Browsing by Author "Efthymiou, Stephanie"

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    Delineating the molecular and phenotypic spectrum of the SETD1B-related syndrome
    (Elsevier, 2021-11) Weerts, Marjolein J.A.; Lanko, Kristina; Guzmán-Vega, Francisco J.; Jackson, Adam; Ramakrishnan, Reshmi; Cardona-Londoño, Kelly J.; Peña-Guerra, Karla A.; van Bever, Yolande; van Paassen, Barbara W.; Kievit, Anneke; van Slegtenhorst, Marjon; Allen, Nicholas M.; Kehoe, Caroline M.; Robinson, Hannah K.; Pang, Lewis; Banu, Selina H.; Zaman, Mashaya; Efthymiou, Stephanie; Houlden, Henry; Järvelä, Irma; Lauronen, Leena; Määttä, Tuomo; Schrauwen, Isabelle; Leal, Suzanne M.; Ruivenkamp, Claudia A.L.; Barge-Schaapveld, Daniela Q.C.M.; Peeters-Scholte, Cacha M.P.C.D.; Galehdari, Hamid; Mazaheri, Neda; Sisodiya, Sanjay M.; Harrison, Victoria; Sun, Angela; Thies, Jenny; Pedroza, Luis Alberto; Lara-Taranchenko, Yana; Chinn, Ivan K.; Lupski, James R.; Garza-Flores, Alexandra; McGlothlin, Jeffery; Yang, Lin; Huang, Shaoping; Wang, Xiaodong; Jewett, Tamison; Rosso, Gretchen; Lin, Xi; Mohammed, Shehla; Merritt, J. Lawrence, II.; Mirzaa, Ghayda M.; Timms, Andrew E.; Scheck, Joshua; Elting, Mariet W.; Polstra, Abeltje M.; Schenck, Lauren; Ruzhnikov, Maura R.Z.; Vetro, Annalisa; Montomoli, Martino; Guerrini, Renzo; Koboldt, Daniel C.; Mihalic Mosher, Theresa; Pastore, Matthew T.; McBride, Kim L.; Peng, Jing; Pan, Zou; Willemsen, Marjolein; Koning, Susanne; Turnpenny, Peter D.; de Vries, Bert B.A.; Gilissen, Christian; Pfundt, Rolph; Lees, Melissa; Braddock, Stephen R.; Klemp, Kara C.; Vansenne, Fleur; van Gijn, Marielle E.; Quindipan, Catherine; Deardorff, Matthew A.; Hamm, J. Austin; Putnam, Abbey M.; Baud, Rebecca; Walsh, Laurence; Lynch, Sally A.; Baptista, Julia; Person, Richard E.; Monaghan, Kristin G.; Crunk, Amy; Keller-Ramey, Jennifer; Reich, Adi; Elloumi, Houda Zghal; Alders, Marielle; Kerkhof, Jennifer; McConkey, Haley; Haghshenas, Sadegheh; Maroofian, Reza; Sadikovic, Bekim; Banka, Siddharth; Arold, Stefan T.; Barakat, Tahsin Stefan; Medical and Molecular Genetics, School of Medicine
    Purpose: Pathogenic variants in SETD1B have been associated with a syndromic neurodevelopmental disorder including intellectual disability, language delay, and seizures. To date, clinical features have been described for 11 patients with (likely) pathogenic SETD1B sequence variants. This study aims to further delineate the spectrum of the SETD1B-related syndrome based on characterizing an expanded patient cohort. Methods: We perform an in-depth clinical characterization of a cohort of 36 unpublished individuals with SETD1B sequence variants, describing their molecular and phenotypic spectrum. Selected variants were functionally tested using in vitro and genome-wide methylation assays. Results: Our data present evidence for a loss-of-function mechanism of SETD1B variants, resulting in a core clinical phenotype of global developmental delay, language delay including regression, intellectual disability, autism and other behavioral issues, and variable epilepsy phenotypes. Developmental delay appeared to precede seizure onset, suggesting SETD1B dysfunction impacts physiological neurodevelopment even in the absence of epileptic activity. Males are significantly overrepresented and more severely affected, and we speculate that sex-linked traits could affect susceptibility to penetrance and the clinical spectrum of SETD1B variants. Conclusion: Insights from this extensive cohort will facilitate the counseling regarding the molecular and phenotypic landscape of newly diagnosed patients with the SETD1B-related syndrome.
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    MED27 Variants Cause Developmental Delay, Dystonia, and Cerebellar Hypoplasia
    (Wiley, 2021) Meng, Linyan; Isohanni, Pirjo; Shao, Yunru; Graham, Brett H.; Hickey, Scott E.; Brooks, Stephanie; Suomalainen, Anu; Joset, Pascal; Steindl, Katharina; Rauch, Anita; Hackenberg, Annette; High, Frances A.; Armstrong-Javors, Amy; Mencacci, Niccolò E.; Gonzàlez-Latapi, Paulina; Kamel, Walaa A.; Al-Hashel, Jasem Y.; Bustos, Bernabé I.; Hernandez, Alejandro V.; Krainc, Dimitri; Lubbe, Steven J.; Van Esch, Hilde; De Luca, Chiara; Ballon, Katleen; Ravelli, Claudia; Burglen, Lydie; Qebibo, Leila; Calame, Daniel G.; Mitani, Tadahiro; Marafi, Dana; Pehlivan, Davut; Saadi, Nebal W.; Sahin, Yavuz; Maroofian, Reza; Efthymiou, Stephanie; Houlden, Henry; Maqbool, Shazia; Rahman, Fatima; Gu, Shen; Posey, Jennifer E.; Lupski, James R.; Hunter, Jill V.; Wangler, Michael F.; Carroll, Christopher J.; Yang, Yaping; Medical and Molecular Genetics, School of Medicine
    The Mediator multiprotein complex functions as a regulator of RNA polymerase II-catalyzed gene transcription. In this study, exome sequencing detected biallelic putative disease-causing variants in MED27, encoding Mediator complex subunit 27, in 16 patients from 11 families with a novel neurodevelopmental syndrome. Patient phenotypes are highly homogeneous, including global developmental delay, intellectual disability, axial hypotonia with distal spasticity, dystonic movements, and cerebellar hypoplasia. Seizures and cataracts were noted in severely affected individuals. Identification of multiple patients with biallelic MED27 variants supports the critical role of MED27 in normal human neural development, particularly for the cerebellum.
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    The clinical and genetic spectrum of inherited glycosylphosphatidylinositol deficiency disorders
    (Oxford University Press, 2024) Sidpra, Jai; Sudhakar, Sniya; Biswas, Asthik; Massey, Flavia; Turchetti, Valentina; Lau, Tracy; Cook, Edward; Alvi, Javeria Raza; Elbendary, Hasnaa M.; Jewell, Jerry L.; Riva, Antonella; Orsini, Alessandro; Vignoli, Aglaia; Federico, Zara; Rosenblum, Jessica; Schoonjans, An-Sofie; de Wachter, Matthias; Alvarez, Ignacio Delgado; Felipe-Rucián, Ana; Haridy, Nourelhoda A.; Haider, Shahzad; Zaman, Mashaya; Banu, Selina; Anwaar, Najwa; Rahman, Fatima; Maqbool, Shazia; Yadav, Rashmi; Salpietro, Vincenzo; Maroofian, Reza; Patel, Rajan; Radhakrishnan, Rupa; Prabhu, Sanjay P.; Lichtenbelt, Klaske; Stewart, Helen; Murakami, Yoshiko; Löbel, Ulrike; D'Arco, Felice; Wakeling, Emma; Jones, Wendy; Hay, Eleanor; Bhate, Sanjay; Jacques, Thomas S.; Mirsky, David M.; Whitehead, Matthew T.; Zaki, Maha S.; Sultan, Tipu; Striano, Pasquale; Jansen, Anna C.; Lequin, Maarten; de Vries, Linda S.; Severino, Mariasavina; Edmondson, Andrew C.; Menzies, Lara; Campeau, Philippe M.; Houlden, Henry; McTague, Amy; Efthymiou, Stephanie; Mankad, Kshitij; Radiology and Imaging Sciences, School of Medicine
    Inherited glycosylphosphatidylinositol deficiency disorders (IGDs) are a group of rare multisystem disorders arising from pathogenic variants in glycosylphosphatidylinositol anchor pathway (GPI-AP) genes. Despite associating 24 of at least 31 GPI-AP genes with human neurogenetic disease, prior reports are limited to single genes without consideration of the GPI-AP as a whole and with limited natural history data. In this multinational retrospective observational study, we systematically analyse the molecular spectrum, phenotypic characteristics and natural history of 83 individuals from 75 unique families with IGDs, including 70 newly reported individuals; the largest single cohort to date. Core clinical features were developmental delay or intellectual disability (DD/ID, 90%), seizures (83%), hypotonia (72%) and motor symptoms (64%). Prognostic and biologically significant neuroimaging features included cerebral atrophy (75%), cerebellar atrophy (60%), callosal anomalies (57%) and symmetric restricted diffusion of the central tegmental tracts (60%). Sixty-one individuals had multisystem involvement including gastrointestinal (66%), cardiac (19%) and renal (14%) anomalies. Though dysmorphic features were appreciated in 82%, no single dysmorphic feature had a prevalence >30%, indicating substantial phenotypic heterogeneity. Follow-up data were available for all individuals, 15 of whom were deceased at the time of writing. Median age at seizure onset was 6 months. Individuals with variants in synthesis stage genes of the GPI-AP exhibited a significantly shorter time to seizure onset than individuals with variants in transamidase and remodelling stage genes of the GPI-AP (P = 0.046). Forty individuals had intractable epilepsy. The majority of individuals experienced delayed or absent speech (95%), motor delay with non-ambulance (64%), and severe-to-profound DD/ID (59%). Individuals with a developmental epileptic encephalopathy (51%) were at greater risk of intractable epilepsy (P = 0.003), non-ambulance (P = 0.035), ongoing enteral feeds (P < 0.001) and cortical visual impairment (P = 0.007). Serial neuroimaging showed progressive cerebral volume loss in 87.5% and progressive cerebellar atrophy in 70.8%, indicating a neurodegenerative process. Genetic analyses identified 93 unique variants (106 total), including 22 novel variants. Exploratory analyses of genotype-phenotype correlations using unsupervised hierarchical clustering identified novel genotypic predictors of clinical phenotype and long-term outcome with meaningful implications for management. In summary, we expand both the mild and severe phenotypic extremities of the IGDs, provide insights into their neurological basis, and vitally, enable meaningful genetic counselling for affected individuals and their families.