1. Autoimmunity and immunodeficiency associated with monoallelic LIG4 mutations via haploinsufficiency
- Author
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Annaïse J. Jauch, Olivier Bignucolo, Sayuri Seki, Marie Ghraichy, Ottavia M. Delmonte, Valentin von Niederhäusern, Rebecca Higgins, Adhideb Ghosh, Masako Nishizawa, Mariko Tanaka, Adrian Baldrich, Julius Köppen, Julia R. Hirsiger, Robin Hupfer, Stephan Ehl, Anne Rensing-Ehl, Helmut Hopfer, Spasenija Savic Prince, Stephen R. Daley, Florian A. Marquardsen, Benedikt J. Meyer, Michael Tamm, Thomas D. Daikeler, Tamara Diesch, Thomas Kühne, Arthur Helbling, Caroline Berkemeier, Ingmar Heijnen, Alexander A. Navarini, Johannes Trück, Jean-Pierre de Villartay, Annette Oxenius, Christoph T. Berger, Christoph Hess, Luigi D. Notarangelo, Hiroyuki Yamamoto, and Mike Recher
- Subjects
Immunology ,Immunology and Allergy ,610 Medicine & health - Abstract
BACKGROUND Biallelic mutations in LIG4 encoding DNA-ligase 4 cause a rare immunodeficiency syndrome manifesting as infant-onset life-threatening and/or opportunistic infections, skeletal malformations, radiosensitivity and neoplasia. LIG4 is pivotal during DNA repair and during V(D)J recombination as it performs the final DNA-break sealing step. OBJECTIVE We explored whether monoallelic LIG4 missense mutations may underlie immunodeficiency and autoimmunity with autosomal dominant inheritance. METHODS Extensive flow-cytometric immune-phenotyping was performed. Rare variants of immune system genes were analyzed by whole exome sequencing. DNA repair functionality and T cell-intrinsic DNA damage tolerance was tested with an ensemble of in vitro and in silico tools. Antigen-receptor diversity and autoimmune features were characterized by high-throughput sequencing and autoantibody arrays. Reconstitution of wild-type vs. mutant LIG4 were performed in LIG4 knock-out Jurkat T cells and DNA damage tolerance was subsequently assessed. RESULTS A novel heterozygous LIG4 loss-of-function mutation (p.R580Q), associated with a dominantly inherited familial immune-dysregulation consisting of autoimmune cytopenias, and in the index patient with lymphoproliferation, agammaglobulinemia and adaptive immune cell infiltration into nonlymphoid organs. Immunophenotyping revealed reduced naïve CD4+ T cells and low TCR-Vα7.2+ T cells, while T/B-cell receptor repertoires showed only mild alterations. Cohort screening identified two other non-related patients with the monoallelic LIG4 mutation p.A842D recapitulating clinical and immune-phenotypic dysregulations observed in the index family and displaying T cell-intrinsic DNA damage intolerance. Reconstitution experiments and molecular dynamics simulations categorize both missense mutations as loss-of-function and haploinsufficient. CONCLUSION We provide evidence that certain monoallelic LIG4 mutations may cause human immune dysregulation via haploinsufficiency.
- Published
- 2023
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