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Primary Ciliary Dyskinesia (PCD) is a rare, inherited, autosomal recessive disorder characterized by defective motility or ultrastructure of motile cilia, leading to impaired mucociliary clearance across the respiratory tract, middle ear, reproductive organs, and embryonic node.

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It encompasses Kartagener syndrome (PCD with situs inversus), but not all PCD patients have situs inversus.

Cytoskeleton and elastin disorders: Pathology review

Etiopathogenesis

Genetics

Autosomal recessive inheritance
Mutations in genes encoding ciliary structural proteins:
- DNAH5, DNAI1, CCDC39, CCDC40, etc.
Over 40 known causative genes (more than 75% genetically defined cases)

Pathophysiology: Dysfunctional or immotile cilia

Respiratory: impaired mucus clearance → recurrent infections
Embryonic: abnormal left-right axis development → situs abnormalities
Reproductive: sperm immotility (males), fallopian tube dysfunction (females)

Clinical Features

System	Manifestations
Respiratory	Neonatal respiratory distress (term infants), chronic cough, bronchiectasis, recurrent pneumonia
ENT	Chronic rhinosinusitis, recurrent otitis media, conductive hearing loss
Reproductive	Male infertility (immotile sperm); subfertility in females
Laterality defects	Situs inversus totalis (~50%), situs ambiguous, heterotaxy
Neonatal clue	Respiratory distress without risk factors, dextrocardia

![Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous, motile ciliopathy, characterized by neonatal respiratory distress, recurrent upper and lower respiratory tract infections, subfertility, and laterality defects. Diagnosis relies on a combination of tests for confirmation, including nasal nitric oxide (nNO) measurements, high-speed videomicroscopy analysis (HSVMA), immunofluorescent staining, axonemal ultrastructure analysis via transmission electron microscopy (TEM), and genetic testing. Notably, there is no single gold standard confirmatory or exclusionary test. Currently, 54 causative genes involved in cilia assembly, structure, and function have been linked to PCD; this rare disease has a spectrum of clinical manifestations and emerging genotype–phenotype relationships. In this review, we provide an overview of the structure and function of motile cilia, the emerging genetics and pathophysiology of this rare disease, as well as clinical features associated with motile ciliopathies, novel diagnostic tools, and updates on genotype–phenotype relationships in PCD.

Despotes KA, Zariwala MA, Davis SD, Ferkol TW. Primary Ciliary Dyskinesia: A Clinical Review. Cells. 2024; 13(11):974. https://doi.org/10.3390/cells13110974](attachment:e26569d8-c25f-4449-81d7-4091c38429c1:cells-13-00974-ag.png)

Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous, motile ciliopathy, characterized by neonatal respiratory distress, recurrent upper and lower respiratory tract infections, subfertility, and laterality defects. Diagnosis relies on a combination of tests for confirmation, including nasal nitric oxide (nNO) measurements, high-speed videomicroscopy analysis (HSVMA), immunofluorescent staining, axonemal ultrastructure analysis via transmission electron microscopy (TEM), and genetic testing. Notably, there is no single gold standard confirmatory or exclusionary test. Currently, 54 causative genes involved in cilia assembly, structure, and function have been linked to PCD; this rare disease has a spectrum of clinical manifestations and emerging genotype–phenotype relationships. In this review, we provide an overview of the structure and function of motile cilia, the emerging genetics and pathophysiology of this rare disease, as well as clinical features associated with motile ciliopathies, novel diagnostic tools, and updates on genotype–phenotype relationships in PCD.

Despotes KA, Zariwala MA, Davis SD, Ferkol TW. Primary Ciliary Dyskinesia: A Clinical Review. Cells. 2024; 13(11):974. https://doi.org/10.3390/cells13110974

Complications

Progressive bronchiectasis and respiratory failure