Primary Ciliary Dyskinesia

Overview

Definition

Primary ciliary dyskinesia (PCD) is a genetic condition in which cilia in the respiratory tract have defective functionality that leads to ineffective mucociliary clearance.

Epidemiology

• Affects 1 in 16,000–20,000 live births 
• Equal prevalence in men and women
• Affects all racial and ethnic groups

Etiology

• Autosomal recessive inheritance
• More than 30 different PCD genetic variants have been implicated.

Pathophysiology

Normal physiology

• Cilia are microscopic, finger-like structures projecting out of the cell surface.
• Cilia line the airways, reproductive tissues, and other organs.
• Normal, motile cilia in the upper and lower respiratory tract are composed of:
  • Alpha- and beta-tubulin monomers
  • A complex central core (axonemal) structure including:
    • Dynein arms
    • Radial spokes
    • Nexin links
• Cilia usually beat in a coordinated fashion to move respiratory secretions.

Ciliary dysfunction

• PCD is a highly heterogeneous syndrome that can be caused by a defect in:
  • 1 of the many polypeptide species in the central core of the cilia 
  • Proteins needed for the proper assembly of cilia
• Mutations involving dynein are commonly implicated in PCD.
• Effects:
  • Abnormal ciliary movement (ciliary dyskinesia)
  • Inability to move (ciliary immobility)
  • Absent cilia (ciliary aplasia)
• Proper ciliary function is necessary for the rotation of organs in the abdomen and chest.
• With dysfunction, situs inversus and/or abnormal organ positioning can occur.

Clinical Presentation

Onset

• Commonly presents in children, but can also present in adults
• Median age of diagnosis:
  • In children, 5–5.5 years of age
  • In adults, 22 years of age

Signs and symptoms

• Recurrent infections of the upper and lower respiratory tract:
  • Most common symptom
  • Common causative bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview include:
    • Haemophilus Haemophilus Haemophilus is a genus of Gram-negative coccobacilli, all of whose strains require at least 1 of 2 factors for growth (factor V [NAD] and factor X [heme]); therefore, it is most often isolated on chocolate agar, which can supply both factors. The pathogenic species are H. influenzae and H. ducreyi. Haemophilus influenzae
    • Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus pneumoniae
    • Staphylococcus Staphylococcus Staphylococcus is a medically important genera of Gram-positive, aerobic cocci. These bacteria form clusters resembling grapes on culture plates. Staphylococci are ubiquitous for humans, and many strains compose the normal skin flora. Staphylococcus aureus
    • Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas aeruginosa
    • Non- tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis mycobacteria Mycobacteria Mycobacterium is a genus of the family Mycobacteriaceae in the phylum Actinobacteria. Mycobacteria comprise more than 150 species of facultative intracellular bacilli that are mostly obligate aerobes. Mycobacteria are responsible for multiple human infections including serious diseases, such as tuberculosis (M. tuberculosis), leprosy (M. leprae), and M. avium complex infections. Mycobacterium
• Chronic rhinosinusitis:
  • Occurs in almost 100% of patients
  • Year-round runny nose Nose The nose is the human body's primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Anatomy of the Nose and nasal congestion
  • Often begins in early childhood
  • Usually involves the maxillary and ethmoid sinuses
  • Can be associated with headaches
  • Can lead to nasal polyposis
• Mild respiratory distress (in newborns):
  • Tachypnea 
  • Hypoxemia
• Bronchiectasis: 
  • Auscultatory crackles
  • Wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing that mimics asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma
• Chronic secretory otitis media with recurrent bouts of acute otitis media Acute Otitis Media Acute otitis media is an infection in the middle ear characterized by mucosal inflammation and retention of fluid. The most common pathogens are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. The condition can present with fever, otalgia, and diminished hearing. Acute Otitis Media (↓ frequency after puberty Puberty Puberty is a complex series of physical, psychosocial, and cognitive transitions usually experienced by adolescents (11-19 years of age). Puberty is marked by a growth in stature and the development of secondary sexual characteristics, achievement of fertility, and changes in most body systems. Puberty)

Other related findings

• Situs inversus:
  • Present in about 50% of patients with PCD
  • Situs inversus presents as situs inversus totalis, which is a complete mirror-image reversal of the circulatory system and viscera, including the heart (dextrocardia).
  • Causes no apparent health problems and often remains undiagnosed until a chest radiograph is ordered
  • Can be part of Kartagener syndrome: a triad of situs inversus, chronic sinusitis Sinusitis Sinusitis refers to inflammation of the mucosal lining of the paranasal sinuses. The condition usually occurs concurrently with inflammation of the nasal mucosa (rhinitis), a condition known as rhinosinusitis. Acute sinusitis is due to an upper respiratory infection caused by a viral, bacterial, or fungal agent. Sinusitis, and bronchiectasis Bronchiectasis Bronchiectasis is a chronic disease of the airways that results from permanent bronchial distortion. This results from a continuous cycle of inflammation, bronchial damage and dilation, impaired clearance of secretions, and recurrent infections. Bronchiectasis
• Heterotaxy syndrome (situs ambiguus):
  • Defect in right-left laterality, which results in abnormalities in arrangements of the heart, liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver, intestines, or spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen
  • Organs may be structurally abnormal or abnormally positioned.
  • Patients may exhibit asplenia Asplenia Asplenia is the absence of splenic tissue or function and can stem from several factors ranging from congenital to iatrogenic. There is a distinction between anatomic asplenia, which is due to the surgical removal of the spleen, and functional asplenia, which is due to a condition that leads to splenic atrophy, infarct, congestion, or infiltrative disease. Asplenia or polysplenia.
• Transposition of the great arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries
• Hydrocephalus
• Fertility issues:
  • Infertility Infertility Infertility is the inability to conceive in the context of regular intercourse. The most common causes of infertility in women are related to ovulatory dysfunction or tubal obstruction, whereas, in men, abnormal sperm is a common cause. Infertility in men due to live, but immotile sperm
  • Impaired fertility in women due to impaired ciliary function in the fallopian tubes
• Epispadias 
• Pyloric stenosis

Diagnosis

Evaluation of ciliary function

There is no gold standard diagnostic test for PCD, but the following evaluations aid in the diagnosis: 

• Nasal nitric oxide (nNO) determination:
  • Measures NO levels
  • Low or absent in PCD
  • Screening tool (needs confirmation, as similar findings are noted in viral infection and cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis in rare instances)
• Assessment of ciliary motion and ultrastructure using high-speed video microscopy analysis (HSVA) and transmission electron microscopy:
  • Ciliated epithelium Epithelium The epithelium is a complex of specialized cellular organizations arranged into sheets and lining cavities and covering the surfaces of the body. The cells exhibit polarity, having an apical and a basal pole. Structures important for the epithelial integrity and function involve the basement membrane, the semipermeable sheet on which the cells rest, and interdigitations, as well as cellular junctions. Surface Epithelium obtained via nasal brushing using bronchoscopy (at least 4–6 weeks after a respiratory infection)
  • Ciliary beat frequency and pattern observed on video
  • Structural defects of cilia determined using electron microscopy
• Cell cultures of ciliated cells:
  • Epithelia obtained using a cytology brush
  • Cilia are regrown and their ability to rotate cells is observed.
  • PCD: cells do not rotate
• Genetic testing is useful in individuals exhibiting characteristic clinical features.
• Measures of mucociliary transport:
  • Low availability and low sensitivity
  • Rarely used

Additional tests

• Spirometry: reveals mild-to-moderate obstructive disease with variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables response to bronchodilators
• Chest X-ray and high-resolution CT (HRCT) used to evaluate worsening lung function can usually reveal:
  • Hyperinflation
  • Peribronchial thickening
  • Atelectasis Atelectasis Atelectasis is the partial or complete collapse of a part of the lung. Atelectasis is almost always a secondary phenomenon from conditions causing bronchial obstruction, external compression, surfactant deficiency, or scarring. Atelectasis
  • Bronchiectasis (present on HRCT in all adults and about 50% of children with PCD)
• Sinus CT scan is obtained in patients with chronic sinusitis Sinusitis Sinusitis refers to inflammation of the mucosal lining of the paranasal sinuses. The condition usually occurs concurrently with inflammation of the nasal mucosa (rhinitis), a condition known as rhinosinusitis. Acute sinusitis is due to an upper respiratory infection caused by a viral, bacterial, or fungal agent. Sinusitis who present with the following signs and symptoms:
  • Persistent mucociliary drainage
  • Nasal obstruction or blockage
  • Facial pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain or pressure

Management and Prognosis

Management

Treatment is individualized and guided by the clinical presentation of the patient.

• Main goals of management:
  • Control and treat all infections.
  • Remove trapped mucus from the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs and airways.
  • Treatment techniques are based on the experience of treating cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis and other forms of bronchiectasis Bronchiectasis Bronchiectasis is a chronic disease of the airways that results from permanent bronchial distortion. This results from a continuous cycle of inflammation, bronchial damage and dilation, impaired clearance of secretions, and recurrent infections. Bronchiectasis.
• Monitoring: 
  • Close and continuous follow-up 
  • Spirometry at every visit (average 1–3 times annually) starting at 6 years of age
• Management depends on the clinical course of the patient:
  • Bronchiectasis:
    • Daily chest physiotherapy
    • Use of selective antibiotics (guided by sputum cultures) to help clear secretions and decrease microbial load
    • For acute exacerbation of bronchiectasis Bronchiectasis Bronchiectasis is a chronic disease of the airways that results from permanent bronchial distortion. This results from a continuous cycle of inflammation, bronchial damage and dilation, impaired clearance of secretions, and recurrent infections. Bronchiectasis: oral antibiotics
    • For P. aeruginosa infections or severe pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia: IV antibiotics
    • Preventive antibiotic therapy for recurrent exacerbations in patients ≥ 7 years of age is usually using macrolides Macrolides Macrolides and ketolides are antibiotics that inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit and blocking transpeptidation. These antibiotics have a broad spectrum of antimicrobial activity but are best known for their coverage of atypical microorganisms. Macrolides and Ketolides
    • Vaccination Vaccination Vaccination is the administration of a substance to induce the immune system to develop protection against a disease. Unlike passive immunization, which involves the administration of pre-performed antibodies, active immunization constitutes the administration of a vaccine to stimulate the body to produce its own antibodies. Vaccination against influenza Influenza Influenza viruses are members of the Orthomyxoviridae family and the causative organisms of influenza, a highly contagious febrile respiratory disease. There are 3 primary influenza viruses (A, B, and C) and various subtypes, which are classified based on their virulent surface antigens, hemagglutinin (HA) and neuraminidase (NA). Influenza typically presents with a fever, myalgia, headache, and symptoms of an upper respiratory infection. Influenza Viruses/Influenza and pneumococcus
    • Smoking cessation
  • Chronic rhinosinusitis and nasal polyposis:
    • Nasal saline lavage
    • Intranasal glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids for nasal polyposis
    • Antibiotics for exacerbations
  • Chronic otitis media with effusion: 
    • Can lead to hearing loss Hearing loss Hearing loss, also known as hearing impairment, is any degree of impairment in the ability to apprehend sound as determined by audiometry to be below normal hearing thresholds. Clinical presentation may occur at birth or as a gradual loss of hearing with age, including a short-term or sudden loss at any point. Hearing Loss
    • Consider the use of a tympanostomy tube.
  • Male infertility: Consider in vitro fertilization Fertilization To undergo fertilization, the sperm enters the uterus, travels towards the ampulla of the fallopian tube, and encounters the oocyte. The zona pellucida (the outer layer of the oocyte) deteriorates along with the zygote, which travels towards the uterus and eventually forms a blastocyst, allowing for implantation to occur. Fertilization and First Week techniques.
• End-stage respiratory insufficiency:
  • Bilateral lung transplantation
  • In case of situs inversus: heart-lung transplantation

Prognosis

• Patients generally have a normal lifespan.
• Slower rate of reduction in lung function than cystic fibrosis Cystic fibrosis Cystic fibrosis is an autosomal recessive disorder caused by mutations in the gene CFTR. The mutations lead to dysfunction of chloride channels, which results in hyperviscous mucus and the accumulation of secretions. Common presentations include chronic respiratory infections, failure to thrive, and pancreatic insufficiency. Cystic Fibrosis
• Repeated and chronic infections may impact the ability to work full-time.

Differential Diagnosis

• Cystic fibrosis: an autosomal recessive Autosomal recessive Autosomal inheritance, both dominant and recessive, refers to the transmission of genes from the 22 autosomal chromosomes. Autosomal recessive diseases are only expressed when 2 copies of the recessive allele are inherited. Autosomal Recessive and Autosomal Dominant Inheritancedisorder caused by mutations in the CFTR gene leading to dysfunctional chloride channels. The defective chloride channels lead to hyperviscous mucus and the accumulation of secretions. Cystic fibrosis commonly presents with recurrent respiratory infections, pancreatic insufficiency, and failure to thrive Failure to Thrive Failure to thrive (FTT), or faltering growth, describes suboptimal weight gain and growth in children. The majority of cases are due to inadequate caloric intake; however, genetic, infectious, and oncological etiologies are also common. Failure to Thrive. Diagnosis is using a sweat chloride test followed by genetic testing. Cystic fibrosis has a worse prognosis than PCD. 
• IgG subclass deficiency: a decrease in 1 or more subclasses of IgG antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins with normal levels of other immunoglobulins Immunoglobulins Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins. Patients are often asymptomatic but may have recurrent infections of the ears, bronchi, sinuses, and lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs. Updated vaccinations and antibiotics are part of the management. Immunoglobulin therapy is an option if initial management is not successful in controlling infections.
• Granulomatosis with polyangiitis Granulomatosis with Polyangiitis Granulomatosis with polyangiitis (GPA) is a rare autoimmune disease of unknown etiology. It leads to a necrotizing granulomatous inflammation of small and medium-sized blood vessels of the nose, sinuses, throat, lungs, and kidneys. Granulomatosis with Polyangiitis: a type of vasculitis that results in damage to various organ systems, particularly the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys and respiratory tract. Granulomatosis with polyangiitis Granulomatosis with Polyangiitis Granulomatosis with polyangiitis (GPA) is a rare autoimmune disease of unknown etiology. It leads to a necrotizing granulomatous inflammation of small and medium-sized blood vessels of the nose, sinuses, throat, lungs, and kidneys. Granulomatosis with Polyangiitis can lead to constitutional symptoms, chronic upper respiratory infections, nosebleeds, ear pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis, and/or hematuria. Patients can progress to kidney failure. Granulomatosis with polyangiitis Granulomatosis with Polyangiitis Granulomatosis with polyangiitis (GPA) is a rare autoimmune disease of unknown etiology. It leads to a necrotizing granulomatous inflammation of small and medium-sized blood vessels of the nose, sinuses, throat, lungs, and kidneys. Granulomatosis with Polyangiitis demonstrates c-ANCA positivity and is treated with corticosteroids along with an immunosuppressant.