Primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD), also known as immotile cilia syndrome or Kartagener syndrome (when accompanied by situs inversus), is a rare inherited disorder affecting the structure and/or function of motile cilia — tiny hair-like projections that line the airways, middle ear, reproductive tract, and embryonic node. Defective ciliary motility leads to impaired mucociliary clearance in the respiratory tract, resulting in chronic and recurrent upper and lower respiratory infections. The hallmark clinical features include neonatal respiratory distress, chronic wet cough beginning in early childhood, recurrent sinusitis, chronic otitis media with effusion often leading to hearing impairment, and progressive bronchiectasis. Approximately 50% of individuals with PCD have situs inversus totalis (mirror-image reversal of internal organs), and a smaller subset may have heterotaxy with associated congenital heart defects, reflecting the role of nodal cilia in establishing left-right body asymmetry during embryonic development. PCD is caused by pathogenic variants in genes encoding ciliary structural proteins, assembly factors, or regulatory components. Over 50 causative genes have been identified to date, including DNAI1, DNAH5, DNAH11, CCDC39, CCDC40, and many others. The diagnosis is established through a combination of clinical suspicion, nasal nitric oxide measurement (characteristically very low in PCD), high-speed video microscopy of ciliary beat pattern, transmission electron microscopy of ciliary ultrastructure, immunofluorescence staining of ciliary proteins, and genetic testing. No single test is sufficient for diagnosis, and a multi-test approach is recommended. There is currently no cure for PCD, and no approved therapies specifically target the underlying ciliary defect. Management is largely supportive and borrows from cystic fibrosis care paradigms, focusing on aggressive airway clearance techniques (chest physiotherapy, exercise), prompt treatment of respiratory infections with antibiotics, and regular monitoring of lung function. Hearing aids may be needed for conductive hearing loss, and surgical interventions such as tympanostomy tubes or sinus surgery may be considered in selected cases. Fertility may be affected in both males (due to dysmotile sperm) and females (due to impaired ciliary function in the fallopian tubes), though assisted reproductive technologies can be successful. Early diagnosis and proactive management are essential to slow the progression of lung disease and preserve quality of life.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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