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  • Skewed X-chromosome inactivation drives the proportion of DNAAF6-defective airway motile cilia and variable expressivity in primary ciliary dyskinesia

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Epigenetics
Original research
Skewed X-chromosome inactivation drives the proportion of DNAAF6-defective airway motile cilia and variable expressivity in primary ciliary dyskinesia
  1. Lucie Thomas1,
  2. Laurence Cuisset2,
  3. Jean-Francois Papon3,4,
  4. Aline Tamalet5,
  5. Isabelle Pin6,
  6. Rola Abou Taam7,
  7. Catherine Faucon8,
  8. Guy Montantin9,
  9. Sylvie Tissier9,
  10. Philippe Duquesnoy1,
  11. Florence Dastot - Le Moal9,
  12. Bruno Copin1,9,
  13. Nathalie Carion2,
  14. Bruno Louis4,
  15. Sandra Chantot-Bastaraud1,10,
  16. Jean-Pierre Siffroi1,10,
  17. Rana Mitri8,
  18. André Coste4,11,
  19. Estelle Escudier1,9,
  20. Guillaume Thouvenin5,
  21. Serge Amselem1,9,
  22. Marie Legendre1,9
  1. 1 Childhood Genetic Diseases, Sorbonne Université, Inserm, Hôpital Armand-Trousseau, Paris, F-75012, France
  2. 2 Service de Médecine Génomique, Assistance Publique Hôpitaux de Paris (AP-HP), Université de Paris, Hôpital Cochin, Paris, F-75014, France
  3. 3 Service d’Oto-Rhino-Laryngologie et de Chirurgie Cervico-Faciale, AP-HP, Hôpital Bicêtre, Le Kremlin-Bicêtre, F-94270, France
  4. 4 Institut Mondor de Recherche Biomédicale, Université Paris-Est Créteil, Inserm U955, CNRS ERL7240, Hôpital Henri-Mondor, Créteil, F-94010, France
  5. 5 Département de Pneumologie Pédiatrique, Centre National de Référence des Maladies Respiratoires Rares RespiRare, AP-HP, Sorbonne Université, Hôpital Armand-Trousseau Hospital, Paris, F-75012, France
  6. 6 Pédiatrie, CHU Grenoble Alpes, Grenoble, F-38500, France
  7. 7 Service de Pneumologie et Allergologie Pédiatriques, AP-HP, Hôpital Necker-Enfants Malades, Paris, F-75015, France
  8. 8 Service d'Anatomopathologie, Laboratoire de Microscopie Electronique, Centre Hospitalier Intercommunal de Créteil, Créteil, F-94000, France
  9. 9 Génétique moléculaire, AP-HP, Hôpital Armand-Trousseau, Paris, F-75012, Paris
  10. 10 Génétique chromosomique, AP-HP, Hôpital Trousseau, Paris, F-75012, France
  11. 11 Service d’ORL et de Chirurgie Cervico-Faciale, AP-HP, Hôpital Henri-Mondor, Centre Hospitalier Intercommunal de Créteil, Créteil, F-94000, France
  1. Correspondence to Dr Marie Legendre, UF de Génétique Moléculaire, Hôpital Armand-Trousseau, APHP, Paris 75012, Île-de-France, France; marie.legendre{at}aphp.fr

Abstract

Background Primary ciliary dyskinesia (PCD) is a rare airway disorder caused by defective motile cilia. Only male patients have been reported with pathogenic mutations in X-linked DNAAF6, which result in the absence of ciliary dynein arms, whereas their heterozygous mothers are supposedly healthy. Our objective was to assess the possible clinical and ciliary consequences of X-chromosome inactivation (XCI) in these mothers.

Methods XCI patterns of six mothers of male patients with DNAAF6-related PCD were determined by DNA-methylation studies and compared with their clinical phenotype (6/6 mothers), as well as their ciliary phenotype (4/6 mothers), as assessed by immunofluorescence and high-speed videomicroscopy analyses. The mutated X chromosome was tracked to assess the percentage of cells with a normal inactivated DNAAF6 allele.

Results The mothers’ phenotypes ranged from absence of symptoms to mild/moderate or severe airway phenotypes, closely reflecting their XCI pattern. Analyses of the symptomatic mothers’ airway ciliated cells revealed the coexistence of normal cells and cells with immotile cilia lacking dynein arms, whose ratio closely mirrored their XCI pattern.

Conclusion This study highlights the importance of searching for heterozygous pathogenic DNAAF6 mutations in all female relatives of male PCD patients with a DNAAF6 defect, as well as in females consulting for mild chronic respiratory symptoms. Our results also demonstrate that about one-third—ranging from 20% to 50%—normal ciliated airway cells sufficed to avoid severe PCD, a result paving the way for gene therapy.

  • X-Linked Genetic Diseases
  • Respiratory Tract Diseases

Data availability statement

All data relevant to the study are included in the article or uploaded as supplementary information.

https://doi.org/10.1136/jmg-2023-109700

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    Data availability statement

    All data relevant to the study are included in the article or uploaded as supplementary information.

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    Footnotes

    • Contributors LT contributed in the study design, acquisition and analysis of data, and writing the manuscript. LC analysed methylation-sensitive digestion experiments and participated to the manuscript review. JFP was involved in the acquisition of clinical data, the follow-up of the investigated mothers and the nasal brushing samples. AT, IP, GT and AC were involved in the acquisition of clinical data and follow-up of the investigated mothers. RAT participated in clinical phenotyping of mothers. CF conducted all TEM experiments. GM, ST, PD, FDLM and BC performed genetic analyses. NC performed methylation-sensitive digestion experiments. BL developed and provided the HSVA software. SC conducted the acquisition and analysis of copy-number-variation data. RM was involved in TEM analyses and data interpretation. EE participated in the study conception and design, the interpretation of data and in writing and review the manuscript. SA was involved in the study conception, the analysis of the data, the redaction and the final approval of the manuscript. ML conceived the study and contributed to study design, participated to the analysis of the data, the redaction and final approval of the manuscript, and acts as a guarantor. All authors revised the manuscript and gave their final approval.

    • Funding This work was supported by the Institut National de la Santé et de la Recherche Médicale, the Fondation pour la Recherche Médicale and the Legs Poix from the Chancellerie des Universités.

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.