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Hjeij R, Aprea I, Poeta M, Nöthe-Menchen T, Bracht D, Raidt J, Honecker BI, Dougherty GW, Olbrich H, Schwartz O, Keller U, Nüsse H, Diderich KEM, Vogelberg C, Santamaria F, Omran H. Pathogenic variants in CLXN encoding the outer dynein arm docking-associated calcium-binding protein calaxin cause primary ciliary dyskinesia. Genet Med 2023; 25:100798. [PMID: 36727596 DOI: 10.1016/j.gim.2023.100798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/24/2023] [Accepted: 01/24/2023] [Indexed: 02/03/2023] Open
Abstract
PURPOSE Primary ciliary dyskinesia (PCD) is a heterogeneous disorder that includes respiratory symptoms, laterality defects, and infertility caused by dysfunction of motile cilia. Most PCD-causing variants result in abnormal outer dynein arms (ODAs), which provide the generative force for respiratory ciliary beating and proper mucociliary clearance. METHODS In addition to studies in mouse and planaria, clinical exome sequencing and functional analyses in human were performed. RESULTS In this study, we identified homozygous pathogenic variants in CLXN (EFCAB1/ODAD5) in 3 individuals with laterality defects and respiratory symptoms. Consistently, we found that Clxn is expressed in mice left-right organizer. Transmission electron microscopy depicted ODA defects in distal ciliary axonemes. Immunofluorescence microscopy revealed absence of CLXN from the ciliary axonemes, absence of the ODA components DNAH5, DNAI1, and DNAI2 from the distal axonemes, and mislocalization or absence of DNAH9. In addition, CLXN was undetectable in ciliary axonemes of individuals with defects in the ODA-docking machinery: ODAD1, ODAD2, ODAD3, and ODAD4. Furthermore, SMED-EFCAB1-deficient planaria displayed ciliary dysmotility. CONCLUSION Our results revealed that pathogenic variants in CLXN cause PCD with defects in the assembly of distal ODAs in the respiratory cilia. CLXN should be referred to as ODA-docking complex-associated protein ODAD5.
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Affiliation(s)
- Rim Hjeij
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Isabella Aprea
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Marco Poeta
- Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy
| | - Tabea Nöthe-Menchen
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Diana Bracht
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Johanna Raidt
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Barbara I Honecker
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Gerard W Dougherty
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Heike Olbrich
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Oliver Schwartz
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany
| | - Ulrike Keller
- Institute of Medical Physics and Biophysics, University of Muenster, Muenster, Germany
| | - Harald Nüsse
- Institute of Medical Physics and Biophysics, University of Muenster, Muenster, Germany
| | | | - Christian Vogelberg
- Pediatric Department, University Hospital Carl Gustav Carus Dresden, Technical University Dresden, Dresden, Germany
| | - Francesca Santamaria
- Department of Translational Medical Sciences, University of Naples Federico II, Naples, Italy
| | - Heymut Omran
- Department of General Pediatrics, University Hospital Muenster, Muenster, Germany.
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