Browsing by Author "Griffith, Christopher"

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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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    Germline variants in tumor suppressor FBXW7 lead to impaired ubiquitination and a neurodevelopmental syndrome
    (Elsevier, 2022) Stephenson, Sarah E.M.; Costain, Gregory; Blok, Laura E.R.; Silk, Michael A.; Nguyen, Thanh Binh; Dong, Xiaomin; Alhuzaimi, Dana E.; Dowling, James J.; Walker, Susan; Amburgey, Kimberly; Hayeems, Robin Z.; Rodan, Lance H.; Schwartz, Marc A.; Picker, Jonathan; Lynch, Sally A.; Gupta, Aditi; Rasmussen, Kristen J.; Schimmenti, Lisa A.; Klee, Eric W.; Niu, Zhiyv; Agre, Katherine E.; Chilton, Ilana; Chung, Wendy K.; Revah-Politi, Anya; Au, P.Y. Billie; Griffith, Christopher; Racobaldo, Melissa; Raas-Rothschild, Annick; Zeev, Bruria Ben; Barel, Ortal; Moutton, Sebastien; Morice-Picard, Fanny; Carmignac, Virginie; Cornaton, Jenny; Marle, Nathalie; Devinsky, Orrin; Stimach, Chandler; Burns Wechsler, Stephanie; Hainline, Bryan E.; Sapp, Katie; Willems, Marjolaine; Bruel, Ange-Line; Dias, Kerith-Rae; Evans, Carey-Anne; Roscioli, Tony; Sachdev, Rani; Temple, Suzanna E.L.; Zhu, Ying; Baker, Joshua J.; Scheffer, Ingrid E.; Gardiner, Fiona J.; Schneider, Amy L.; Muir, Alison M.; Mefford, Heather C.; Crunk, Amy; Heise, Elizabeth M.; Millan, Francisca; Monaghan, Kristin G.; Person, Richard; Rhodes, Lindsay; Richards, Sarah; Wentzensen, Ingrid M.; Cogné, Benjamin; Isidor, Bertrand; Nizon, Mathilde; Vincent, Marie; Besnard, Thomas; Piton, Amelie; Marcelis, Carlo; Kato, Kohji; Koyama, Norihisa; Ogi, Tomoo; Suk-Ying Goh, Elaine; Richmond, Christopher; Amor, David J.; Boyce, Jessica O.; Morgan, Angela T.; Hildebrand, Michael S.; Kaspi, Antony; Bahlo, Melanie; Friðriksdóttir, Rún; Katrínardóttir, Hildigunnur; Sulem, Patrick; Stefánsson, Kári; Björnsson, Hans Tómas; Mandelstam, Simone; Morleo, Manuela; Mariani, Milena; TUDP Study Group; Scala, Marcello; Accogli, Andrea; Torella, Annalaura; Capra, Valeria; Wallis, Mathew; Jansen, Sandra; Weisfisz, Quinten; de Haan, Hugoline; Sadedin, Simon; Broad Center for Mendelian Genomics; Lim, Sze Chern; White, Susan M.; Ascher, David B.; Schenck, Annette; Lockhart, Paul J.; Christodoulou, John; Tan, Tiong Yang; Medical and Molecular Genetics, School of Medicine
    Neurodevelopmental disorders are highly heterogenous conditions resulting from abnormalities of brain architecture and/or function. FBXW7 (F-box and WD-repeat-domain-containing 7), a recognized developmental regulator and tumor suppressor, has been shown to regulate cell-cycle progression and cell growth and survival by targeting substrates including CYCLIN E1/2 and NOTCH for degradation via the ubiquitin proteasome system. We used a genotype-first approach and global data-sharing platforms to identify 35 individuals harboring de novo and inherited FBXW7 germline monoallelic chromosomal deletions and nonsense, frameshift, splice-site, and missense variants associated with a neurodevelopmental syndrome. The FBXW7 neurodevelopmental syndrome is distinguished by global developmental delay, borderline to severe intellectual disability, hypotonia, and gastrointestinal issues. Brain imaging detailed variable underlying structural abnormalities affecting the cerebellum, corpus collosum, and white matter. A crystal-structure model of FBXW7 predicted that missense variants were clustered at the substrate-binding surface of the WD40 domain and that these might reduce FBXW7 substrate binding affinity. Expression of recombinant FBXW7 missense variants in cultured cells demonstrated impaired CYCLIN E1 and CYCLIN E2 turnover. Pan-neuronal knockdown of the Drosophila ortholog, archipelago, impaired learning and neuronal function. Collectively, the data presented herein provide compelling evidence of an F-Box protein-related, phenotypically variable neurodevelopmental disorder associated with monoallelic variants in FBXW7.