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
  • 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.
Products