2. Academic Validation
  3. Homozygous DBF4 mutation as a cause for severe congenital neutropenia

Homozygous DBF4 mutation as a cause for severe congenital neutropenia

  • J Allergy Clin Immunol. 2023 Feb 23;S0091-6749(23)00230-0. doi: 10.1016/j.jaci.2023.02.016.
Mathijs Willemsen 1,  John S Barber 1,  Erika Van Nieuwenhove 2,  Frederik Staels 3,  Margaux Gerbaux 4,  Julika Neumann 1,  Teresa Prezzemolo 1,  Emanuela Pasciuto 1,  Vasiliki Lagou 1,  Nancy Boeckx 5,  Jessica Filtjens 6,  Amber De Visscher 6,  Patrick Matthys 6,  Rik Schrijvers 7,  Thomas Tousseyn 8,  Mark O'Driscoll 9,  Giorgia Bucciol 10,  Susan Schlenner 11,  Isabelle Meyts 12,  Stephanie Humblet-Baron 13,  Adrian Liston 14
Affiliations

Affiliations

  • 1 Department of Microbiology, Immunology and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium.
  • 2 Department of Microbiology, Immunology and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium; Department of Pediatrics, University Hospitals Leuven, Leuven, Belgium.
  • 3 Department of Microbiology, Immunology and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium.
  • 4 Department of Microbiology, Immunology and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; Pediatric Department, Academic Children Hospital Queen Fabiola, Université Libre de Bruxelles, Brussels, Belgium.
  • 5 Department of Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium.
  • 6 Department of Microbiology, Immunology and Transplantation, Laboratory of Immunobiology, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium.
  • 7 Department of Microbiology, Immunology and Transplantation, Allergy and Clinical Immunology Research Group, KU Leuven, Leuven, Belgium.
  • 8 Department of Pathology, University Hospitals Leuven, Leuven, Belgium.
  • 9 Human DNA Damage Response Disorders Group, Genome Damage and Stability Centre, University of Sussex, Brighton, BN1 9RQ, United Kingdom.
  • 10 Department of Microbiology, Immunology and Transplantation, Laboratory for Inborn Errors of Immunity, KU Leuven, Leuven, Belgium; Department of Pediatrics, Division of Primary Immunodeficiencies, University Hospitals Leuven, Leuven, Belgium.
  • 11 Department of Microbiology, Immunology and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium.
  • 12 Department of Microbiology, Immunology and Transplantation, Laboratory for Inborn Errors of Immunity, KU Leuven, Leuven, Belgium; Department of Pediatrics, Division of Primary Immunodeficiencies, University Hospitals Leuven, Leuven, Belgium; ERN-RITA Core Center Member.
  • 13 Department of Microbiology, Immunology and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium. Electronic address: [email protected].
  • 14 Department of Microbiology, Immunology and Transplantation, Laboratory of Adaptive Immunity, KU Leuven, Leuven, Belgium; VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium; Immunology Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT United Kingdom. Electronic address: [email protected].
PMID: 36841265 DOI: 10.1016/j.jaci.2023.02.016
Abstract

Background: Severe congenital neutropenia presents with recurrent infections early in life due to arrested granulopoiesis. Multiple genetic defects are known to block granulocyte differentiation, however a genetic cause remains unknown in approximately 40% of cases.

Objective: We aimed to characterize a patient with severe congenital neutropenia and syndromic features without a genetic diagnosis.

Methods: Whole exome sequencing results were validated using flow cytometry, Western blotting, co-immunoprecipitation, quantitative PCR, cell cycle and proliferation analysis of lymphocytes and fibroblasts and granulocytic differentiation of primary CD34+ and HL-60 cells.

Results: We identified a homozygous missense mutation in DBF4 in a patient with mild extra-uterine growth retardation, facial dysmorphism and severe congenital neutropenia. DBF4 is the regulatory subunit of the CDC7 kinase, together known as DBF4-dependent kinase (DDK), the complex essential for DNA replication initiation. The variant allele demonstrated impaired ability to bind CDC7, resulting in decreased DDK-mediated phosphorylation, defective S phase entry and progression and impaired differentiation of granulocytes associated with activation of the p53-p21 pathway. The introduction of WT DBF4 into patient CD34+ cells rescued the promyelocyte differentiation arrest.

Conclusion: Hypomorphic DBF4 mutation causes autosomal recessive severe congenital neutropenia with syndromic features.

Keywords

DBF4; DNA replication; facial dysmorphism; genetics; inborn errors of immunity; mutation; neutropenia; perturbed growth; primary immunodeficiency.

Figures
Products
  • Cat. No.
    Product Name
    Description
    Target
    Research Area
  • HY-100888
    99.07%, CDC7 Inhibitor