Browsing by Author "Alkuraya, Fowzan S."

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    Complementation of hypersensitivity to DNA interstrand crosslinking agents demonstrates that XRCC2 is a Fanconi anaemia gene
    (BMJ Journals, 2016-10) Park, Jung-Young; Virts, Elizabeth L.; Jankowska, Anna; Wiek, Constanze; Othman, Mohamed; Chakraborty, Sujata C.; Vance, Gail H.; Alkuraya, Fowzan S.; Hanenberg, Helmut; Andreassen, Paul R.; Medical and Molecular Genetics, School of Medicine
    Background Fanconi anemia (FA) is a heterogeneous inherited disorder clinically characterized by progressive bone marrow failure, congenital anomalies, and a predisposition to malignancies. Objective Determine, based on correction of cellular phenotypes, whether XRCC2 is a FA gene. Methods Cells (900677) from a previously identified patient with biallelic mutation of XRCC2, among other mutations, were genetically complemented with wild-type XRCC2. Results Wild-type XRCC2 corrects each of three phenotypes characteristic of FA cells, all related to the repair of DNA interstrand crosslinks, including increased sensitivity to mitomycin C (MMC), chromosome breakage, and G2-M accumulation in the cell cycle. Further, the p.R215X mutant of XRCC2, which is harbored by the patient, is unstable. This provides an explanation for the pathogenesis of this mutant, as does the fact that 900677 cells have reduced levels of other proteins in the XRCC2-RAD51B-C-D complex. Also, FANCD2 monoubiquitination and foci formation, but not assembly of RAD51 foci, are normal in 900677 cells. Thus, XRCC2 acts late in the FA-BRCA pathway as also suggested by hypersensitivity of 900677 cells to ionizing radiation. These cells also share milder sensitivities toward olaparib and formaldehyde with certain other FA cells. Conclusions XRCC2/FANCU is a FA gene, as is another RAD51 paralog gene, RAD51C/FANCO. Notably, similar to a subset of FA genes that act downstream of FANCD2, biallelic mutation of XRCC2/FANCU has not been associated with bone marrow failure. Taken together, our results yield important insights into phenotypes related to FA and its genetic origins.
  • Thumbnail Image
    Item
    A dyadic approach to the delineation of diagnostic entities in clinical genomics
    (Cell Press, 2021-01-07) Biesecker, Leslie G.; Adam, Margaret P.; Alkuraya, Fowzan S.; Amemiya, Anne R.; Bamshad, Michael J.; Beck, Anita E.; Bennett, James T.; Bird, Lynne M.; Carey, John C.; Chung, Brian; Clark, Robin D.; Cox, Timothy C.; Curry, Cynthia; Palko Dinulos, Mary Beth; Dobyns, William B.; Giampietro, Philip F.; Girisha, Katta M.; Glass, Ian A.; Graham, John M., Jr.; Gripp, Karen W.; Haldeman-Englert, Chad R.; Hall, Bryan D.; Innes, A. Micheil; Kalish, Jennifer M.; Keppler-Noreuil, Kim M.; Kosaki, Kenjiro; Kozel, Beth A.; Mirzaa, Ghayda M.; Mulvihill, John J.; Nowaczyk, Malgorzata J.M.; Pagon, Roberta A.; Retterer, Kyle; Rope, Alan F.; Sanchez-Lara, Pedro A.; Seaver, Laurie H.; Shieh, Joseph T.; Slavotinek, Anne M.; Sobering, Andrew K.; Stevens, Cathy A.; Stevenson, David A.; Tan, Tiong Yang; Tan, Wen-Hann; Tsai, Anne C.; Weaver, David D.; Williams, Marc S.; Zackai, Elaine; Zarate, Yuri A.; Medical and Molecular Genetics, School of Medicine
    The delineation of disease entities is complex, yet recent advances in the molecular characterization of diseases provide opportunities to designate diseases in a biologically valid manner. Here, we have formalized an approach to the delineation of Mendelian genetic disorders that encompasses two distinct but inter-related concepts: (1) the gene that is mutated and (2) the phenotypic descriptor, preferably a recognizably distinct phenotype. We assert that only by a combinatorial or dyadic approach taking both of these attributes into account can a unitary, distinct genetic disorder be designated. We propose that all Mendelian disorders should be designated as "GENE-related phenotype descriptor" (e.g., "CFTR-related cystic fibrosis"). This approach to delineating and naming disorders reconciles the complexity of gene-to-phenotype relationships in a simple and clear manner yet communicates the complexity and nuance of these relationships.
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Phenotypic and biochemical analysis of an international cohort of individuals with variants in NAA10 and NAA15
    (Oxford University Press, 2019-05-01) Cheng, Hanyin; Gottlieb, Leah; Marchi, Elaine; Kleyner, Robert; Bhardwaj, Puja; Rope, Alan F.; Rosenheck, Sarah; Moutton, Sébastien; Philippe, Christophe; Eyaid, Wafaa; Alkuraya, Fowzan S.; Toribio, Janet; Mena, Rafael; Prada, Carlos E.; Stessman, Holly; Bernier, Raphael; Wermuth, Marieke; Kauffmann, Birgit; Blaumeiser, Bettina; Kooy, R Frank; Baralle, Diana; Mancini, Grazia M. S.; Conway, Simon J.; Xia, Fan; Chen, Zhao; Meng, Linyan; Mihajlovic, Ljubisa; Marmorstein, Ronen; Lyon, Gholson J.; Pediatrics, School of Medicine
    N-alpha-acetylation is one of the most common co-translational protein modifications in humans and is essential for normal cell function. NAA10 encodes for the enzyme NAA10, which is the catalytic subunit in the N-terminal acetyltransferase A (NatA) complex. The auxiliary and regulatory subunits of the NatA complex are NAA15 and Huntington-interacting protein (HYPK), respectively. Through a genotype-first approach with exome sequencing, we identified and phenotypically characterized 30 individuals from 30 unrelated families with 17 different de novo or inherited, dominantly acting missense variants in NAA10 or NAA15. Clinical features of affected individuals include variable levels of intellectual disability, delayed speech and motor milestones and autism spectrum disorder. Additionally, some subjects present with mild craniofacial dysmorphology, congenital cardiac anomalies and seizures. One of the individuals is an 11-year-old boy with a frameshift variant in exon 7 of NAA10, who presents most notably with microphthalmia, which confirms a prior finding with a single family with Lenz microphthalmia syndrome. Biochemical analyses of variants as part of the human NatA complex, as well as enzymatic analyses with and without the HYPK regulatory subunit, help to explain some of the phenotypic differences seen among the different variants.
  • Thumbnail Image
    Item
    Phenotypic and biochemical analysis of an international cohort of individuals with variants in NAA10 and NAA15
    (Oxford University Press, 2020-03-27) Cheng, Hanyin; Gottlieb, Leah; Marchi, Elaine; Kleyner, Robert; Bhardwaj, Puja; Rope, Alan F.; Rosenheck, Sarah; Moutton, Sébastien; Philippe, Christophe; Eyaid, Wafaa; Alkuraya, Fowzan S.; Toribio, Janet; Mena, Rafael; Prada, Carlos E.; Stessman, Holly; Bernier, Raphael; Wermuth, Marieke; Kauffmann, Birgit; Blaumeiser, Bettina; Kooy, R. Frank; Baralle, Diana; Mancini, Grazia M. S.; Conway, Simon J.; Xia, Fan; Chen, Zhao; Meng, Linyan; Mihajlovic, Ljubisa; Marmorstein, Ronen; Lyon, Gholson J.; Medicine, School of Medicine
    In the original version of this article, Ezzat El-Akkad’s name was misspelled in the acknowledgements section; this has now been corrected. The authors apologize for this error.
  • Thumbnail Image
    Item
    Response to Hamosh et al
    (Elsevier, 2021) Biesecker, Leslie G.; Adam, Margaret P.; Alkuraya, Fowzan S.; Amemiya, Anne R.; Bamshad, Michael J.; Beck, Anita E.; Bennett, James T.; Bird, Lynne M.; Carey, John C.; Chung, Brian; Clark, Robin D.; Cox, Timothy C.; Curry, Cynthia; Dinulos, Mary Beth Palko; Dobyns, William B.; Giampietro, Philip F.; Girisha, Katta M.; Glass, Ian A.; Graham, John M., Jr.; Gripp, Karen W.; Haldeman-Englert, Chad R.; Hall, Bryan D.; Innes, A. Micheil; Kalish, Jennifer M.; Keppler-Noreuil, Kim M.; Kosaki, Kenjiro; Kozel, Beth A.; Mirzaa, Ghayda M.; Mulvihill, John J.; Nowaczyk, Malgorzata J.M.; Pagon, Roberta A.; Retterer, Kyle; Rope, Alan F.; Sanchez-Lara, Pedro A.; Seaver, Laurie H.; Shieh, Joseph T.; Slavotinek, Anne M.; Sobering, Andrew K.; Stevens, Cathy A.; Stevenson, David A.; Tan, Tiong Yang; Tan, Wen-Hann; Tsai, Anne C.; Weaver, David D.; Williams, Marc S.; Zackai, Elaine; Zarate, Yuri A.; Medical and Molecular Genetics, School of Medicine