, resulting in increased nucleotide exchange rate, attenuated responsivity to guanine exchange factors and heterogeneous effects on interactions with effector proteins. Studies in C. elegans confirmed that all four variants were damaging in vivo and showed defects in endocytic pathway function. The variant heterozygotes displayed phenotypes that were not observed in null heterozygotes, with two shown to be through a dominant negative mechanism. Expression of the human RAB5C variants in zebrafish embryos resulted in defective development, further underscoring the damaging effects of the RAB5C variants. Our combined bioinformatic, in vitro and in vivo experimental studies and clinical data support the association of RAB5C missense variants with a neurodevelopmental disorder characterized by macrocephaly and mild-to-moderate developmental delay through disruption of the endocytic pathway.
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    A new microdeletion syndrome involving TBC1D24, ATP6V0C, and PDPK1 causes epilepsy, microcephaly, and developmental delay
    (Nature, 2018) Mucha, Bettina E.; Banka, Siddhart; Ajeawung, Norbert Fonya; Molidperee, Sirinart; Chen, Gary G.; Koenig, Mary Kay; Adejumo, Rhamat B.; Till, Marianne; Harbord, Michael; Perrier, Renee; Lemyre, Emmanuelle; Boucher, Renee-Myriam; Skotko, Brian G.; Waxler, Jessica L.; Thomas, Mary Ann; Hodge, Jennelle C.; Gecz, Jozef; Nicholl, Jillian; McGregor, Lesley; Linden, Tobias; Sisodiya, Sanjay M.; Sanlaville, Damien; Cheung, Sau W.; Ernst, Carl; Campeau, Philippe M.; Medical and Molecular Genetics, School of Medicine
    Purpose Contiguous gene deletions are known to cause several neurodevelopmental syndromes, many of which are caused by recurrent events on chromosome 16. However, chromosomal microarray studies (CMA) still yield copy-number variants (CNVs) of unknown clinical significance. We sought to characterize eight individuals with overlapping 205-kb to 504-kb 16p13.3 microdeletions that are distinct from previously published deletion syndromes. Methods Clinical information on the patients and bioinformatic scores for the deleted genes were analyzed. Results All individuals in our cohort displayed developmental delay, intellectual disability, and various forms of seizures. Six individuals were microcephalic and two had strabismus. The deletion was absent in all 13 parents who were available for testing. The area of overlap encompasses seven genes including TBC1D24, ATP6V0C, and PDPK1 (also known as PDK1). Bi-allelic TBC1D24 pathogenic variants are known to cause nonsyndromic deafness, epileptic disorders, or DOORS syndrome (deafness, onychodystrophy, osteodystrophy, mental retardation, seizures). Sanger sequencing of the nondeleted TBC1D24 allele did not yield any additional pathogenic variants. Conclusions We propose that 16p13.3 microdeletions resulting in simultaneous haploinsufficiencies of TBC1D24, ATP6V0C, and PDPK1 cause a novel rare contiguous gene deletion syndrome of microcephaly, developmental delay, intellectual disability, and epilepsy.
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    Rare deleterious mutations of HNRNP genes result in shared neurodevelopmental disorders
    (BMC, 2021-04-19) Gillentine, Madelyn A.; Wang, Tianyun; Hoekzema, Kendra; Rosenfeld, Jill; Liu, Pengfei; Guo, Hui; Kim, Chang N.; De Vries, Bert B.A.; Vissers, Lisenka E.L.M.; Nordenskjold, Magnus; Kvarnung, Malin; Lindstrand, Anna; Nordgren, Ann; Gecz, Jozef; Iascone, Maria; Cereda, Anna; Scatigno, Agnese; Maitz, Silvia; Zanni, Ginevra; Bertini, Enrico; Zweier, Christiane; Schuhmann, Sarah; Wiesener, Antje; Pepper, Micah; Panjwani, Heena; Torti, Erin; Abid, Farida; Anselm, Irina; Srivastava, Siddharth; Atwal, Paldeep; Bacino, Carlos A.; Bhat, Gifty; Cobian, Katherine; Bird, Lynne M.; Friedman, Jennifer; Wright, Meredith S.; Callewaert, Bert; Petit, Florence; Mathieu, Sophie; Afenjar, Alexandra; Christensen, Celenie K.; White, Kerry M.; Elpeleg, Orly; Berger, Itai; Espineli, Edward J.; Fagerberg, Christina; Brasch-Andersen, Charlotte; Hansen, Lars Kjærsgaard; Feyma, Timothy; Hughes, Susan; Thiffault, Isabelle; Sullivan, Bonnie; Yan, Shuang; Keller, Kory; Keren, Boris; Mignot, Cyril; Kooy, Frank; Meuwissen, Marije; Basinger, Alice; Kukolich, Mary; Philips, Meredith; Ortega, Lucia; Drummond-Borg, Margaret; Lauridsen, Mathilde; Sorensen, Kristina; Lehman, Anna; Lopez-Range, Elena; Levy, Paul; Lessel, Davor; Lotze, Timothy; Madan-Khetarpal, Suneeta; Sebastian, Jessica; Vento, Jodie; Vats, Divya; Benman, L. Manace; Mckee, Shane; Mirzaa, Ghayda M.; Muss, Candace; Pappas, John; Peeters, Hilde; Romano, Corrado; Elia, Maurizio; Galesi, Ornella; Simon, Marleen E.H.; Van Gassen, Koen L.I.; Simpson, Kara; Stratton, Robert; Syed, Sabeen; Thevenon, Julien; Palafoll, Irene Valenzuela; Vitobello, Antonio; Bournez, Marie; Faivre, Laurence; Xia, Kun; Earl, Rachel K.; Nowakowski, Tomasz; Bernier, Raphael A.; Eichler, Evan E.; Pediatrics, School of Medicine
    Background: With the increasing number of genomic sequencing studies, hundreds of genes have been implicated in neurodevelopmental disorders (NDDs). The rate of gene discovery far outpaces our understanding of genotype-phenotype correlations, with clinical characterization remaining a bottleneck for understanding NDDs. Most disease-associated Mendelian genes are members of gene families, and we hypothesize that those with related molecular function share clinical presentations. Methods: We tested our hypothesis by considering gene families that have multiple members with an enrichment of de novo variants among NDDs, as determined by previous meta-analyses. One of these gene families is the heterogeneous nuclear ribonucleoproteins (hnRNPs), which has 33 members, five of which have been recently identified as NDD genes (HNRNPK, HNRNPU, HNRNPH1, HNRNPH2, and HNRNPR) and two of which have significant enrichment in our previous meta-analysis of probands with NDDs (HNRNPU and SYNCRIP). Utilizing protein homology, mutation analyses, gene expression analyses, and phenotypic characterization, we provide evidence for variation in 12 HNRNP genes as candidates for NDDs. Seven are potentially novel while the remaining genes in the family likely do not significantly contribute to NDD risk. Results: We report 119 new NDD cases (64 de novo variants) through sequencing and international collaborations and combined with published clinical case reports. We consider 235 cases with gene-disruptive single-nucleotide variants or indels and 15 cases with small copy number variants. Three hnRNP-encoding genes reach nominal or exome-wide significance for de novo variant enrichment, while nine are candidates for pathogenic mutations. Comparison of HNRNP gene expression shows a pattern consistent with a role in cerebral cortical development with enriched expression among radial glial progenitors. Clinical assessment of probands (n = 188-221) expands the phenotypes associated with HNRNP rare variants, and phenotypes associated with variation in the HNRNP genes distinguishes them as a subgroup of NDDs. Conclusions: Overall, our novel approach of exploiting gene families in NDDs identifies new HNRNP-related disorders, expands the phenotypes of known HNRNP-related disorders, strongly implicates disruption of the hnRNPs as a whole in NDDs, and supports that NDD subtypes likely have shared molecular pathogenesis. To date, this is the first study to identify novel genetic disorders based on the presence of disorders in related genes. We also perform the first phenotypic analyses focusing on related genes. Finally, we show that radial glial expression of these genes is likely critical during neurodevelopment. This is important for diagnostics, as well as developing strategies to best study these genes for the development of therapeutics.