title: Heterozygous germline mutations in A2ML1 are associated with a disorder clinically related to Noonan syndrome.
abstract: Noonan syndrome (NS) is a developmental disorder characterized by short stature, facial dysmorphisms and congenital heart defects. To date, all mutations known to cause NS are dominant, activating mutations in signal transducers of the RAS/mitogen-activated protein kinase (MAPK) pathway. In 25% of cases, however, the genetic cause of NS remains elusive, suggesting that factors other than those involved in the canonical RAS/MAPK pathway may also have a role. Here, we used family-based whole exome sequencing of a case-parent trio and identified a de novo mutation, p.(Arg802His), in A2ML1, which encodes the secreted protease inhibitor α-2-macroglobulin (A2M)-like-1. Subsequent resequencing of A2ML1 in 155 cases with a clinical diagnosis of NS led to the identification of additional mutations in two families, p.(Arg802Leu) and p.(Arg592Leu). Functional characterization of these human A2ML1 mutations in zebrafish showed NS-like developmental defects, including a broad head, blunted face and cardiac malformations. Using the crystal structure of A2M, which is highly homologous to A2ML1, we identified the intramolecular interaction partner of p.Arg802. Mutation of this residue, p.Glu906, induced similar developmental defects in zebrafish, strengthening our conclusion that mutations in A2ML1 cause a disorder clinically related to NS. This is the first report of the involvement of an extracellular factor in a disorder clinically related to RASopathies, providing potential new leads for better understanding of the molecular basis of this family of developmental diseases.
authors.affiliation: 1] Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands [2] Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands [3] Donders Centre for Neuroscience, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Lisenka E L M
authors.initials: LE
authors.lastname: Vissers
authors.affiliation: Hubrecht Institute-KNAW and University Medical Center, Utrecht, The Netherlands.
authors.forename: Monica
authors.initials: M
authors.lastname: Bonetti
authors.affiliation: Hubrecht Institute-KNAW and University Medical Center, Utrecht, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Paardekooper Overman
authors.affiliation: Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Willy M
authors.initials: WM
authors.lastname: Nillesen
authors.affiliation: Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands.
authors.forename: Suzanna G M
authors.initials: SG
authors.lastname: Frints
authors.affiliation: 1] Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands [2] Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands [3] Donders Centre for Neuroscience, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Joep
authors.initials: J
authors.lastname: de Ligt
authors.affiliation: Dipartimento di Pediatria, Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zampino
authors.affiliation: IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Justino
authors.affiliation: IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.
authors.forename: José C
authors.initials: JC
authors.lastname: Machado
authors.affiliation: Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Marga
authors.initials: M
authors.lastname: Schepens
authors.affiliation: 1] Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands [2] Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands [3] Donders Centre for Neuroscience, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Han G
authors.initials: HG
authors.lastname: Brunner
authors.affiliation: 1] Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands [2] Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands [3] Donders Centre for Neuroscience, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Joris A
authors.initials: JA
authors.lastname: Veltman
authors.affiliation: Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: Scheffer
authors.affiliation: Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Utrecht, the Netherlands.
authors.forename: Piet
authors.initials: P
authors.lastname: Gros
authors.affiliation: IPATIMUP - Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.
authors.forename: José L
authors.identifier: 0000000171324094
authors.initials: JL
authors.lastname: Costa
authors.affiliation: Dipartimento di Ematologia, Oncologia e Medicina Molecolare, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Tartaglia
authors.affiliation: Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Ineke
authors.initials: I
authors.lastname: van der Burgt
authors.affiliation: 1] Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands [2] Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Helger G
authors.initials: HG
authors.lastname: Yntema
authors.affiliation: 1] Hubrecht Institute-KNAW and University Medical Center, Utrecht, The Netherlands [2] Institute of Biology, Leiden, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: den Hertog
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D004252:DNA Mutational Analysis; D059472:Exome; D019066:Facies; D005260:Female; D015870:Gene Expression; D018095:Germ-Line Mutation; D006579:Heterozygote; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008297:Male; D008958:Models, Molecular; D009154:Mutation; D009634:Noonan Syndrome / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D011487:Protein Conformation; D015027:Zebrafish; D000511:alpha-Macroglobulins / Q000737:chemistry / Q000235:genetics*
chemical_list: C510358:A2ML1 protein, human; D000511:alpha-Macroglobulins