2. Academic Validation
  3. SPRED2 loss-of-function causes a recessive Noonan syndrome-like phenotype

SPRED2 loss-of-function causes a recessive Noonan syndrome-like phenotype

  • Am J Hum Genet. 2021 Nov 4;108(11):2112-2129. doi: 10.1016/j.ajhg.2021.09.007.
Marialetizia Motta 1,  Giulia Fasano 1,  Sina Gredy 2,  Julia Brinkmann 3,  Adeline Alice Bonnard 4,  Pelin Ozlem Simsek-Kiper 5,  Elif Yilmaz Gulec 6,  Leila Essaddam 7,  Gulen Eda Utine 5,  Ingrid Guarnetti Prandi 8,  Martina Venditti 1,  Francesca Pantaleoni 1,  Francesca Clementina Radio 1,  Andrea Ciolfi 1,  Stefania Petrini 9,  Federica Consoli 10,  Cédric Vignal 11,  Denis Hepbasli 2,  Melanie Ullrich 2,  Elke de Boer 12,  Lisenka E L M Vissers 12,  Sami Gritli 13,  Cesare Rossi 14,  Alessandro De Luca 10,  Saayda Ben Becher 7,  Bruce D Gelb 15,  Bruno Dallapiccola 1,  Antonella Lauri 1,  Giovanni Chillemi 16,  Kai Schuh 2,  Hélène Cavé 4,  Martin Zenker 3,  Marco Tartaglia 17
Affiliations

Affiliations

  • 1 Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy.
  • 2 Institute of Physiology, University of Wuerzburg, 97070 Wuerzburg, Germany.
  • 3 Institute of Human Genetics, University Hospital Magdeburg, 39120 Magdeburg, Germany.
  • 4 Assistance Publique des Hôpitaux de Paris (AP-HP), Hôpital Robert Debré, Département de Génétique, 75019 Paris, France; INSERM UMR 1131, Institut de Recherche Saint-Louis, Université de Paris, Paris, France.
  • 5 Department of Pediatric Genetics, Hacettepe University Faculty of Medicine, Sihhiye, 06100 Ankara, Turkey.
  • 6 Department of Medical Genetics, Health Sciences University, Istanbul Kanuni Sultan Suleyman Training and Research Hospital, 34303 Istanbul, Turkey.
  • 7 Department of Pediatrics-PUC, Béchir Hamza Children's Hospital, Faculty of Medicine, University of Tunis El Manar, Jebbari 1007, Tunis, Tunisia.
  • 8 Dipartimento per la Innovazione nei Sistemi Biologici, Agroalimentari e Forestali, Università Della Tuscia, 01100 Viterbo, Italy.
  • 9 Confocal Microscopy Core Facility, Ospedale Pediatrico Bambino Gesù, 00146 Rome, Italy.
  • 10 Medical Genetics Division, Fondazione IRCCS Casa Sollievo della Sofferenza, 71013 San Giovanni Rotondo, Italy.
  • 11 Assistance Publique des Hôpitaux de Paris (AP-HP), Hôpital Robert Debré, Département de Génétique, 75019 Paris, France.
  • 12 Department of Human Genetics, Radboudumc, 6525 GA Nijmegen, the Netherlands; Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6525 GA Nijmegen, the Netherlands.
  • 13 Department of Immunology, Pasteur Institute of Tunis, 1002 Tunis-Belvédère, Tunisia.
  • 14 Genetica Medica, IRCCS Azienda Ospedaliero-Universitaria di Bologna, 40138 Bologna, Italy.
  • 15 Mindich Child Health and Development Institute and Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
  • 16 Dipartimento per la Innovazione nei Sistemi Biologici, Agroalimentari e Forestali, Università Della Tuscia, 01100 Viterbo, Italy; Istituto di Biomembrane, Bioenergetica e Biotecnologie Molecolari, Centro Nazionale Delle Ricerche, 70126 Bari, Italy.
  • 17 Genetics and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesù, IRCCS, 00146 Rome, Italy. Electronic address: [email protected].
PMID: 34626534 DOI: 10.1016/j.ajhg.2021.09.007
Abstract

Upregulated signal flow through Ras and the mitogen-associated protein kinase (MAPK) cascade is the unifying mechanistic theme of the RASopathies, a family of disorders affecting development and growth. Pathogenic variants in more than 20 genes have been causally linked to RASopathies, the majority having a dominant role in promoting enhanced signaling. Here, we report that SPRED2 loss of function is causally linked to a recessive phenotype evocative of Noonan syndrome. Homozygosity for three different variants-c.187C>T (p.Arg63∗), c.299T>C (p.Leu100Pro), and c.1142_1143delTT (p.Leu381Hisfs∗95)-were identified in four subjects from three families. All variants severely affected protein stability, causing accelerated degradation, and variably perturbed SPRED2 functional behavior. When overexpressed in cells, all variants were unable to negatively modulate EGF-promoted RAF1, MEK, and ERK phosphorylation, and time-course experiments in primary fibroblasts (p.Leu100Pro and p.Leu381Hisfs∗95) documented an increased and prolonged activation of the MAPK cascade in response to EGF stimulation. Morpholino-mediated knockdown of spred2a and spred2b in zebrafish induced defects in convergence and extension cell movements indicating upregulated RAS-MAPK signaling, which were rescued by expressing wild-type SPRED2 but not the SPRED2Leu381Hisfs∗95 protein. The clinical phenotype of the four affected individuals included developmental delay, intellectual disability, cardiac defects, short stature, skeletal anomalies, and a typical facial gestalt as major features, without the occurrence of the distinctive skin signs characterizing Legius syndrome. These features, in part, characterize the phenotype of Spred2-/- mice. Our findings identify the second recessive form of Noonan syndrome and document pleiotropic consequences of SPRED2 loss of function in development.

Keywords

Legius syndrome; MAPK; Noonan syndrome; RAS; RASopathies; SPRED; SPRED1; SPRED2; neurofibromatosis; neurofibromin.

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