Browsing by Author "Au, P.Y. Billie"

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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.
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    WDR26 Haploinsufficiency Causes a Recognizable Syndrome of Intellectual Disability, Seizures, Abnormal Gait, and Distinctive Facial Features
    (Elsevier, 2017-07-06) Skraban, Cara M.; Wells, Constance F.; Markose, Preetha; Cho, Megan T.; Nesbitt, Addie I.; Au, P.Y. Billie; Begtrup, Amber; Bernat, John A.; Bird, Lynne M.; Cao, Kajia; de Brouwer, Arjan P.M.; Denenberg, Elizabeth H.; Douglas, Ganka; Gibson, Kristin M.; Grand, Katheryn; Goldenberg, Alice; Innes, A. Micheil; Juusola, Jane; Kempers, Marlies; Kinning, Esther; Markie, David M.; Owens, Martina M.; Payne, Katelyn; Person, Richard; Pfundt, Rolph; Stocco, Amber; Turner, Claire L.S.; Verbeek, Nienke E.; Walsh, Laurence E.; Warner, Taylor C.; Wheeler, Patricia G.; Wieczorek, Dagmar; Wilkens, Alisha B.; Zonneveld-Huijssoon, Evelien; Deciphering Developmental Disorders Study; Kleefstra, Tjitske; Robertson, Stephen P.; Santani, Avni; van Gassen, Koen L.I.; Deardorf, Matthew A.; Pediatrics, School of Medicine
    We report 15 individuals with de novo pathogenic variants in WDR26. Eleven of the individuals carry loss-of-function mutations, and four harbor missense substitutions. These 15 individuals comprise ten females and five males, and all have intellectual disability with delayed speech, a history of febrile and/or non-febrile seizures, and a wide-based, spastic, and/or stiff-legged gait. These subjects share a set of common facial features that include a prominent maxilla and upper lip that readily reveal the upper gingiva, widely spaced teeth, and a broad nasal tip. Together, these features comprise a recognizable facial phenotype. We compared these features with those of chromosome 1q41q42 microdeletion syndrome, which typically contains WDR26, and noted that clinical features are consistent between the two subsets, suggesting that haploinsufficiency of WDR26 contributes to the pathology of 1q41q42 microdeletion syndrome. Consistent with this, WDR26 loss-of-function single-nucleotide mutations identified in these subjects lead to nonsense-mediated decay with subsequent reduction of RNA expression and protein levels. We derived a structural model of WDR26 and note that missense variants identified in these individuals localize to highly conserved residues of this WD-40-repeat-containing protein. Given that WDR26 mutations have been identified in ∼1 in 2,000 of subjects in our clinical cohorts and that WDR26 might be poorly annotated in exome variant-interpretation pipelines, we would anticipate that this disorder could be more common than currently appreciated.