Browsing by Author "McWalter, Kirsty"

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    Biallelic CRELD1 variants cause a multisystem syndrome, including neurodevelopmental phenotypes, cardiac dysrhythmias, and frequent infections
    (Elsevier, 2024) Jeffries, Lauren; Mis, Emily K.; McWalter, Kirsty; Donkervoort, Sandra; Brodsky, Nina N.; Carpier, Jean-Marie; Ji, Weizhen; Ionita, Cristian; Roy, Bhaskar; Morrow, Jon S.; Darbinyan, Armine; Iyer, Krishna; Aul, Ritu B.; Banka, Siddharth; Chao, Katherine R.; Cobbold, Laura; Cohen, Stacey; Custodio, Helena M.; Drummond-Borg, Margaret; Elmslie, Frances; Finanger, Erika; Hainline, Bryan E.; Helbig, Ingo; Hewson, Stacy; Hu, Ying; Jackson, Adam; Josifova, Dragana; Konstantino, Monica; Leach, Meganne E.; Mak, Bryan; McCormick, David; McGee, Elisabeth; Nelson, Stanley; Nguyen, Joanne; Nugent, Kimberly; Ortega, Lucy; Goodkin, Howard P.; Roeder, Elizabeth; Roy, Sani; Sapp, Katie; Saade, Dimah; Sisodiya, Sanjay M.; Stals, Karen; Towner, Shelley; Wilson, William; Deciphering Developmental Disorders; Genomics England Research Consortium; Undiagnosed Disease Network; Khokha, Mustafa K.; Bönnemann, Carsten G.; Lucas, Carrie L.; Lakhani, Saquib A.; Medical and Molecular Genetics, School of Medicine
    Purpose: We sought to delineate a multisystem disorder caused by recessive cysteine-rich with epidermal growth factor-like domains 1 (CRELD1) gene variants. Methods: The impact of CRELD1 variants was characterized through an international collaboration utilizing next-generation DNA sequencing, gene knockdown, and protein overexpression in Xenopus tropicalis, and in vitro analysis of patient immune cells. Results: Biallelic variants in CRELD1 were found in 18 participants from 14 families. Affected individuals displayed an array of phenotypes involving developmental delay, early-onset epilepsy, and hypotonia, with about half demonstrating cardiac arrhythmias and some experiencing recurrent infections. Most harbored a frameshift in trans with a missense allele, with 1 recurrent variant, p.(Cys192Tyr), identified in 10 families. X tropicalis tadpoles with creld1 knockdown displayed developmental defects along with increased susceptibility to induced seizures compared with controls. Additionally, human CRELD1 harboring missense variants from affected individuals had reduced protein function, indicated by a diminished ability to induce craniofacial defects when overexpressed in X tropicalis. Finally, baseline analyses of peripheral blood mononuclear cells showed similar proportions of immune cell subtypes in patients compared with healthy donors. Conclusion: This patient cohort, combined with experimental data, provide evidence of a multisystem clinical syndrome mediated by recessive variants in CRELD1.
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    Boricua Founder Variant in FRRS1L Causes Epileptic Encephalopathy With Hyperkinetic Movements
    (Sage, 2021) Abdelmoumen, Imane; Jimenez, Sandra; Valencia, Ignacio; Melvin, Joseph; Legido, Agustin; Diaz-Diaz, Mayela M.; Griffith, Christopher; Massingham, Lauren J.; Yelton, Melissa; Rodríguez-Hernández, Janice; Schnur, Rhonda E.; Walsh, Laurence E.; Cristancho, Ana G.; Bergqvist, Christina A.; McWalter, Kirsty; Mathieson, Iain; Belbin, Gillian M.; Kenny, Eimear E.; Ortiz-Gonzalez, Xilma R.; Schneider, Michael C.; Neurology, School of Medicine
    Objective: To describe a founder mutation effect and the clinical phenotype of homozygous FRRS1L c.737_739delGAG (p.Gly246del) variant in 15 children of Puerto Rican (Boricua) ancestry presenting with early infantile epileptic encephalopathy (EIEE-37) with prominent movement disorder. Background: EIEE-37 is caused by biallelic loss of function variants in the FRRS1L gene, which is critical for AMPA-receptor function, resulting in intractable epilepsy and dyskinesia. Methods: A retrospective, multicenter chart review of patients sharing the same homozygous FRRS1L (p.Gly246del) pathogenic variant identified by clinical genetic testing. Clinical information was collected regarding neurodevelopmental outcomes, neuroimaging, electrographic features and clinical response to antiseizure medications. Results: Fifteen patients from 12 different families of Puerto Rican ancestry were homozygous for the FRRS1L (p.Gly246del) pathogenic variant, with ages ranging from 1 to 25 years. The onset of seizures was from 6 to 24 months. All had hypotonia, severe global developmental delay, and most had hyperkinetic involuntary movements. Developmental regression during the first year of life was common (86%). Electroencephalogram showed hypsarrhythmia in 66% (10/15), with many older children evolving into Lennox-Gastaut syndrome. Six patients demonstrated progressive volume loss and/or cerebellar atrophy on brain magnetic resonance imaging (MRI). Conclusions: We describe the largest cohort to date of patients with epileptic encephalopathy. We estimate that 0.76% of unaffected individuals of Puerto Rican ancestry carry this pathogenic variant due to a founder effect. Children homozygous for the FRRS1L (p.Gly246del) Boricua variant exhibit a very homogenous phenotype of early developmental regression and epilepsy, starting with infantile spasms and evolving into Lennox-Gastaut syndrome with hyperkinetic movement disorder.
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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.