Diagnostic testing of patients suspected of primary ciliary dyskinesia

Recent advances in primary ciliary dyskinesia genetics

Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder caused by the abnormal structure and/or function of motile cilia. The PCD diagnosis is challenging and requires a well-described clinical phenotype combined with the identification of abnormalities in ciliary ultrastructure and/or beating pattern as well as the recognition of genetic cause of the disease. Regarding the pace of identification of PCD-related genes, a rapid acceleration during the last 2–3 years is notable. This is the result of new technologies, such as whole-exome sequencing, that have been recently applied in genetic research. To date, PCD-causative mutations in 29 genes are known and the number of causative genes is bound to rise. Even though the genetic causes of approximately one-third of PCD cases still remain to be found, the current knowledge can already be used to create new, accurate genetic tests for PCD that can accelerate the correct diagnosis and reduce the proportion of unexplained cases. This review aims to present the latest data on the relations between ciliary structure aberrations and their genetic basis.

Respiratory syncytial virus increases the virulence of Streptococcus pneumoniae by binding to penicillin binding protein 1a. A new paradigm in respiratory infection

RATIONALE

Respiratory syncytial virus (RSV) and Streptococcus pneumoniae are major respiratory pathogens. Coinfection with RSV and S. pneumoniae is associated with severe and often fatal pneumonia but the molecular basis for this remains unclear.

OBJECTIVES

To determine if interaction between RSV and pneumococci enhances pneumococcal virulence.

METHODS

We used confocal microscopy and Western blot to identify the receptors involved in direct binding of RSV and pneumococci, the effects of which were studied in both in vivo and in vitro models of infection. Human ciliated respiratory epithelial cell cultures were infected with RSV for 72 hours and then challenged with pneumococci. Pneumococci were collected after 2 hours exposure and changes in gene expression determined using quantitative real-time polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

Following incubation with RSV or purified G protein, pneumococci demonstrated a significant increase in the inflammatory response and bacterial adherence to human ciliated epithelial cultures and markedly increased virulence in a pneumonia model in mice. This was associated with extensive changes in the pneumococcal transcriptome and significant up-regulation in the expression of key pneumococcal virulence genes, including the gene for the pneumococcal toxin, pneumolysin. We show that mechanistically this is caused by RSV G glycoprotein binding penicillin binding protein 1a.

CONCLUSIONS

The direct interaction between a respiratory virus protein and the pneumococcus resulting in increased bacterial virulence and worsening disease outcome is a new paradigm in respiratory infection.

Diagnosis and management of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited autosomal-recessive disorder of motile cilia characterised by chronic lung disease, rhinosinusitis, hearing impairment and subfertility. Nasal symptoms and respiratory distress usually start soon after birth, and by adulthood bronchiectasis is invariable. Organ laterality defects, usually situs inversus, occur in ∼50% of cases. The estimated prevalence of PCD is up to ∼1 per 10,000 births, but it is more common in populations where consanguinity is common. This review examines who to refer for diagnostic testing. It describes the limitations surrounding diagnosis using currently available techniques and considers whether recent advances to genotype patients with PCD will lead to genetic testing and screening to aid diagnosis in the near future. It discusses the challenges of monitoring and treating respiratory and ENT disease in children with PCD.

Primary Ciliary Dyskinesia: An Update on New Diagnostic Modalities and Review of the Literature

Primary ciliary dyskinesia (PCD) is a genetic condition affecting approximately 1 in 15,000-20,000 individuals, and the majority of cases exhibit an autosomal recessive inheritance pattern. However, genetic heterogenicity is seen in PCD and reflects the complexity of ciliary structure and biogenesis. There have been many recent advances in the diagnosis and management of PCD in the last few years, including advanced genetic sequencing, nasal nitric oxide assay, and ciliary motility tests. This article focuses on the ultrastructure and pathophysiology of ciliary dyskinesias, along with a review of clinical features, screening, and diagnostic tests. It also reflects upon the diagnostic challenge caused by the diverse clinical presentation, which will be of great value to pediatricians for considering PCD in their differential list, henceforth leading to early recognition and management, along with awareness of the recent advances in the field of genetics and other techniques for diagnosis of this condition.

Genetic Testing in the Diagnosis of Primary Ciliary Dyskinesia: State-of-the-Art and Future Perspectives

Primary ciliary dyskinesia (PCD) is a heterogeneous autosomal recessive condition affecting around 1:15,000. In people with PCD, microscopic motile cilia do not move normally resulting in impaired clearance of mucus and debris leading to repeated sinopulmonary infection. If diagnosis is delayed, permanent bronchiectasis and deterioration of lung function occurs. Other complications associated with PCD include congenital heart disease, hearing impairment and infertility. A small number of longitudinal studies suggest that lung function deteriorates before diagnosis of PCD but may stabilise following diagnosis with subsequent specialist management. Early diagnosis is therefore essential, but for a number of reasons referral for diagnostic testing is often delayed until older childhood or even adulthood. Functional diagnostic tests for PCD are expensive, time consuming and require specialist equipment and scientists. In the last few years, there have been considerable developments to identify genes associated with PCD, currently enabling 65% of patients to be identified by bi-allelic mutations. The rapid identification of new genes continues. This review will consider the evidence that early diagnosis of PCD is beneficial. It will review the recent advances in identification of PCD-associated genes and will discuss the role of genetic testing in PCD. It will then consider whether screening for PCD antenatally or in the new born is likely to become a feasible and acceptable for this rare disease.

Culture of primary ciliary dyskinesia epithelial cells at air-liquid interface can alter ciliary phenotype but remains a robust and informative diagnostic aid

Background

The diagnosis of primary ciliary dyskinesia (PCD) requires the analysis of ciliary function and ultrastructure. Diagnosis can be complicated by secondary effects on cilia such as damage during sampling, local inflammation or recent infection. To differentiate primary from secondary abnormalities, re-analysis of cilia following culture and re-differentiation of epithelial cells at an air-liquid interface (ALI) aids the diagnosis of PCD. However changes in ciliary beat pattern of cilia following epithelial cell culture has previously been described, which has brought the robustness of this method into question. This is the first systematic study to evaluate ALI culture as an aid to diagnosis of PCD in the light of these concerns.

Methods

We retrospectively studied changes associated with ALI-culture in 158 subjects referred for diagnostic testing at two PCD centres. Ciliated nasal epithelium (PCD n = 54; non-PCD n = 111) was analysed by high-speed digital video microscopy and transmission electron microscopy before and after culture.

Results

Ciliary function was abnormal before and after culture in all subjects with PCD; 21 PCD subjects had a combination of static and uncoordinated twitching cilia, which became completely static following culture, a further 9 demonstrated a decreased ciliary beat frequency after culture. In subjects without PCD, secondary ciliary dyskinesia was reduced.

Conclusions

The change to ciliary phenotype in PCD samples following cell culture does not affect the diagnosis, and in certain cases can assist the ability to identify PCD cilia.

Coexistence of two rare genetic disorders: Kartagener syndrome and familial Mediterranean fever

Primary ciliary dyskinesia (PCD) is a rare disease, predominantly inherited as an autosomal recessive, with ciliary dysfunction leading to impaired mucociliary clearance, chronic airway infection and inflammation. Situs inversus totalis occurs in ~50 % of PCD patients and it is known as Kartagener syndome. Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of fever and peritonitis, pleuritis, arthritis, or erysipelas-like skin disease. FMF is caused by mutations in the MEFV gene which is located on chromosome 16p13.3. p.M680I, p.M694 V, p.M694I, p.V726A on exon 10 and p.E148Q on exon 2 are the most common mutations among FMF patients and these constitute 85 % of all. Homozygosity of R202Q polymorphism is strongly associated with FMF. We would like to present a case of Kartagener syndrome accompanied by FMF with R202Q polymorphism. Our case is the first in the literature indicating the accidental coexistence of FMF and Kartagener syndrome.

Ciliated cultures from patients with primary ciliary dyskinesia do not produce nitric oxide or inducible nitric oxide synthase during early infection

BACKGROUND

The mechanism behind why patients with primary ciliary dyskinesia (PCD) exhibit low nasal and exhaled nitric oxide (NO) remains unknown. One hypothesis is that reduced NO biosynthesis is caused by a defect in one or more NO synthases (NOSs). In healthy cells, the biosynthesis of NO is increased following exposure to respiratory pathogens. Here, we aimed to investigate whether ciliated epithelial cells from patients with PCD increase NO production following pneumococcal infection.

METHODS

Human respiratory epithelium was cultured to a basal or ciliated cell phenotype using submerged or air-liquid interface cultures, respectively. Cells were exposed to media or pneumococci until cells became damaged (< 4 h). Apical fluids were collected prior and following infection, and NO production was determined using chemiluminescence. NOS gene expression was determined using real-time quantitative polymerase chain reaction.

RESULTS

Levels of NO and NOS2 gene expression increased significantly following infection of healthy ciliated epithelial cells but not basal cells. No increase in NO was seen in ciliated cell cultures from patients with PCD, and NOS2 gene expression remained unchanged from baseline.

CONCLUSIONS

These results suggest that the biosynthesis of NO in ciliated cells from patients with PCD is abnormal following early bacterial challenge, suggesting an abnormality in the function of inducible NOS in PCD.

Primary ciliary dyskinesia. Recent advances in diagnostics, genetics, and characterization of clinical disease

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia that leads to oto-sino-pulmonary diseases and organ laterality defects in approximately 50% of cases. The estimated incidence of PCD is approximately 1 per 15,000 births, but the prevalence of PCD is difficult to determine, primarily because of limitations in diagnostic methods that focus on testing ciliary ultrastructure and function. Diagnostic capabilities have recently benefitted from (1) documentation of low nasal nitric oxide production in PCD and (2) discovery of biallelic mutations in multiple PCD-causing genes. The use of these complementary diagnostic approaches shows that at least 30% of patients with PCD have normal ciliary ultrastructure. More accurate identification of patients with PCD has also allowed definition of a strong clinical phenotype, which includes neonatal respiratory distress in >80% of cases, daily nasal congestion and wet cough starting soon after birth, and early development of recurrent/chronic middle-ear and sinus disease. Recent studies, using advanced imaging and pulmonary physiologic assessments, clearly demonstrate early onset of lung disease in PCD, with abnormal air flow mechanics by age 6-8 years that is similar to cystic fibrosis, and age-dependent onset of bronchiectasis. The treatment of PCD is not standardized, and there are no validated PCD-specific therapies. Most patients with PCD receive suboptimal management, which should include airway clearance, regular surveillance of pulmonary function and respiratory microbiology, and use of antibiotics targeted to pathogens. The PCD Foundation is developing a network of clinical centers, which should improve diagnosis and management of PCD.

Primary ciliary dyskinesia. Recent advances in diagnostics, genetics, and characterization of clinical disease

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia that leads to oto-sino-pulmonary diseases and organ laterality defects in approximately 50% of cases. The estimated incidence of PCD is approximately 1 per 15,000 births, but the prevalence of PCD is difficult to determine, primarily because of limitations in diagnostic methods that focus on testing ciliary ultrastructure and function. Diagnostic capabilities have recently benefitted from (1) documentation of low nasal nitric oxide production in PCD and (2) discovery of biallelic mutations in multiple PCD-causing genes. The use of these complementary diagnostic approaches shows that at least 30% of patients with PCD have normal ciliary ultrastructure. More accurate identification of patients with PCD has also allowed definition of a strong clinical phenotype, which includes neonatal respiratory distress in >80% of cases, daily nasal congestion and wet cough starting soon after birth, and early development of recurrent/chronic middle-ear and sinus disease. Recent studies, using advanced imaging and pulmonary physiologic assessments, clearly demonstrate early onset of lung disease in PCD, with abnormal air flow mechanics by age 6-8 years that is similar to cystic fibrosis, and age-dependent onset of bronchiectasis. The treatment of PCD is not standardized, and there are no validated PCD-specific therapies. Most patients with PCD receive suboptimal management, which should include airway clearance, regular surveillance of pulmonary function and respiratory microbiology, and use of antibiotics targeted to pathogens. The PCD Foundation is developing a network of clinical centers, which should improve diagnosis and management of PCD.

Primary ciliary dyskinesia presentation in 60 children according to ciliary ultrastructure

Primary ciliary dyskinesia (PCD) is an inherited disease related to ciliary dysfunction, with heterogeneity in clinical presentation and in ciliary ultrastructural defect. Our study intended to determine if there are phenotypic differences in patients with PCD based on ciliary ultrastructural abnormality. In this retrospective study carried out among 60 children with a definitive diagnosis of PCD, we analyzed clinical, radiological, and functional features at diagnosis and at last recorded visit, according to cilia defect (absence of dynein arms: DAD group, n = 36; abnormalities of the central complex: CCA group, n = 24). Onset of respiratory symptoms occurred later in the CCA than in the DAD group (9.5 versus 0.5 months, p = 0.03). Situs inversus was only observed in the DAD group, while respiratory disease in siblings were more frequent in the CCA group (p = 0.003). At diagnosis, clinical presentation was more severe in the CCA group: frequency of respiratory tract infections (p = 0.008), rhinosinusitis (p = 0.02), otitis complications (p = 0.0001), bilateral bronchiectasis (p = 0.04), and number of hypoxemic patients (p = 0.03). Pulmonary function remained stable in both groups, but outcome was better in the CCA than in the DAD group: less antibiotic therapy and hypoxemic patients (p = 0.004). In conclusion, our results underlined the relationship between the severity of clinical presentation and the ultrastructural ciliary defect.

[Congenital ciliary dyskinesia. Focus]

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disease, caused by specific primary structural and/or functional abnormalities of the motile cilia. Prevalence, about 1/15,000 to 1/30,000, is probably underestimated, as diagnosis might not be evocated in absence of Kartagener syndrome. Diagnosis is confirmed in presence of abnormal ciliary motility as well as ciliary ultrastructure. Disease-causing mutations in at least 16 genes have already been identified; analysis will be guided by the type of ultrastructural abnormalities. An early and adequate diagnosis and therapy can theoretically improve the prognosis of the disease.

Ciliary ultrastructure in patients with chronic rhinosinusitis and primary ciliary dyskinesia

The Cilia represent one of the main mechanisms contributing to the clearance of microorganisms and particles from the respiratory epithelium. Primary ciliary dyskinesia (PCD) is a genetically determined disorder characterized by irreversible systemic dysmotility of the cilia. Secondary ciliary dyskinesia (SCD) differs from primary defects on the reversible ultrastructural alterations that can occur after any insult to a previously normal mucosa. Hence, this study aimed to describe and compare the main ultrastructural ciliary features in PCD and SCD through transmission electron microscopy. The most frequent PCD abnormalities were missing or short dynein arms, missing central microtubules, and displacement of one of the nine peripheral doublets. The most common changes found in SCD were compound cilia and peripheral microtubule alterations associated with modifications of the respiratory epithelium. PCD presented a higher percentage of altered cilia (>30 %) when compared to SCD (5 %), demonstrating that SCD is more limited in area than PCD. Whereas in PCD the changes in the dynein arms and in the central microtubules are fundamental for diagnostic confirmation, the diagnosis of SCD usually involves compound cilia and disarrangements in peripheral microtubules.

Quantitative analysis of ciliary beating in primary ciliary dyskinesia: a pilot study

Background

Primary ciliary dyskinesia (PCD) is a rare congenital respiratory disorder characterized by abnormal ciliary motility leading to chronic airway infections. Qualitative evaluation of ciliary beat pattern based on digital high-speed videomicroscopy analysis has been proposed in the diagnosis process of PCD. Although this evaluation is easy in typical cases, it becomes difficult when ciliary beating is partially maintained. We postulated that a quantitative analysis of beat pattern would improve PCD diagnosis. We compared quantitative parameters with the qualitative evaluation of ciliary beat pattern in patients in whom the diagnosis of PCD was confirmed or excluded.

Methods

Nasal nitric oxide measurement, nasal brushings and biopsies were performed prospectively in 34 patients with suspected PCD. In combination with qualitative analysis, 12 quantitative parameters of ciliary beat pattern were determined on high-speed videomicroscopy recordings of beating ciliated edges. The combination of ciliary ultrastructural abnormalities on transmission electron microscopy analysis with low nasal nitric oxide levels was the “gold standard” used to establish the diagnosis of PCD.

Results

This “gold standard” excluded PCD in 15 patients (non-PCD patients), confirmed PCD in 10 patients (PCD patients) and was inconclusive in 9 patients. Among the 12 parameters, the distance traveled by the cilium tip weighted by the percentage of beating ciliated edges presented 96% sensitivity and 95% specificity. Qualitative evaluation and quantitative analysis were concordant in non-PCD patients. In 9/10 PCD patients, quantitative analysis was concordant with the “gold standard”, while the qualitative evaluation was discordant with the “gold standard” in 3/10 cases. Among the patients with an inconclusive “gold standard”, the use of quantitative parameters supported PCD diagnosis in 4/9 patients (confirmed by the identification of disease-causing mutations in one patient) and PCD exclusion in 2/9 patients.

Conclusions

When the beat pattern is normal or virtually immotile, the qualitative evaluation is adequate to study ciliary beating in patients suspected for PCD. However, when cilia are still beating but with moderate alterations (more than 40% of patients suspected for PCD), quantitative analysis is required to precise the diagnosis and can be proposed to select patients eligible for TEM.

Effectiveness of sequencing selected exons of DNAH5 and DNAI1 in diagnosis of primary ciliary dyskinesia

INTRODUCTION

Primary ciliary dyskinesia (PCD) is a rare genetically heterogenous condition. Mutations in DNAH5 or DNAI1 genes can be found in about a third of the patients with PCD. Increased occurrence of mutations was described in several exons of these long genes. The objective of the study was to test the sensitivity of sequencing of selected 13 exons (as compared to costly sequencing of all 100 exons of the two genes), and to determine the prevalence of the DNAH5 or DNAI1 mutations in the Czech PCD database.

METHODS

The Czech national PCD database has identified 31 pediatric patients, diagnosed based on clinical findings and tests on the ciliated epithelium. Twenty-seven patients from 24 families agreed on genetic testing. In the first step, direct sequencing of selected 13 exons (9 of DNAH5 and 4 of DNAI1) was performed, and then we compared its effectiveness in detecting at least one mutation with results of sequencing all 100 exons of the two genes.

RESULTS

The sequencing of all exons identified compound heterozygosity for PCD mutations in nine patients from eight families (DNAH5 in eight and DNAI1 in one patient), and heterozygozity for a DNAH5 mutation of uncertain functional significance in one additional patient. The first step of selected exon sequencing detected a mutation in five out of these eight families, its actual sensitivity being 62.5%, with a high predictive value. The phenotypic and clinical characteristics of all the paediatric patients with PCD are shown.

CONCLUSIONS

Selected exon sequencing detects at least one mutated allele in over a half of our patients who have PCD due to DNAH5 or DNAI1 mutations. To lower the costs of the genetic testing, targeted step-wise genetic testing may be a reasonable approach to detect mutations in PCD patients, especially if their phenotype is taken into account.

ciliaFA: a research tool for automated, high-throughput measurement of ciliary beat frequency using freely available software

Background

Analysis of ciliary function for assessment of patients suspected of primary ciliary dyskinesia (PCD) and for research studies of respiratory and ependymal cilia requires assessment of both ciliary beat pattern and beat frequency. While direct measurement of beat frequency from high-speed video recordings is the most accurate and reproducible technique it is extremely time consuming. The aim of this study was to develop a freely available automated method of ciliary beat frequency analysis from digital video (AVI) files that runs on open-source software (ImageJ) coupled to Microsoft Excel, and to validate this by comparison to the direct measuring high-speed video recordings of respiratory and ependymal cilia. These models allowed comparison to cilia beating between 3 and 52 Hz.

Methods

Digital video files of motile ciliated ependymal (frequency range 34 to 52 Hz) and respiratory epithelial cells (frequency 3 to 18 Hz) were captured using a high-speed digital video recorder. To cover the range above between 18 and 37 Hz the frequency of ependymal cilia were slowed by the addition of the pneumococcal toxin pneumolysin. Measurements made directly by timing a given number of individual ciliary beat cycles were compared with those obtained using the automated ciliaFA system.

Results

The overall mean difference (± SD) between the ciliaFA and direct measurement high-speed digital imaging methods was −0.05 ± 1.25 Hz, the correlation coefficient was shown to be 0.991 and the Bland-Altman limits of agreement were from −1.99 to 1.49 Hz for respiratory and from −2.55 to 3.25 Hz for ependymal cilia.

Conclusions

A plugin for ImageJ was developed that extracts pixel intensities and performs fast Fourier transformation (FFT) using Microsoft Excel. The ciliaFA software allowed automated, high throughput measurement of respiratory and ependymal ciliary beat frequency (range 3 to 52 Hz) and avoids operator error due to selection bias. We have included free access to the ciliaFA plugin and installation instructions in Additional file 1 accompanying this manuscript that other researchers may use.

Mutations in radial spoke head genes and ultrastructural cilia defects in East-European cohort of primary ciliary dyskinesia patients

Primary ciliary dyskinesia (PCD) is a rare (1/20,000), multisystem disease with a complex phenotype caused by the impaired motility of cilia/flagella, usually related to ultrastructural defects of these organelles. Mutations in genes encoding radial spoke head (RSPH) proteins, elements of the ciliary ultrastructure, have been recently described. However, the relative involvement of RSPH genes in PCD pathogenesis remained unknown, due to a small number of PCD families examined for mutations in these genes. The purpose of this study was to estimate the involvement of RSPH4A and RSPH9 in PCD pathogenesis among East Europeans (West Slavs), and to shed more light on ultrastructural ciliary defects caused by mutations in these genes. The coding sequences of RSPH4A and RSPH9 were screened in PCD patients from 184 families, using single strand conformational polymorphism analysis and sequencing. Two previously described (Q109X; R490X) and two new RSPH4A mutations (W356X; IVS3_2–5del), in/around exons 1 and 3, were identified; no mutations were found in RSPH9. We estimate that mutations in RSPH4A, but not in RSPH9, are responsible for 2–3% of cases in the East European PCD population (4% in PCD families without situs inversus; 11% in families preselected for microtubular defects). Analysis of the SNP-haplotype background provided insight into the ancestry of repetitively found mutations (Q109X; R490X; IVS3_2–5del), but further studies involving other PCD cohorts are required to elucidate whether these mutations are specific for Slavic people or spread among other European populations. Ultrastructural defects associated with the mutations were analyzed in the transmission electron microscope images; almost half of the ciliary cross-sections examined in patients with RSPH4A mutations had the microtubule transposition phenotype (9+0 and 8+1 pattern). While microtubule transposition was a prevalent ultrastructural defect in cilia from patients with RSPH4A mutations, similar defects were also observed in PCD patients with mutations in other genes.

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.

Primary Ciliary Dyskinesia in Children: A Review for Pediatricians, Allergists, and Pediatric Pulmonologists

Primary ciliary dyskinesia (PCD) is a rare genetic condition that causes impaired mucociliary clearance due to poorly functioning cilia. PCD is one disease manifestation of the many recently recognized associations with ciliary malfunction, referred to as "ciliopathies." Manifestations of PCD commonly begin in the neonatal period with cough, pneumonia, and chronic ear infections or effusions. Approximately half of the affected individuals have situs inversus totalis. The diagnosis is often made in later childhood or early adulthood, because symptoms mimic more common childhood illnesses and because the definitive diagnosis of PCD can be challenging. Treatment recommendations are largely based on therapies used for other conditions with impaired mucociliary clearance in the absence of evidence-based research specific for PCD. Early recognition and initiation of both otolaryngologic and pulmonary management might reduce potential long-term morbidities. The purpose of this article is to update primary care providers, allergists, and pediatric pulmonologists on recent advances in this interesting condition.

Ultrastructural pathology of primary ciliary dyskinesia: report about 125 cases in Germany

Background

Primary ciliary dyskinesia (PCD) is a rare genetically induced disorder of cilia inducing mainly respiratory diseases. Transmission electron microscopy (TEM) analysis of ciliary ultrastructure is classically used for diagnosis. We report our experience of TEM investigations in a large series of patients.

Methods

TEM analysis performed of 742 biopsies from patients with suspected PCD was reviewed retrospectively. Ultrastructural defects were analysized further in 125 cases with changes typical for PCD.

Results

In 18.1% of patients diagnosis of PCD was made because of morphological alterations, in 68.2% secondary changes were seen. In 13.7% material was not feasible for analysis. Mostly defects of dynein arms were detected in PCD (96.8%). In particular defects of the inner arms (51.2%) and combined dynein defects (37.6%) were found. Total loss of dynein arms was dominant. Only in 3.2% deficiencies of central structures were found alone. Associated situs inversus or dextracardia was reported clinically in 21.4%.

Conclusions

TEM analysis is possible in most patients and a useful tool for diagnosis of PCD. Functional and genetic analysis should be done additionally. Registers should be installed to collect all available informations and push further research.

[Are investigations for underlying causes needed for the management of an adult patient with bronchiectasis?]

Bronchiectasis may result from various causes. Recognition of these underlying causes may lead to specific management. Focal bronchiectasis are related to luminal blockage or extrinsic narrowing. The causative factors of diffuse bronchiectasis may be suggested by the predominant distribution of the disease and associated extrapulmonary manifestations. Primary immunodeficiencies cystic fibrosis, allergic bronchopulmonary aspergillosis, chronic Mycobacterium avium complex infection, and systemic diseases have to be looked for, even in patients with knowledge of a childhood respiratory infection.

Primary ciliary dyskinesia: evaluation using cilia beat frequency assessment via spectral analysis of digital microscopy images

Ciliary beat frequency (CBF) measurements provide valuable information for diagnosing of primary ciliary dyskinesia (PCD). We developed a system for measuring CBF, used it in association with electron microscopy to diagnose PCD, and then analyzed characteristics of PCD patients. The CBF measurement system was based on power spectra measured through digital imaging. Twenty-four patients suspected of having PCD (age 1-19 yr) were selected from a group of 75 children and adolescents with pneumopathies of unknown causes. Ten healthy, nonsmoking volunteers (age ≥ 17 yr) served as a control group. Nasal brush samples were collected, and CBF and electron microscopy were performed. PCD was diagnosed in 12 patients: 5 had radial spoke defects, 3 showed absent central microtubule pairs with transposition, 2 had outer dynein arm defects, 1 had a shortened outer dynein arm, and 1 had a normal ultrastructure. Previous studies have reported that the most common cilia defects are in the dynein arm. As expected, the mean CBF was higher in the control group (P < 0.001) and patients with normal ultrastructure (P < 0.002), than in those diagnosed with cilia ultrastructural defects (i.e., PCD patients). An obstructive ventilatory pattern was observed in 70% of the PCD patients who underwent pulmonary function tests. All PCD patients presented bronchial wall thickening on chest computed tomography scans. The protocol and diagnostic techniques employed allowed us to diagnose PCD in 16% of patients in this study.

Diagnostic yield of nasal scrape biopsies in primary ciliary dyskinesia: a multicenter experience

Examination of ciliary ultrastructure remains the cornerstone diagnostic test for primary ciliary dyskinesia (PCD), a disease of abnormal ciliary structure and/or function. Obtaining a biopsy with sufficient interpretable cilia and producing quality transmission electron micrographs (TEM) is challenging. Methods for processing tissues for optimal preservation of axonemal structures are not standardized. This study describes our experience using a standard operating procedure (SOP) for collecting nasal scrape biopsies and processing TEMs in a centralized laboratory. We enrolled patients with suspected PCD at research sites of the Genetic Disorders of Mucociliary Clearance Consortium. Biopsies were performed according to a SOP whereby curettes were used to scrape the inferior surface of the inferior turbinate, with samples placed in fixative. Specimens were shipped to a central laboratory where TEMs were prepared and blindly reviewed. Four hundred forty-eight specimens were obtained from 107 young children (0-5 years), 189 older children (5-18 years), and 152 adults (> 18 years), and 88% were adequate for formal interpretation. The proportion of adequate specimens was higher in adults than in children. Fifty percent of the adequate TEMs showed normal ciliary ultrastructure, 39% showed hallmark ultrastructural changes of PCD, and 11% had indeterminate findings. Among specimens without clearly normal ultrastructure, 72% had defects of the outer and/or inner dynein arms (IDA), while 7% had central apparatus defects with or without IDA defects. In summary, nasal scrape biopsies can be performed in the outpatient setting and yield interpretable samples, when performed by individuals with adequate training and experience according to an SOP.

Kartagener syndrome

Kartagener syndrome is a rare, ciliopathic, autosomal recessive genetic disorder that causes a defect in the action of the cilia lining the respiratory tract and fallopian tube. Patients usually present with chronic recurrent rhinosinusitis, otitis media, pneumonia, and bronchiectasis caused by pseudomonal infection. Situs inversus can be seen in about 50% of cases. Diagnosis can be made by tests to prove impaired cilia function, biopsy, and genetic studies. Treatment is supportive. In severe cases, the prognosis can be fatal if bilateral lung transplantation is delayed. We present a case of a 66-year-old woman with chronic recurrent upper respiratory infections, pseudomonal pneumonia, and chronic bronchiectasis who presented with acute respiratory failure. She was diagnosed with Kartagener syndrome based on her clinical presentation and genetic studies. She expired on ventilator with refractory respiratory and multiorgan failure.

Cooling of cilia allows functional analysis of the beat pattern for diagnostic testing

BACKGROUND

Reports of the effect of low temperatures on ciliary beat frequency (CBF) are conflicting, and the effect on ciliary beat pattern has not been reported. We aimed to clarify this association and determine whether cooling of cilia may allow ciliary function to be assessed without the need of expensive high-speed video microscopy.

METHODS

Fourteen nasal brush biopsy samples were collected, and the CBF and beat pattern of undisrupted ciliated edges were evaluated. Two methods were used to strictly control changes in temperature: One enabled rapid transitory measurements during cooling and warming, and the other was used to maintain accurate low temperatures over longer periods of time.

RESULTS

A sigmoid relationship between CBF and temperature was observed. CBF decreased with cooling and increased with warming. Ciliary function was unaffected by the direction of temperature change and was maintained down to 2°C. The percentage of dyskinetic cilia observed at 2°C or 4°C was unchanged from that at 37°C.

CONCLUSIONS

Contrary to previous research, our data show that cilia continue to beat with a normal pattern at temperatures as low as 2°C. Slowing of cilia by cooling may allow detailed analysis of ciliary beat pattern without the need of expensive high-speed video microscopy.