Primäre ziliäre Dyskinesie

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder with defective structure or function of normally motile cilia, leading to chronic upper and lower respiratory tract infections, fertility problems and organ site abnormalities. The PCD is a genetically heterogeneous condition entailing a broad range of different disease variants. Diagnosing these different PCD phenotypes requires a combined approach using complementary methods for detection of defects of ciliary function, ultrastructure and composition as well as low nasal nitric oxide values and biallelic genetic mutations. To date, mutations in 31 different genes have been linked to PCD permitting a genetic diagnosis in approximately 60?% of cases. Due to the lack of adequate trials evidence-based knowledge on the epidemiology, disease course and management of PCD is currently lacking. An international PCD registry has been developed to overcome these limitations (www.pcdregistry.eu) and is currently recruiting patients. Current treatment regimens have to rely on expert opinions and on experience gained from other respiratory diseases. The management of PCD includes surveillance of pulmonary function, culturing upper and lower airway secretions and diagnostic imaging. Daily airway clearance techniques as well as prompt antibiotic treatment of infections are the cornerstones of PCD treatment regimens.     

Dyskinésie ciliaire primitive

Primary ciliary dyskinesia (PCD, MIM 242650) is an inherited respiratory disease caused by functional and ultrastructural abnormalities of respiratory cilia. This disorder, which affects 1 in 16,000 individuals, is usually transmitted as an autosomal recessive trait. In half the cases, PCD is associated with situs inversus (Kartagener syndrome). PCD is characterized by impaired mucociliary clearance resulting from a lack of ciliary motion, which is responsible for recurrent respiratory infections. The most frequent and first identified ciliary defect involves the dynein arms. The genetic heterogeneity underlying PCD is extremely important, and only three genes have as yet been identified in a few PCD patients with absence of outer dynein arms. The main clinical symptoms, at pulmonary and ENT levels, the abnormalities of ciliary structure and function, and the molecular basis of PCD will be reported in this review.     

The challenges of diagnosing primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic disorder of ciliary structure and function. The diagnosis can be challenging, particularly when using nongenetic assays. The "gold standard" diagnostic test is ultrastructural analysis of respiratory cilia obtained by nasal scrape or brush biopsy. A few specialized centers use high-speed videomicroscopy to examine ciliary beat. Certain beat patterns correlate with ultrastructural defects, and, in some cases, subtle alterations in beat pattern can be seen when ultrastructure is normal. Recent studies have shown that nasal nitric oxide (NO) is very low in patients with PCD compared with healthy control subjects; therefore, this assay may be a useful screening or adjunctive test for PCD. Because acute respiratory illnesses may yield alterations in ciliary ultrastructure, ciliary beat, and nasal NO values, these tests should be performed during a stable baseline period. Identification of an array of PCD genes has provided the opportunity for making a definitive genetic diagnosis for PCD in some cases. All of these approaches have a role in diagnosing PCD. For example, PCD has been confirmed by identifying disease-causing mutations in a heavy dynein chain gene in individuals with normal ciliary ultrastructure but subtle defects in ciliary beat and low nasal NO. Priorities to improve nongenetic diagnostic capability include standardization of nasal NO as a screening test and the development of specialized centers using uniform approaches for the analysis of ciliary ultrastructure and ciliary beat pattern. Another chapter in this issue (see Zariwala and colleagues, pp. 430) addresses the progress toward improved capabilities for definitive genetic testing.     

Update of respiratory tract disease in children with primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic disease characterized by abnormal ciliary structure and function leading to impaired mucociliary clearance and chronic progressive sinopulmonary disease. Upper and lower respiratory tract manifestations are cardinal features of PCD. This review summarizes the current state of knowledge of respiratory tract disease in individuals with PCD and highlights the challenges in identifying and quantifying lung disease in very young children with PCD. No specific therapies are available to correct ciliary dysfunction in PCD. Treatment is not evidence based, and recommendations are largely extrapolated from cystic fibrosis and other conditions with impaired mucociliary clearance. There is a pressing need to develop and validate outcome measures, including patient-reported outcomes, that could be used to evaluate potential therapies in PCD. This review concludes with recommendations for clinical endpoints and outcome measures and a prioritized list of treatments to study in PCD clinical trials.     

Primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited disorder characterized by impaired ciliary function that leads to an array of clinical manifestations including chronic bronchitis, chronic sinusitis, chronic otitis media, situs inversus (in approximately 50% of cases), and infertility. The underlying genetic and molecular defects have not been defined. Molecular genetic studies have demonstrated multiple gene loci. In a few families, defects in genes encoding ciliary dynein proteins have been identified. PCD is an interesting disease to compare with cystic fibrosis (CF) because both are airway diseases associated with impaired mucociliary clearance and with chronic infection of the airways leading to bronchiectasis as well as chronic infection of the sinuses that may be associated with nasal polyposis. The progression of the lower airway disease appears less rapid in PCD. Unlike CF, PCD is commonly associated with chronic otitis media, respiratory problems during the neonatal period, and situs inversus, suggesting that ciliary function is also important for clearing fluid/bacteria from the middle ear, for clearing fluid from the fetal lung during the transition to an air-filled neonatal lung, and for directing laterality of organs during embryonic development. The management for PCD lung disease is similar to that for CF and other diseases with chronic bronchitis leading to bronchiectasis.     

Primary ciliary dyskinesia: diagnostic and phenotypic features

Primary ciliary dyskinesia (PCD) is a genetic disease characterized by abnormalities in ciliary structure/function. We hypothesized that the major clinical and biologic phenotypic markers of the disease could be evaluated by studying a cohort of subjects suspected of having PCD. Of 110 subjects evaluated, PCD was diagnosed in 78 subjects using a combination of compatible clinical features coupled with tests of ciliary ultrastructure and function. Chronic rhinitis/sinusitis (n = 78; 100%), recurrent otitis media (n = 74; 95%), neonatal respiratory symptoms (n = 57; 73%), and situs inversus (n = 43; 55%) are strong phenotypic markers of the disease. Mucoid Pseudomonas aeruginosa (n = 12; 15%) and nontuberculous mycobacteria (n = 8; 10%) were present in older (> 30 years) patients with PCD. All subjects had defects in ciliary structure, 66% in the outer dynein arm. Nasal nitric oxide production was very low in PCD (nl/minute; 19 +/- 17 vs. 376 +/- 124 in normal control subjects). Rigorous clinical and ciliary phenotyping and measures of nasal nitric oxide are useful for the diagnosis of PCD. An increased awareness of the clinical presentation and diagnostic criteria for PCD will help lead to better diagnosis and care for this orphan disease.     

Mislocalization of DNAH5 and DNAH9 in respiratory cells from patients with primary ciliary dyskinesia

RATIONALE: Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder characterized by recurrent infections of the airways and situs inversus in half of the affected offspring. The most frequent genetic defects comprise recessive mutations of DNAH5 and DNAI1, which encode outer dynein arm (ODA) components. Diagnosis of PCD usually relies on electron microscopy, which is technically demanding and sometimes difficult to interpret. METHODS: Using specific antibodies, we determined the subcellular localization of the ODA heavy chains DNAH5 and DNAH9 in human respiratory epithelial and sperm cells of patients with PCD and control subjects by high-resolution immunofluorescence imaging. We also assessed cilia and sperm tail function by high-speed video microscopy. RESULTS: In normal ciliated airway epithelium, DNAH5 and DNAH9 show a specific regional distribution along the ciliary axoneme, indicating the existence of at least two distinct ODA types. DNAH5 was completely or only distally absent from the respiratory ciliary axoneme in patients with PCD with DNAH5- (n = 3) or DNAI1- (n = 1) mutations, respectively, and instead accumulated at the microtubule-organizing centers. In contrast to respiratory cilia, sperm tails from a patient with DNAH5 mutations had normal ODA heavy chain distribution, suggesting different modes of ODA generation in these cell types. Blinded investigation of a large cohort of patients with PCD and control subjects identified DNAH5 mislocalization in all patients diagnosed with ODA defects by electron microscopy (n = 16). Cilia with complete axonemal DNAH5 deficiency were immotile, whereas cilia with distal DNAH5 deficiency showed residual motility. CONCLUSIONS: Immunofluorescence staining can detect ODA defects, which will possibly aid PCD diagnosis.     

Primary ciliary dyskinesia with CCDC39 variants displaying specific ciliary ultrastructure and movement concordant with the genotype: A case report

Primary ciliary dyskinesia (PCD) is a genetic disease with chronic airway infection and inflammation caused by ciliary ultrastructural defects and impairment in ciliary function.We present an adult case of PCD with compound heterozygous nonsense variants in CCDC39. The ciliary ultrastructure findings using electron microscopy and ciliary movement using high-speed video analysis matched the genotype. This is the first case report of PCD with CCDC39 variants in Japan demonstrating specific ciliary ultrastructure and movement related to the genotype.     

The emerging genetics of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive, rare, genetically heterogeneous condition characterized by oto-sino-pulmonary disease together with situs abnormalities (Kartagener syndrome) owing to abnormal ciliary structure and function. Most patients are currently diagnosed with PCD based on the presence of defective ciliary ultrastructure. However, diagnosis often remains challenging due to variability in the clinical phenotype and ciliary ultrastructural changes. Some patients with PCD have normal ciliary ultrastructure, which further confounds the diagnosis. A genetic test for PCD exists but is of limited value because it investigates only a limited number of mutations in only two genes. The genetics of PCD is complicated owing to the complexity of axonemal structure that is highly conserved through evolution, which is comprised of multiple proteins. Identifying a PCD-causing gene is challenging due to locus and allelic heterogeneity. Despite genetic heterogeneity, multiple tools have been used, and there are 11 known PCD-causing genes. All of these genes combined explain approximately 50% of PCD cases; hence, more genes need to be identified. This review briefly describes the current knowledge regarding the genetics of PCD and focuses on the methodologies used to identify novel PCD-causing genes, including a candidate gene approach using model organisms, next-generation massively parallel sequencing techniques, and the use of genetically isolated populations. In conclusion, we demonstrate the multipronged approach that is necessary to circumvent challenges due to genetic heterogeneity to uncover genetic causes of PCD.     

Primary ciliary dyskinesia. A new phenotypic variant

Primary ciliary dyskinesia (PCD) is a genetic disorder characterized by the inability of ciliated structures to beat effectively. Clinical course includes recurrent sinus and ear infections, chronic or recurrent bronchitis and infertility in men. Although several phenotypes have been described, lung function deterioration secondary to bronchiectasis becomes severe only rarely. That upper airway tract infections go unnoticed has not been reported. We report a case of PCD characterized by immotile sperm, severe obstructive respiratory disorder that required a sequential double lung transplant with the absence of recurrent sinus and ear infections.     

Primäre ziliare Dyskinesie

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease characterized by abnormal ciliary motion and impaired mucociliary clearance. The prevalence of PCD is approximately 1:20,000 live births. Since cilia are common in many organs of the body, there is a wide variety of clinical manifestations in patients with PCD. Due to an extensive genetic heterogeneity the course of the disease varies largely, but with increasing age, the clinical symptoms are dominated by repeated respiratory infections and ultimately respiratory insufficiency. In the presence of situs inversus, which is observed in 50% of affected individuals, the diagnosis is easy, In cases of doubt, analyses of the kinetics and infrastructure of the cilia are necessary. The treatment of PCD is symptomatic. With optimal medical and physiotherapeutic management, the prognosis quoad vitam is good and life expectancy is nearly normal.     

Nasal ciliary ultrastructure and function in patients with primary ciliary dyskinesia compared with that in normal subjects and in subjects with various respiratory diseases

In an attempt to establish the relevance of ciliary ultrastructure to the pathophysiologic aspects of respiratory tract disease, we compared quantitatively the ultrastructure and function of cilia from healthy subjects (atopic and nonatopic nonsmokers, asymptomatic smokers) and patients with a variety of respiratory diseases (cystic fibrosis, chronic rhinitis, bronchiectasis associated with hypogammaglobulinemia, chronic bronchitis) with cilia from patients with primary ciliary dyskinesia (PCD). In healthy subjects and patients with non-PCD respiratory disease, approximately 5% of the cilia evaluated had ultrastructural abnormalities. Ciliary beat frequency was significantly higher in the chronic rhinitis group (15.3 +/- 1.2 Hz) than in the other non-PCD groups, which were within the normal range (12.5 +/- 1.7 Hz), and in all non-PCD cases ciliary wave form was normal. In each of these groups, normal mucociliary transport had been previously demonstrated. By contrast, in patients with PCD, the proportion of cilia with ultrastructural abnormalities was significantly greater than in the normal subjects and those with non-PCD respiratory disease (p less than 0.0001). In addition, beat frequency was significantly reduced, ciliary wave form was grossly abnormal, and pulmonary and nasal mucociliary transport were virtually absent. These findings demonstrate the relevance of ciliary ultrastructural abnormalities to altered ciliary function and lend support to the primary role of the demonstrated abnormalities in the respiratory tract disease of PCD.     

Ultrastructural ciliary defects in children with recurrent infections of the lower respiratory tract

One hundred fifty-four children with recurrent or chronic infections of the lower respiratory tract compatible with the diagnosis of primary ciliary dyskinesia (PCD) were evaluated for the presence of ultrastructural ciliary abnormalities. Studies were performed on multiple samples of respiratory mucosa obtained by nasal and bronchial brushing. Twenty-eight children showed ultrastructural ciliary defects compatible with the diagnosis of PCD: Twenty-four presented dynein arm deficiency (either as isolated defect or in association with microtubular abnormalities), two had ciliary aplasia, and two showed microtubular abnormalities. Eleven patients with PCD had situs viscerum inversus, bronchiectasis, and chronic sinusitis (Kartagener's syndrome); one child with Kartagener's syndrome had normal ciliary structure. The appearance of respiratory symptoms within the first month of life, the colonization by Haemophilus influenzae, and a history of recurrent rhinitis and otitis were characteristically present in children with PCD. The clinical status of those patients who reached adolescence was, in our experience, remarkably good. An early diagnosis with adequate prevention and therapy of respiratory infections may have an important role in minimizing irreversible lung damage.     

Diagnostik der primären ziliären Dyskinesie

Primary ciliary dyskinesia (PCD) is a phenotypically and genetically heterogeneous genetic disorder. The respiratory disease phenotype which is characterized by upper and lower airway infections results from inborn defects of respiratory cilia responsible for defective mucociliary clearance. Randomization of left/right body asymmetry is responsible for situs inversus (Kartagener’s syndrome) in half of affected individuals. As a screening test nasal nitric oxide measurement can be used. Establishment of the diagnosis currently relies on electron microscopy, high-resolution immunofluorescence analysis, and/or direct evaluation of ciliary beat by light microscopy. Recently mutations in the four genes DNAI1, DNAH5, TXNDC3, and DNAH11 that all encode for outer dynein arm proteins have been linked to recessive PCD. For diagnostic testing especially DNAH5 and DNAI1 mutation screening is useful, because they are responsible for more than 50% of PCD cases with outer dynein arm defects. Rarely mutations in RPGR (PCD + retinitis pigmentosa) and OFD1 (PCD + complex mental retardation syndrome) have been identified in X-linked recessive PCD variants.     

Primary ciliary dyskinesia and upper airway diseases

Primary ciliary dyskinesia (PCD) is a rare and difficultto-diagnose disease with morbidity related to infections of the upper and lower respiratory tract. The disease is caused by mutations in genes that are required for proper ciliary function. The defect in ciliary function results in reduced or absent mucociliary clearance, thereby predisposing the affected individual to repeated bacterial infections. Recent advances in the understanding of the basic biology and function of the cilium have led to the identification of some of the genes that are mutated in cases of PCD. Further studies of this disease will likely lead to earlier diagnosis, better treatment, and improved outcomes.     

Primary ciliary dyskinesia (PCD)

This article summarizes the current state of the scientific and clinical knowledge that relates to primary ciliary dyskinesia (PCD). Although PCD is a rare disease with a prevalence of 1 in 20,000 it has a well recognized morbidity. It is believed that an accurate diagnosis and the application of appropriate management can significantly reduce this morbidity. The cilia themselves are highly complicated organelles that perform important functions, particularly in the respiratory and reproductive tracts, and they have been the focus of many years of research. Our current knowledge of ciliary function and mucociliary clearance is summarized, and the relationship with laterality defects is discussed. A phenotype resembling PCD is also seen in animal models, and some of these are described before reviewing the clinical aspects of PCD in humans and new developments in the field that may have implications for the future investigation and management of affected individuals.     

Genetic causes of bronchiectasis: primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder reflecting abnormalities in the structure and function of motile cilia and flagella, causing impairment of mucociliary clearance, left-right body asymmetry, and sperm motility. Clinical manifestations include respiratory distress in term neonates, recurrent otosinopulmonary infections, bronchiectasis, situs inversus and/or heterotaxy, and male infertility. Genetic discoveries are emerging from family-based linkage studies and from testing candidate genes. Mutations in 2 genes, DNAI1 and DNAH5, frequently cause PCD as an autosomal recessive disorder. A clinical genetic test has been recently established for DNAI1 and DNAH5, which involves sequencing 9 exons that harbor the most common mutations. This approach will identify at least one mutation in these 2 genes in approximately 25% of PCD patients. If biallelic mutations are identified, the test is diagnostic. If only one mutation is identified, the full gene may be sequenced to search for a trans-allelic mutation. As more disease-causing gene mutations are identified, broader genetic screening panels will further identify patients with PCD. Ongoing investigations are beginning to identify genetic mutations in novel clinical phenotypes for PCD, such as congenital heart disease and male infertility, and new associations are being established between 'ciliary' genetic mutations and clinical phenotypes.     

Diagnostik der primären ziliären Dyskinesie

Characteristics

Primary ciliary dyskinesia (PCD) is a rare congenital disease of the cilia which is mostly manifested in the respiratory system.

Diagnostics

When there is a clinical suspicion of the presence of PCD and/or a positive screening result with reduced nasal nitrogen oxide (NO) values, further diagnostic measures should be initiated as soon as possible. As first diagnostic measure for confirmation or exclusion of PCD, high-speed videomicroscopy analysis (HVMA) should be carried out. If the findings are suggestive of PCD transmission electron microscopy (TEM) of the ciliary structure and high-resolution immunofluorescence (IF) microscopic analysis of the cilia should follow. Mandatory for the diagnosis are at least two congruent pathological findings from HVMA, TEM or IF. When a PCD variant with no evidence of ultrastructural defects is present, an identical pathological beating of cilia must be demonstrated with HVMA on three independent occasions. Following that, a targeted genetic clarification should be attempted based on the findings for HVMA, TEM and IF. A clear genetic result can also confirm the diagnosis.

Approach

When PCD is suspected contact with a diagnostic center should be initiated. A reference center for PCD diagnostics will evaluate uncertain findings.     

Gene Mutations in Primary Ciliary Dyskinesia Related to Otitis Media

Otitis media with effusion (OME) is the most common cause of conductive hearing loss in children and is strongly associated with primary ciliary dyskinesia (PCD). Approximately half of the children with PCD require otolaryngology care, posing a major problem in this population. Early diagnosis of PCD is critical in these patients to minimise the collateral damage related to OME. The current gold standard for PCD diagnosis requires determining ciliary structure defects by transmission electron microscopy (TEM) or clearly documenting ciliary dysfunction via digital high-speed video microscopy (DHSV). Although both techniques are useful for PCD diagnosis, they have limitations and need to be supported by new methodologies, including genetic analysis of genes related to PCD. In this article, we review classical and recently associated mutations related to ciliary alterations leading to PCD, which can be useful for early diagnosis of the disease and subsequent early management of OME.