Browsing by Author "Stevenson, David A."

Now showing 1 - 6 of 6
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    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.
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    Dystrophic spinal deformities in a neurofibromatosis type 1 murine model
    (PLoS, 2015-03-18) Rhodes, Steven D.; Zhang, Wei; Yang, Dalong; Yang, Hao; Chen, Shi; Wu, Xiahoua; Yang, Xianlin; Mohammad, Khalid S.; Guise, Theresa A.; Bergner, Amanda L.; Stevenson, David A.; Yang, Feng-Chun; Department of Anatomy and Cell Biology, IU School of Medicine
    Despite the high prevalence and significant morbidity of spinal anomalies in neurofibromatosis type 1 (NF1), the pathogenesis of these defects remains largely unknown. Here, we present two murine models: Nf1flox/-;PeriCre and Nf1flox/-;Col.2.3Cre mice, which recapitulate spinal deformities seen in the human disease. Dynamic histomorphometry and microtomographic studies show recalcitrant bone remodeling and distorted bone microarchitecture within the vertebral spine of Nf1flox/-;PeriCre and Nf1flox/-;Col2.3Cre mice, with analogous histological features present in a human patient with dystrophic scoliosis. Intriguingly, 36-60% of Nf1flox/-;PeriCre and Nf1flox/-;Col2.3Cre mice exhibit segmental vertebral fusion anomalies with boney obliteration of the intervertebral disc (IVD). While analogous findings have not yet been reported in the NF1 patient population, we herein present two case reports of IVD defects and interarticular vertebral fusion in patients with NF1. Collectively, these data provide novel insights regarding the pathophysiology of dystrophic spinal anomalies in NF1, and provide impetus for future radiographic analyses of larger patient cohorts to determine whether IVD and vertebral fusion defects may have been previously overlooked or underreported in the NF1 patient population.
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    Hyperactive Ras/MAPK signaling is critical for tibial nonunion fracture in neurofibromin-deficient mice
    (Oxford University Press, 2013-12-01) Sharma, Richa; Wu, Xiaohua; Rhodes, Steven D.; Chen, Shi; He, Yongzheng; Yuan, Jin; Li, Jiliang; Yang, Xianlin; Li, Xiaohong; Jiang, Li; Kim, Edward T.; Stevenson, David A.; Viskochil, David; Xu, Mingjiang; Yang, Feng-Chun; Department of Pediatrics, IU School of Medicine
    Neurofibromatosis type 1 (NF1) is a common genetic disorder affecting 1 in 3500 individuals. Patients with NF1 are predisposed to debilitating skeletal manifestations, including osteopenia/osteoporosis and long bone pseudarthrosis (nonunion fracture). Hyperactivation of the Ras/mitogen-activated protein kinase (MAPK) pathway in NF1 is known to underlie aberrant proliferation and differentiation in cell lineages, including osteoclast progenitors and mesenchymal stem cells (MSCs) also known as osteoblast progenitors (pro-OBLs). Our current study demonstrates the hyper Ras/MAPK as a critical pathway underlying the pathogenesis of NF1-associated fracture repair deficits. Nf1-deficient pro-OBLs exhibit Ras/MAPK hyperactivation. Introduction of the NF1 GTPase activating-related domain (NF1 GAP-related domain) in vitro is sufficient to rescue hyper Ras activity and enhance osteoblast (OBL) differentiation in Nf1−/− pro-OBLs and NF1 human (h) MSCs cultured from NF1 patients with skeletal abnormalities, including pseudarthrosis or scoliosis. Pharmacologic inhibition of mitogen-activated protein kinase kinase (MEK) signaling with PD98059 partially rescues aberrant Erk activation while enhancing OBL differentiation and expression of OBL markers, osterix and osteocalcin, in Nf1-deficient murine pro-OBLs. Similarly, MEK inhibition enhances OBL differentiation of hMSCs. In addition, PD98059 rescues aberrant osteoclast maturation in Nf1 haploinsufficient bone marrow mononuclear cells (BMMNCs). Importantly, MEK inhibitor significantly improves fracture healing in an NF1 murine model, Col2.3Cre
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    The path forward: 2015 International Children's Tumor Foundation conference on neurofibromatosis type 1, type 2, and schwannomatosis
    (Wiley, 2017-06) Blakely, Jaishri O.; Bakker, Annette; Barker, Anne; Clapp, Wade; Ferner, Rosalie; Fisher, Michael J.; Giovannini, Marco; Gutmann, David H.; Karajannis, Matthias A.; Kissil, Joseph L.; Legius, Eric; Lloyd, Alison C.; Packer, Roger J.; Ramesh, Vijaya; Riccardi, Vincent M.; Stevenson, David A.; Ullrich, Nicole J.; Upadhyaya, Meena; Stemmer-Rachamimov, Anat; Pediatrics, School of Medicine
    The Annual Children's Tumor Foundation International Neurofibromatosis Meeting is the premier venue for connecting discovery, translational and clinical scientists who are focused on neurofibromatosis types 1 and 2 (NF1 and NF2) and schwannomatosis (SWN). The meeting also features rare tumors such as glioma, meningioma, sarcoma, and neuroblastoma that occur both within these syndromes and spontaneously; associated with somatic mutations in NF1, NF2, and SWN. The meeting addresses both state of the field for current clinical care as well as emerging preclinical models fueling discovery of new therapeutic targets and discovery science initiatives investigating mechanisms of tumorigenesis. Importantly, this conference is a forum for presenting work in progress and bringing together all stakeholders in the scientific community. A highlight of the conference was the involvement of scientists from the pharmaceutical industry who presented growing efforts for rare disease therapeutic development in general and specifically, in pediatric patients with rare tumor syndromes. Another highlight was the focus on new investigators who presented new data about biomarker discovery, tumor pathogenesis, and diagnostic tools for NF1, NF2, and SWN. This report summarizes the themes of the meeting and a synthesis of the scientific discoveries presented at the conference in order to make the larger research community aware of progress in the neurofibromatoses.
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    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
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    The seventh international RASopathies symposium: Pathways to a cure-expanding knowledge, enhancing research, and therapeutic discovery
    (Wiley, 2022) Kontaridis, Maria I.; Roberts, Amy E.; Schill, Lisa; Schoyer, Lisa; Stronach, Beth; Andelfinger, Gregor; Aoki, Yoko; Axelrad, Marni E.; Bakker, Annette; Bennett, Anton M.; Broniscer, Alberto; Castel, Pau; Chang, Caitlin A.; Cyganek, Lukas; Das, Tirtha K.; den Hertog, Jeroen; Galperin, Emilia; Garg, Shruti; Gelb, Bruce D.; Gordon, Kristiana; Green, Tamar; Gripp, Karen W.; Itkin, Maxim; Kiuru, Maija; Korf, Bruce R.; Livingstone, Jeff R.; López-Juárez, Alejandro; Magoulas, Pilar L.; Mansour, Sahar; Milner, Theresa; Parker, Elisabeth; Pierpont, Elizabeth I.; Plouffe, Kevin; Rauen, Katherine A.; Shankar, Suma P.; Smith, Shane B.; Stevenson, David A.; Tartaglia, Marco; Van, Richard; Wagner, Morgan E.; Ware, Stephanie M.; Zenker, Martin; Pediatrics, School of Medicine
    RASopathies are a group of genetic disorders that are caused by genes that affect the canonical Ras/mitogen‐activated protein kinase (MAPK) signaling pathway. Despite tremendous progress in understanding the molecular consequences of these genetic anomalies, little movement has been made in translating these findings to the clinic. This year, the seventh International RASopathies Symposium focused on expanding the research knowledge that we have gained over the years to enhance new discoveries in the field, ones that we hope can lead to effective therapeutic treatments. Indeed, for the first time, research efforts are finally being translated to the clinic, with compassionate use of Ras/MAPK pathway inhibitors for the treatment of RASopathies. This biannual meeting, organized by the RASopathies Network, brought together basic scientists, clinicians, clinician scientists, patients, advocates, and their families, as well as representatives from pharmaceutical companies and the National Institutes of Health. A history of RASopathy gene discovery, identification of new disease genes, and the latest research, both at the bench and in the clinic, were discussed.