Presence of Genetic Variants Among Young Men With Severe COVID-19

Caspar I. van der Made, Annet Simons, Janneke Schuurs-Hoeijmakers, Guus van den Heuvel, Tuomo Mantere, Simone Kersten, Rosanne C. van Deuren, Marloes Steehouwer, Simon V. van Reijmersdal, Martin Jaeger, Tom Hofste, Galuh Astuti, Jordi Corominas Galbany, Vyne van der Schoot, Hans van der Hoeven, Wanda Hagmolen Of ten Have, Eva Klijn, Catrien van den Meer, Jeroen Fiddelaers, Quirijn de MastChantal P. Bleeker-Rovers, Leo A. B. Joosten, Helger G. Yntema, Christian Gilissen, Marcel Nelen, Jos W. M. van der Meer, Han G. Brunner, Mihai G. Netea, Frank L. van de Veerdonk, Alexander Hoischen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


This case series describes rare putative X-chromosomal loss-of-function variants associated with impaired peripheral mononuclear blood cell interferon signaling in 4 young male patients hospitalized with severe coronavirus disease 2019 (COVID-19) in the Netherlands.

Question Are genetic variants associated with severe coronavirus disease 2019 (COVID-19) in young male patients? Findings In a case series that included 4 young male patients with severe COVID-19 from 2 families, rare loss-of-function variants of the X-chromosomal TLR7 were identified, with immunological defects in type I and II interferon production. Meaning These findings provide insights into the pathogenesis of COVID-19.

Importance Severe coronavirus disease 2019 (COVID-19) can occur in younger, predominantly male, patients without preexisting medical conditions. Some individuals may have primary immunodeficiencies that predispose to severe infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Objective To explore the presence of genetic variants associated with primary immunodeficiencies among young patients with COVID-19. Design, Setting, and Participants Case series of pairs of brothers without medical history meeting the selection criteria of young (age T; p.[Val795Phe]). In primary peripheral blood mononuclear cells from the patients, downstream type I interferon (IFN) signaling was transcriptionally downregulated, as measured by significantly decreased mRNA expression of IRF7, IFNB1, and ISG15 on stimulation with the TLR7 agonist imiquimod as compared with family members and controls. The production of IFN-gamma, a type II IFN, was decreased in patients in response to stimulation with imiquimod. Conclusions and Relevance In this case series of 4 young male patients with severe COVID-19, rare putative loss-of-function variants of X-chromosomal TLR7 were identified that were associated with impaired type I and II IFN responses. These preliminary findings provide insights into the pathogenesis of COVID-19.

Original languageEnglish
Pages (from-to)663-673
Number of pages11
JournalJAMA-Journal of the American Medical Association
Issue number7
Publication statusPublished - 18 Aug 2020


  • SARS-COV-2
  • SARS

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