Impact of cilia ultrastructural examination on the diagnosis of primary ciliary dyskinesia

Respiratory Aspects of Primary Ciliary Dyskinesia

This review article explores the respiratory aspects of primary ciliary dyskinesia (PCD), a rare, heterogenous, genetic disorder characterized by impaired motile ciliary function. It discusses the clinical diagnosis and management strategies for PCD-related respiratory disease, including chronic sinusitis, otitis media with effusion, recurrent pneumonia, and bronchiectasis. The review emphasizes the need for a multidisciplinary approach to optimize care and clinical trials to improve outcomes in individuals with PCD, highlighting the importance of accurate diagnosis.

Recognizing clinical features of primary ciliary dyskinesia in the perinatal period

Primary ciliary dyskinesia (PCD) is a rare, motile ciliopathy inherited through mostly autosomal recessive variants that results in chronic ear, sinus, and respiratory disease. Despite neonatal respiratory distress being a common presenting symptom in term infants with PCD, the diagnosis is often delayed due to non-familiarity of neonatal caregivers with phenotypic and diagnostic features of this disease. Organ laterality defects, prenatal cerebral ventriculomegaly, and a family history of suppurative respiratory disease may occur in PCD and should prompt neonatal testing for this condition. In this review of neonatal PCD diagnoses in a large PCD clinic, prevalence and details of neonatal PCD issues are presented, highlighting the typically delayed onset of neonatal respiratory distress and lobar atelectasis on chest radiography, specific presentations in premature neonates, and responses to perinatal therapies.

Primary Ciliary Dyskinesia: A Clinical Review

Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous, motile ciliopathy, characterized by neonatal respiratory distress, recurrent upper and lower respiratory tract infections, subfertility, and laterality defects. Diagnosis relies on a combination of tests for confirmation, including nasal nitric oxide (nNO) measurements, high-speed videomicroscopy analysis (HSVMA), immunofluorescent staining, axonemal ultrastructure analysis via transmission electron microscopy (TEM), and genetic testing. Notably, there is no single gold standard confirmatory or exclusionary test. Currently, 54 causative genes involved in cilia assembly, structure, and function have been linked to PCD; this rare disease has a spectrum of clinical manifestations and emerging genotype-phenotype relationships. In this review, we provide an overview of the structure and function of motile cilia, the emerging genetics and pathophysiology of this rare disease, as well as clinical features associated with motile ciliopathies, novel diagnostic tools, and updates on genotype-phenotype relationships in PCD.

Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a rare, genetic disease characterized by dysfunctional motile cilia and abnormal mucociliary clearance, resulting in chronic sino-oto-pulmonary disease, neonatal respiratory distress, subfertility, and organ laterality defects. Over the past 2 decades, research and international collaborations have led to an improved understanding of disease prevalence, classic and variable phenotypes, novel diagnostics, genotype-phenotype correlations, long term morbidity, and innovative therapeutics. However, PCD is often underrecognized in clinical settings and the recent analyses of genetic databases suggest that only a fraction of these patients are being accurately diagnosed. Knowledge of significant advancements, from pathophysiology to the expanded range of clinical manifestations, will have important clinical impacts. These may include increasing disease recognition, improving diagnostic testing and management, and establishing an adequate pool of affected patients to enroll in upcoming clinical therapeutic trials. The objective of this state-of-the-art review is for readers to gain a greater understanding of the clinical spectrum of motile ciliopathies, cutting-edge diagnostic practices, emerging genotype-phenotype associations, and currently accepted management of people with PCD.

Clinical Characteristics and Immune Responses in Children with Primary Ciliary Dyskinesia during Pneumonia Episodes: A Case-Control Study

OBJECTIVE

This study explored the clinical features and immune responses of children with primary ciliary dyskinesia (PCD) during pneumonia episodes.

METHODS

The 61 children with PCD who were admitted to hospital because of pneumonia were retrospectively enrolled into this study between April 2017 and August 2022. A total of 61 children with pneumonia but without chronic diseases were enrolled as the control group. The clinical characteristics, levels of inflammatory indicators, pathogens, and imaging features of the lungs were compared between the two groups.

RESULTS

The PCD group had higher levels of lymphocytes (42.80% versus 36.00%, p = 0.029) and eosinophils (2.40% versus 1.25%, p = 0.020), but lower neutrophil counts (3.99 versus 5.75 × 109/L, p = 0.011), percentages of neutrophils (46.39% versus 54.24%, p = 0.014), CRP (0.40 versus 4.20 mg/L, p < 0.001) and fibrinogen (257.50 versus 338.00 mg/dL, p = 0.010) levels. Children with PCD and children without chronic diseases were both most commonly infected with Mycoplasma pneumoniae (24.6% versus 51.9%). Children with PCD had significantly more common imaging features, including mucous plugging (p = 0.042), emphysema (p = 0.007), bronchiectasis (p < 0.001), mosaic attenuation (p = 0.012), interstitial inflammation (p = 0.015), and sinusitis (p < 0.001).

CONCLUSION

PCD is linked to immune system impairment, which significantly contributes to our understanding of the pathophysiology of this entity.

Progress in Diagnosing Primary Ciliary Dyskinesia: The North American Perspective

Primary Ciliary Dyskinesia (PCD) is a rare, under-recognized disease that affects respiratory ciliary function, resulting in chronic oto-sino-pulmonary disease. The PCD clinical phenotype overlaps with other common respiratory conditions and no single diagnostic test detects all forms of PCD. In 2018, PCD experts collaborated with the American Thoracic Society (ATS) to create a clinical diagnostic guideline for patients across North America, specifically considering the local resources and limitations for PCD diagnosis in the United States and Canada. Nasal nitric oxide (nNO) testing is recommended for first-line testing in patients ≥5 years old with a compatible clinical phenotype; however, all low nNO values require confirmation with genetic testing or ciliary electron micrograph (EM) analysis. Furthermore, these guidelines recognize that not all North American patients have access to nNO testing and isolated genetic testing is appropriate in cases with strong clinical PCD phenotypes. For unresolved diagnostic cases, referral to a PCD Foundation accredited center is recommended. The purpose of this narrative review is to provide insight on the North American PCD diagnostic process, to enhance the understanding of and adherence to current guidelines, and to promote collaboration with diagnostic pathways used outside of North America.

Diagnosis of Primary Ciliary Dyskinesia. An Official American Thoracic Society Clinical Practice Guideline

BACKGROUND

This document presents the American Thoracic Society clinical practice guidelines for the diagnosis of primary ciliary dyskinesia (PCD).

TARGET AUDIENCE

Clinicians investigating adult and pediatric patients for possible PCD.

METHODS

Systematic reviews and, when appropriate, meta-analyses were conducted to summarize all available evidence pertinent to our clinical questions. Evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach for diagnosis and discussed by a multidisciplinary panel with expertise in PCD. Predetermined conflict-of-interest management strategies were applied, and recommendations were formulated, written, and graded exclusively by the nonconflicted panelists. Three conflicted individuals were also prohibited from writing, editing, or providing feedback on the relevant sections of the manuscript.

RESULTS

After considering diagnostic test accuracy, confidence in the estimates for each diagnostic test, relative importance of test results studied, desirable and undesirable direct consequences of each diagnostic test, downstream consequences of each diagnostic test result, patient values and preferences, costs, feasibility, acceptability, and implications for health equity, the panel made recommendations for or against the use of specific diagnostic tests as compared with using the current reference standard (transmission electron microscopy and/or genetic testing) for the diagnosis of PCD.

CONCLUSIONS

The panel formulated and provided a rationale for the direction as well as for the strength of each recommendation to establish the diagnosis of PCD.

Accuracy of Nasal Nitric Oxide Measurement as a Diagnostic Test for Primary Ciliary Dyskinesia. A Systematic Review and Meta-analysis

RATIONALE

Primary ciliary dyskinesia (PCD) is a rare disorder causing chronic otosinopulmonary disease, generally diagnosed through evaluation of respiratory ciliary ultrastructure and/or genetic testing. Nasal nitric oxide (nNO) measurement is used as a PCD screening test because patients with PCD have low nNO levels, but its value as a diagnostic test remains unknown.

OBJECTIVES

To perform a systematic review to assess the utility of nNO measurement (index test) as a diagnostic tool compared with the reference standard of electron microscopy (EM) evaluation of ciliary defects and/or detection of biallelic mutations in PCD genes.

DATA SOURCES

Ten databases were searched for reference sources from database inception through July 29, 2016.

DATA EXTRACTION

Study inclusion was limited to publications with rigorous nNO index testing, reference standard diagnostic testing with EM and/or genetics, and calculable diagnostic accuracy information for cooperative patients (generally >5 yr old) with high suspicion of PCD.

SYNTHESIS

Meta-analysis provided a summary estimate for sensitivity and specificity and a hierarchical summary receiver operating characteristic curve. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess study quality, and Grading of Recommendations Assessment, Development, and Evaluation was used to assess the certainty of evidence. In 12 study populations (1,344 patients comprising 514 with PCD and 830 without PCD), using a reference standard of EM alone or EM and/or genetic testing, summary sensitivity was 97.6% (92.7-99.2) and specificity was 96.0% (87.9-98.7), with a positive likelihood ratio of 24.3 (7.6-76.9), a negative likelihood ratio of 0.03 (0.01-0.08), and a diagnostic odds ratio of 956.8 (141.2-6481.5) for nNO measurements. After studies using EM alone as the reference standard were excluded, the seven studies using an extended reference standard of EM and/or genetic testing showed a summary sensitivity of nNO measurements of 96.3% (88.7-98.9) and specificity of 96.4% (85.1-99.2), with a positive likelihood ratio of 26.5 (5.9-119.1), a negative likelihood ratio of 0.04 (0.01-0.12), and a diagnostic odds ratio of 699.3 (67.4-7256.0). Certainty of the evidence was graded as moderate.

CONCLUSIONS

nNO is a sensitive and specific test for PCD in cooperative patients (generally >5 yr old) with high clinical suspicion for this disease. With a moderate level of evidence, this meta-analysis confirms that nNO testing using velum closure maneuvers has diagnostic accuracy similar to EM and/or genetic testing for PCD when cystic fibrosis is ruled out. Thus, low nNO values accompanied by an appropriate clinical phenotype could be used as a diagnostic PCD test, though EM and/or genetics will continue to provide confirmatory information.

Nasal versus tracheobronchial biopsies to diagnose primary ciliary dyskinesia: A meta-analysis

OBJECTIVES/HYPOTHESIS

To systematically review the literature regarding the efficacy of different biopsy sites and methods to obtain an adequate ciliary sample for ultrastructural examination with electron microscopy (EM) for the diagnosis of primary ciliary dyskinesia (PCD).

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A literature search was conducted with respect to the diagnosis of PCD. English studies with five or more subjects were included. Successful biopsy was defined as an adequate ciliary sample to make or exclude the diagnosis of PCD.

RESULTS

Eight studies met inclusion criteria. These studies included 1,993 patients who underwent 2,299 ciliary biopsies. Included studies were level 3 or 4 evidence. The weighted pooled proportion of obtaining an adequate specimen from a nasal biopsy was 76% (95% confidence interval [CI], 64%-86%) versus 66% (95% CI, 62%-69%) for a tracheobronchial site (P = 0.10). The pooled proportion of obtaining an adequate sample was 68% for both brush and forceps biopsy groups (95% CI, 58%-77% and 54%-81%, respectively). Nasal scraping yielded a higher proportion of adequate specimens (pooled proportion of 92%; 95% CI, 82%-99%) than other techniques (P = 0.002).

CONCLUSION

Tissue biopsy is one component of diagnosing PCD. We found no significant difference between biopsy sites in terms of obtaining an adequate ciliary sample for EM evaluation. This suggests that nasal biopsy should be preferred for patients old enough to tolerate an office biopsy without the need for general anesthesia. The merits of nasal versus tracheobronchial biopsy in the operating room depend more on the risks and benefits of the procedure being performed.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:6-13, 2017.

Primary ciliary dyskinesia in adults

INTRODUCTION

Primary ciliary dyskinesia is an autosomal recessive genetic disorder leading to structural and/or functional abnormalities of motor cilia. Impaired mucociliary clearance is responsible for the development of a multi-organ disease, which particularly affects the upper and lower airways.

STATE OF THE ART

In adults, primary ciliary dyskinesia is mainly characterized by bronchiectasis and chronic ear and sinus disorders. Situs inversus is found in half of patients and fertility disorders are commonly associated. Diagnosis is based on specialized tests: reduced level of nasal nitric oxide concentrations is suggestive of primary ciliary dyskinesia, but only a nasal or bronchial biopsy/brushing with analysis of beat pattern by videomicroscopy and/or analysis of cilia morphology by electronic microscopy can confirm the diagnosis. However, the diagnosis is difficult to achieve due to the limited access to these specialized tests and to difficulties in interpreting them. Genetic tests are under development and may provide new diagnostic tools. Treatment is symptomatic, based on airway clearance techniques (e.g., physiotherapy) and systemic and/or inhaled antibiotics. Prognosis is related to the severity of the respiratory impairment, which can be moderate or severe.

PERSPECTIVES AND CONCLUSIONS

Diagnosis and management of primary ciliary dyskinesia remain poorly defined and should be supported by specialized centers to standardize the diagnosis, improve the treatment and promote research.