Primary ciliary dyskinesia, an orphan disease

Primary ciliary dyskinesia: overlooked and undertreated in children

Primary ciliary dyskinesia (PCD) is a multi-organ disorder associated with chronic oto-sino-pulmonary disease, neonatal respiratory distress, situs abnormalities and reduced fertility. Repeated respiratory tract infections leads to the almost universal development of bronchiectasis. These clinical manifestations are a consequence of poorly functioning motile cilia. However, confirming the diagnosis is quite difficult and is often delayed, so the true incidence of PCD may be significantly higher than current estimates. Nasal nitric oxide has been earmarked as a useful screening tool for identifying patients, but its use is limited in pre-school-aged children. Due to the rarity of PCD, the evidence base for management is somewhat limited, and treatment regimens are extrapolated from other suppurative lung disorders, like cystic fibrosis.

Systematic discovery of novel ciliary genes through functional genomics in the zebrafish

Cilia are microtubule-based hair-like organelles that play many important roles in development and physiology, and are implicated in a rapidly expanding spectrum of human diseases, collectively termed ciliopathies. Primary ciliary dyskinesia (PCD), one of the most prevalent of ciliopathies, arises from abnormalities in the differentiation or motility of the motile cilia. Despite their biomedical importance, a methodical functional screen for ciliary genes has not been carried out in any vertebrate at the organismal level. We sought to systematically discover novel motile cilia genes by identifying the genes induced by Foxj1, a winged-helix transcription factor that has an evolutionarily conserved role as the master regulator of motile cilia biogenesis. Unexpectedly, we find that the majority of the Foxj1-induced genes have not been associated with cilia before. To characterize these novel putative ciliary genes, we subjected 50 randomly selected candidates to a systematic functional phenotypic screen in zebrafish embryos. Remarkably, we find that over 60% are required for ciliary differentiation or function, whereas 30% of the proteins encoded by these genes localize to motile cilia. We also show that these genes regulate the proper differentiation and beating of motile cilia. This collection of Foxj1-induced genes will be invaluable for furthering our understanding of ciliary biology, and in the identification of new mutations underlying ciliary disorders in humans.

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.

Comparison of conventional pulmonary rehabilitation and high-frequency chest wall oscillation in primary ciliary dyskinesia

BACKGROUND

Enhancement of mucociliary clearance by pulmonary rehabilitation (PR) is advocated in primary ciliary dyskinesia (PCD). Our primary aim was to compare the efficacy and safety of postural drainage, percussion and vibration [conventional PR (CPR)], and high frequency chest wall oscillation (HFCWO) by studying change in pulmonary function. Our secondary aim was to evaluate patient preferences regarding the two methods.

METHODS

This was a controlled randomized crossover study. PCD patients between the ages of 7 and 18 years were assigned to two groups, first group performed airway clearance with CPR at hospital for 5 days and after a 2-day washout period HFCWO was applied to the same group at home. HFCWO was applied first to the other group and then these patients were hospitalized for CPR. The primary outcome measure of the study was pulmonary function test (PFT). The secondary outcomes were pulse arterial oxygen saturation (SpO2 ) and the perceived efficiency and comfort level.

RESULTS

PFT values of patients increased significantly after both PR methods (before/after): CPR: FVC: 77.0 ± 14.1/81.8 ± 13.0 (P = 0.002); FEV1 : 72.9 ± 14.8/78.7 ± 13.5 (P = 0.001); PEF: 73.8 ± 14.5/82.5 ± 14.5 (P = 0.001); FEF25-75 : 68.6 ± 27.6/74.9 ± 29.3 (P = 0.007).

HFCWO FVC

75.1 ± 15.3/80.3 ± 13.9 (P = 0.002); FEV1 : 71.4 ± 16/77.4 ± 14.6 (P = 0.001); PEF: 70.9 ± 18.0/78.3 ± 17.7 (P = 0.002); FEF25-75 : 70.5 ± 23.4/76.4 ± 25.6 (P = 0.006). There were no significant differences in % predicted FVC, FEV1 , PEF, and FEF25-75 increased values with CPR and HFCWO. HFCWO was found more comfortable (P = 0.04). Two PR methods were found efficient and no desaturation occurred during PR.

CONCLUSIONS

PFTs were significantly increased after both PR methods. There were no differences in PFTs and SpO2 between the CPR and HFCWO groups. Both PR methods were found efficient. HFCWO was found more comfortable. HFCWO may be an option in patients with chronic pulmonary disease and low adherence to PR.

Diagnostic accuracy of nitric oxide measurements to detect primary ciliary dyskinesia

BACKGROUND

Primary Ciliary Dyskinesia (PCD) is an orphan disease characterized by recurrent respiratory infections and an increased prevalence of situs inversus and male infertility. Low nasal Nitric Oxide (nNO) is used as a new test to diagnose PCD. The test sensitivity is good, but specificity has not been studied widely. Therefore, we evaluated the diagnostic accuracy of low nNO to diagnose PCD in a large cohort, including healthy patients and different disease controls.

MATERIALS AND METHODS

Nasal nitric oxide was measured during plateau exhalation against resistance (nNOplat) and during tidal breathing (nNOtid). Moreover, we measured fractional exhaled NO (FENO). We included 226 patients: 38 with PCD, 49 healthy controls, and 139 disease controls (cystic fibrosis, humoral immunodeficiency, and asthma).

RESULTS

The nNOplat cut-off value of 300 ppb provided the best sensitivity (89·5%) and specificity (87·3%) to detect PCD. There was overlap between PCD and disease controls: 16·5% of disease controls had a false-positive result. nNOtid correlated with nNOplat (r=0·912), but values differed (P=0·0001). The nNOtid cut-off of 200 ppb had a sensitivity of 89·5% and a specificity of 80·6% to detect PCD. The FENO cut-off of 10 ppb had an acceptable sensitivity (89·5%), but a low specificity (58·3%). Positive and negative likelihood ratios were suboptimal for all tests.

CONCLUSIONS

nNOplat, nNOtid and FENO measurements overlap between PCD and disease controls. Sensitivity is comparable for the three tests. Applying composite scores slightly improves diagnostic accuracy. Given the less than 90% test sensitivity, PCD should be considered in patients with intermediate results.

Primary ciliary dyskinesia and humoral immunodeficiency--is there a missing link?

BACKGROUND

Primary ciliary dyskinesia (PCD) and humoral mmunodeficiency (HID) are both rare disorders which cause recurrent upper and lower respiratory tract infections.

OBJECTIVE

To examine the concurrence of PCD and HID in a patient cohort with known PCD.

METHODS

Retrospective review of the patient files.

RESULTS

We describe 11 patients of a cohort of 168 patients with PCD (6.5%) with a combination of PCD and some form of HID. The patients all presented with typical clinical symptoms for PCD, however the role of the concomitant immunological abnormalities is not clear.

CONCLUSION

PCD and HID coincided in 6.5% of the patients. We suggest that a common pathophysiological pathway results in both disorders.

Switching on cilia: transcriptional networks regulating ciliogenesis

Cilia play many essential roles in fluid transport and cellular locomotion, and as sensory hubs for a variety of signal transduction pathways. Despite having a conserved basic morphology, cilia vary extensively in their shapes and sizes, ultrastructural details, numbers per cell, motility patterns and sensory capabilities. Emerging evidence indicates that this diversity, which is intimately linked to the different functions that cilia perform, is in large part programmed at the transcriptional level. Here, we review our understanding of the transcriptional control of ciliary biogenesis, highlighting the activities of FOXJ1 and the RFX family of transcriptional regulators. In addition, we examine how a number of signaling pathways, and lineage and cell fate determinants can induce and modulate ciliogenic programs to bring about the differentiation of distinct cilia types.

Primary ciliary dyskinesia complicated with diffuse panbronchiolitis: a case report and literature review

Background

Fifty percent of patients with primary ciliary dyskinesia (PCD) have situs inversus. Diffuse panbronchiolitis (DPB) might be one of the characteristic features of the lung in PCD.

Methods

We reported a case of PCD without situs inversus, yet complicated with DPB, and did literature review.

Results

A 34-year-old nonsmoking Chinese woman with 6-year primary infertility suffered from recurrent episodes of respiratory tract infections since childhood. Lung auscultation revealed end-inspiratory coarse crackles. Pulmonary function tests demonstrated mild obstructive ventilation functional impairment. Lung biopsy showed respiratory bronchiolitis. Nasal mucosa cilia showed the absence of both outer and inner dynein arms of the microtubules. Saccharin test was positive. Chest images showed bronchiectasis and bronchiolitis but no situs inversus. Paranasal sinus computed tomography (CT) showed maxillary sinusitis and ethmoid sinusitis. A culture of bronchoalveolar lavage fluid was positive for Pseudomonas aeruginosa. Her conditions improved in clinical symptoms and CT images after 2 months of treatment with azithromycin. Literature review revealed that very rare patients were diagnosed as PCD complicated with diffuse DPB, and all of them had situs inversus.

Conclusions

The association of DPB might be one of the characteristic features of the lung in PCD. Further studies on the concurrence of these two diseases are suggested so as to elucidate the mechanism of both.

Please cite this paper as: Chen W, Shao C, Song Y and Bai C. Primary ciliary dyskinesia complicated with diffuse panbronchiolitis: a case report and literature review. Clin Respir J 2014; 8: 425–430.

Primary cilia in neurodevelopmental disorders

Primary cilia are generally solitary organelles that emanate from the surface of almost all vertebrate cell types. Until recently, details regarding the function of these structures were lacking; however, extensive evidence now suggests that primary cilia have critical roles in sensing the extracellular environment, and in coordinating developmental and homeostatic signalling pathways. Furthermore, disruption of these functions seems to underlie a diverse spectrum of disorders, known as primary ciliopathies. These disorders are characterized by wide-ranging clinical and genetic heterogeneity, but with substantial overlap among distinct conditions. Indeed, ciliopathies are associated with a large variety of manifestations that often include distinctive neurological findings. Herein, we review neurological features associated with primary ciliopathies, highlight genotype-phenotype correlations, and discuss potential mechanisms underlying these findings.

Reduced nasal nitric oxide production in cystic fibrosis patients with elevated systemic inflammation markers

Background

Nitric oxide (NO) is produced within the respiratory tract and can be detected in exhaled bronchial and nasal air. The concentration varies in specific diseases, being elevated in patients with asthma and bronchiectasis, but decreased in primary ciliary dyskinesia. In cystic fibrosis (CF), conflicting data exist on NO levels, which are reported unexplained as either decreased or normal. Functionally, NO production in the paranasal sinuses is considered as a location-specific first-line defence mechanism. The aim of this study was to investigate the correlation between upper and lower airway NO levels and blood inflammatory parameters, CF-pathogen colonisation, and clinical data.

Methods and Findings

Nasal and bronchial NO concentrations from 57 CF patients were determined using an electrochemical analyser and correlated to pathogen colonisation of the upper and lower airways which were microbiologically assessed from nasal lavage and sputum samples. Statistical analyses were performed with respect to clinical parameters (lung function, BMI), laboratory findings (CRP, leucocytes, total-IgG, fibrinogen), and anti-inflammatory and antibiotic therapy. There were significant correlations between nasal and bronchial NO levels (rho = 0.48, p<0.001), but no correlation between NO levels and specific pathogen colonisation. In patients receiving azithromycin, significantly reduced bronchial NO and a tendency to reduced nasal NO could be found. Interestingly, a significant inverse correlation of nasal NO to CRP (rho = −0.28, p = 0.04) and to leucocytes (rho = −0.41, p = 0.003) was observed. In contrast, bronchial NO levels showed no correlation to clinical or inflammatory parameters.

Conclusion

Given that NO in the paranasal sinuses is part of the first-line defence mechanism against pathogens, our finding of reduced nasal NO in CF patients with elevated systemic inflammatory markers indicates impaired upper airway defence. This may facilitate further pathogen acquisition in the sinonasal area, with consequences for lung colonisation and the overall outcome in CF.

A complex of BBS1 and NPHP7 is required for cilia motility in zebrafish

Bardet-Biedl syndrome (BBS) and nephronophthisis (NPH) are hereditary autosomal recessive disorders, encoded by two families of diverse genes. BBS and NPH display several overlapping phenotypes including cystic kidney disease, retinitis pigmentosa, liver fibrosis, situs inversus and cerebellar defects. Since most of the BBS and NPH proteins localize to cilia and/or their appendages, BBS and NPH are considered ciliopathies. In this study, we characterized the function of the transcription factor Nphp7 in zebrafish, and addressed the molecular connection between BBS and NPH. The knockdown of zebrafish bbs1 and nphp7.2 caused similar phenotypic changes including convergent extension defects, curvature of the body axis, hydrocephalus, abnormal heart looping and cystic pronephros, all consistent with an altered ciliary function. Immunoprecipitation assays revealed a physical interaction between BBS1 and NPHP7, and the simultaneous knockdown of zbbs1 and znphp7.2 enhanced the cystic pronephros phenotype synergistically, suggesting a genetic interaction between zbbs1 and znphp7.2 in vivo. Deletion of zBbs1 or zNphp7.2 did not compromise cilia formation, but disrupted cilia motility. Although NPHP7 has been shown to act as transcriptional repressor, our studies suggest a crosstalk between BBS1 and NPHP7 in regulating normal function of the cilium.

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.

Endoscopic sinus surgery for treatment of kartagener syndrome: a case report

BACKGROUND

KARTAGENER SYNDROME (KS) IS A RARE CONGENITAL DISEASE CHARACTERISED BY A CLINICAL TRIAD OF SYMPTOMS: situs inversus, chronic rhinosinusitis, and bronchiectasis. Although congenital ciliary defect is recognised as the main cause of this syndrome, it remains difficult to treat the associated airway infection.

CASE REPORT

A 17-year-old female patient presented with repeated refractory airway infection. She also had bronchiectasis and situs inversus. Electron microscopic evaluation of her nasal mucosa revealed ciliary defect and confirmed the diagnosis of KS. She underwent functional endoscopic sinus surgery (FESS) followed by long-term postoperative debridement of the sinonasal cavity. This treatment reduced chronic rhinosinusitis and protected against subsequent airway infection in a 7-year follow-up.

CONCLUSION

FESS is effective for relieving both chronic rhinosinusitis and lung infection of KS in the long term.