Primary ciliary dyskinesia

Rare autosomal recessive genetic disorder affecting ciliary function

Primary ciliary dyskinesia
Synonyms	PCD, Immotile cilia syndrome (outdated)
Pronounce	N/A
Specialty	N/A
Symptoms	Chronic respiratory infections, sinusitis, otitis media, bronchiectasis, infertility
Complications	Chronic lung disease, bronchiectasis, infertility, hearing loss
Onset	Early childhood
Duration	Lifelong
Types	N/A
Causes	Genetic mutations affecting ciliary function
Risks	Family history, autosomal recessive inheritance
Diagnosis	Genetic testing, nasal nitric oxide testing, ciliary biopsy, imaging studies
Differential diagnosis	Cystic fibrosis, Bronchiectasis, Asthma, Kartagener syndrome
Prevention	Genetic counseling
Treatment	Chest physiotherapy, antibiotics, supportive care, surgical interventions
Medication	Antibiotics, mucolytics
Prognosis	Variable; good management can improve quality of life
Frequency	Approximately 1 in 10,000 to 1 in 20,000 births
Deaths	N/A

Primary ciliary dyskinesia (PCD) is a rare, ciliopathic autosomal recessive genetic disorder characterized by abnormal function of cilia, the microscopic hair-like structures lining various organs such as the respiratory tract, sinuses, Eustachian tube, middle ear, and reproductive organs. Historically termed "immotile cilia syndrome," the term is no longer preferred, as the cilia retain movement, although their action is typically inefficient or unsynchronized.

Pathophysiology

PCD is caused by genetic mutations that affect the structure and function of motile cilia. Normally, these cilia beat synchronously 7 to 22 times per second, facilitating mucus clearance through the mucociliary escalator. Dysfunctional cilia result in impaired mucus clearance, causing recurrent infections and chronic inflammation.

Signs and symptoms

CT scan demonstrating bronchiectasis in PCD (Kartagener syndrome)

Sagittal CT showing cylindrical bronchiectasis in lower lung lobes in PCD patient

The primary symptoms of PCD result from impaired mucus clearance and chronic respiratory infections. Symptoms usually begin early in childhood and can include:

• Chronic cough with excessive mucus production
• Recurrent sinusitis and nasal congestion
• Frequent ear infections (otitis media) leading to potential hearing loss
• Recurrent bronchitis and pneumonia
• Progressive development of bronchiectasis—permanent dilation and damage to the airways
• Reduced lung function over time

Non-respiratory symptoms include:

• Infertility due to impaired ciliary function in the reproductive tract:

Male infertility related to immotile sperm flagella Female infertility or increased risk of ectopic pregnancy due to impaired cilia in the fallopian tubes

Kartagener syndrome

Approximately 50% of patients with PCD have a subset of the condition known as Kartagener syndrome, characterized by the clinical triad of:

• Primary ciliary dyskinesia
• Situs inversus (mirror-image reversal of internal organs)
• Chronic sinusitis

Genetics

PCD is inherited in an autosomal recessive manner, requiring two copies of the defective gene—one from each parent. Numerous genes have been implicated, including DNAI1, DNAH5, and others involved in the structure and function of ciliary dynein arms and associated proteins.

Diagnosis

Diagnosing PCD can be challenging due to overlapping symptoms with other respiratory conditions such as asthma, bronchiectasis, and cystic fibrosis. Diagnostic methods include:

• Clinical evaluation: Chronic respiratory symptoms starting early in childhood.
• Nasal nitric oxide testing: Levels typically very low in patients with PCD.
• Genetic testing: Identifies specific genetic mutations associated with PCD.
• High-speed videomicroscopy: Examination of ciliary beat frequency and coordination from nasal or bronchial biopsy samples.
• Electron microscopy: Detects structural abnormalities in cilia.
• Imaging: Chest X-ray and CT scans may demonstrate characteristic findings like bronchiectasis or mucus plugging.

Differential diagnosis

Conditions presenting similarly to PCD include:

• Cystic fibrosis
• Bronchiectasis from other causes
• Severe, chronic asthma
• Immunodeficiency disorders
• Allergic bronchopulmonary aspergillosis (ABPA)

Management and treatment

PCD has no cure, but management focuses on preventing complications and reducing symptom severity:

Chest physiotherapy

Daily airway clearance techniques help remove mucus, reducing infection frequency and preserving lung function:

• Postural drainage
• Chest percussion and vibration
• Active breathing techniques
• Use of mechanical mucus clearance devices

Medication

Pharmacologic management includes:

• Antibiotics for frequent respiratory infections, including prophylactic or intermittent courses.
• Mucolytics to decrease mucus viscosity (e.g., hypertonic saline inhalation).
• Bronchodilators, if airway hyperreactivity is present.

Surgical intervention

Surgery may be necessary for:

• Chronic sinusitis (e.g., endoscopic sinus surgery).
• Severe bronchiectasis complications.
• Placement of ventilation tubes in cases of chronic ear infections.

Fertility assistance

Patients experiencing infertility may benefit from assisted reproductive techniques such as in vitro fertilization (IVF).

Prognosis

PCD is a chronic, lifelong condition. Early diagnosis and aggressive management of infections and airway clearance can significantly improve quality of life and slow disease progression. Without appropriate management, PCD can result in severe lung damage and reduced lifespan.

Epidemiology

Primary ciliary dyskinesia is rare, affecting approximately 1 in 10,000 to 1 in 20,000 births globally. Prevalence may be higher in populations with increased consanguinity.

Research

Research continues to explore gene-specific therapies and advanced diagnostic techniques to improve outcomes and quality of life for individuals with PCD. Studies on nitric oxide pathways and ciliary biology provide insights into novel therapeutic approaches.

Gallery

• 
  CT scan showing mucus impaction ("tree-in-bud")
• 
  Bronchiectasis associated with Kartagener syndrome
• 
  Cylindrical bronchiectasis in lower lobes

See also

• Kartagener syndrome
• Bronchiectasis
• Ciliopathy
• Situs inversus

External links

• Primary Ciliary Dyskinesia Foundation
• Genetic and Rare Diseases Information Center (GARD)

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