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

Primary Ciliary Dyskinesia: The Impact of Taste Receptor (TAS2R38) Gene Polymorphisms on Disease Outcome and Severity

BACKGROUND

Primary ciliary dyskinesia (PCD) is a rare genetic disease leading to recurrent respiratory infections of upper and lower airways. Chronic rhinosinusitis (CRS) and bronchiectasis are very common in PCD patients. Recently, it has been shown the presence of taste receptors in respiratory tract and the possible involvement of bitter taste receptor TAS2R38 gene in susceptibility to respiratory infections and rhinosinusitis.

OBJECTIVE

Aim of this study was to evaluate the frequency of TAS2R38 polymorphisms in PCD patients and their possible correlations with clinical outcomes of the disease.

METHODS

Genetic and phenotypic data of 35 PCD patients were collected. Clinical evaluation included neonatal respiratory distress (NRD) at birth, presence of situs inversus, CRS, and bronchiectasis. We also measured the number of respiratory infections per year and the relevant pathogens, Lund-Mackay score, FEV1, and modified Bhalla score. With regard to genetics data, 3 polymorphisms (rs1726866, rs713598, and rs10246939) within TAS2R38 gene were analyzed and the patients were classified as PAV/PAV, PAV/AVI, and AVI/AVI.

RESULTS

A significant difference in the distribution of TAS2R38 haplotype between patients with and without NRD emerged (p value = 0.01). A lower percentage of PAV/PAV individuals showed frequent respiratory exacerbations (≥2/year) (p value = 0.04) compared to those with AVI/AVI and AVI/PAV haplotypes. Moreover, no patients homozygous for PAV/PAV haplotype presented chronic colonization by Pseudomonas aeruginosa, thus supporting the possible role of TAS2R38 gene in susceptibility to respiratory infections.

CONCLUSIONS

Here, we report, for the first time, a possible association of TAS2R38 polymorphisms with PCD phenotype.

Recognizing genetic disease: A key aspect of pediatric pulmonary care

Advancement in technology has improved recognition of genetic etiologies of disease, which has impacted diagnosis and management of rare disease patients in the pediatric pulmonary clinic. This review provides an overview of genetic conditions that are likely to present with pulmonary features and require extensive care by the pediatric pulmonologist. Increased familiarity with these conditions allows for improved care of these patients by reducing time to diagnosis, tailoring management, and prompting further investigation into these disorders.

Generation of two human induced pluripotent stem cell lines (MHHi017-A, MHHi017-B) from a patient with primary ciliary dyskinesia carrying a homozygous mutation (c.7915C > T [p.Arg2639*]) in the DNAH5 gene

Dynein axonemal heavy chain 5 (DNAH5) is part of a microtubule-associated protein complex found within the cilia of the lung. Mutations in the DNAH5 gene lead to impaired ciliary function and are linked to primary ciliary dyskinesia (PCD), a rare autosomal recessive disorder. We established two human induced pluripotent stem cell (hiPSC) lines generated from a patient with PCD and homozygous mutation in the corresponding DNAH5 gene. These cell lines represent an excellent tool for modeling the ciliary dysfunction in PCD.

Role of cilia in the pathogenesis of congenital heart disease

An essential role for cilia in the pathogenesis of congenital heart disease (CHD) has emerged from findings of a large-scale mouse forward genetic screen. High throughput screening with fetal ultrasound imaging followed by whole exome sequencing analysis recovered a preponderance of cilia related genes and cilia transduced cell signaling genes among mutations identified to cause CHD. The perturbation of left-right patterning in CHD pathogenesis is suggested by the association of CHD with heterotaxy, but also by the finding of the co-occurrence of laterality defects with CHD in birth defect registries. Many of the cilia and cilia cell signaling genes recovered were found to be related to Hedgehog signaling. Studies in mice showed cilia transduced hedgehog signaling coordinates left-right patterning with heart looping and differentiation of the heart tube. Cilia transduced Shh signaling also regulates later events in heart development, including outflow tract septation and formation of the atrioventricular septum. More recent work has shown mutations in cilia related genes may also contribute to valve disease that largely manifest in adult life. Overall, these and other findings show cilia play an important role in CHD and also in more common valve diseases.

SCO-Spondin Defects and Neuroinflammation Are Conserved Mechanisms Driving Spinal Deformity across Genetic Models of Idiopathic Scoliosis

Adolescent idiopathic scoliosis (AIS) affects 3% to 4% of children between the ages of 11 and 18 [1, 2]. This disorder, characterized by abnormal three-dimensional spinal curvatures that typically develop during periods of rapid growth, occurs in the absence of congenital vertebral malformations or neuromuscular defects [1]. Genetic heterogeneity [3] and a historical lack of appropriate animal models [4] have confounded basic understanding of AIS biology; thus, treatment options remain limited [5, 6]. Recently, genetic studies using zebrafish have linked idiopathic-like scoliosis to irregularities in motile cilia-mediated cerebrospinal fluid flow [7-9]. However, because loss of cilia motility in human primary ciliary dyskinesia patients is not fully associated with scoliosis [10, 11], other pathogenic mechanisms remain to be determined. Here, we demonstrate that zebrafish scospondin (sspo) mutants develop late-onset idiopathic-like spinal curvatures in the absence of obvious cilia motility defects. Sspo is a large secreted glycoprotein functionally associated with the subcommissural organ and Reissner's fiber [12]-ancient and enigmatic organs of the brain ventricular system reported to govern cerebrospinal fluid homeostasis [13, 14], neurogenesis [12, 15-18], and embryonic morphogenesis [19]. We demonstrate that irregular deposition of Sspo within brain ventricles is associated with idiopathic-like scoliosis across diverse genetic models. Furthermore, Sspo defects are sufficient to induce oxidative stress and neuroinflammatory responses implicated in AIS pathogenesis [9]. Through screening for chemical suppressors of sspo mutant phenotypes, we also identify potent agents capable of blocking severe juvenile spine deformity. Our work thus defines a new preclinical model of AIS and provides tools to realize novel therapeutic strategies.

CFAP300: Mutations in Slavic Patients with Primary Ciliary Dyskinesia and a Role in Ciliary Dynein Arms Trafficking

Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous hereditary disease from a class of ciliopathies. In spite of the recent progress, the genetic basis of PCD in one-third of patients remains unknown. In search for new genes and/or mutations, whole-exome sequencing was performed in 120 unrelated Polish patients with PCD, in whom no genetic cause of PCD was earlier identified. Among a number of pathogenic variants in PCD genes, mutations in CFAP300 (alias C11orf70) were detected. Extended screening in the whole Polish PCD cohort revealed the relatively high frequency (3.6%) of otherwise rare c.[198_200 del_insCC] variant, indicating that it should be included in population-specific genetic tests for PCD in Slavic populations. Immunofluorescence analysis of the respiratory epithelial cells from patients with CFAP300 mutations revealed the absence or aberrant localization of outer and inner dynein arm markers, consistent with transmission electron microscope images indicating the lack of both dynein arms. Interestingly, the disparate localization of DNAH5 and DNALI1 proteins in patients with CFAP300 mutations suggested differential mechanisms for the trafficking of preassembled outer and inner dynein arms to the axoneme. The profile of CFAP300 expression during ciliogenesis in suspension culture was consistent with its role in cilia assembly. Gene silencing experiments, performed in a model organism, Schmidtea mediterranea (flatworm), pointed to the conserved role of CFAP300 in ciliary function.

Pulmonary non-tuberculous mycobacterial infections: current state and future management

Currently, there is a trend of increasing incidence in pulmonary non-tuberculous mycobacterial infections (PNTM) together with a decrease in tuberculosis (TB) incidence, particularly in developed countries. The prevalence of PNTM in underdeveloped and developing countries remains unclear as there is still a lack of detection methods that could clearly diagnose PNTM applicable in these low-resource settings. Since non-tuberculous mycobacteria (NTM) are environmental pathogens, the vicinity favouring host-pathogen interactions is known as important predisposing factor for PNTM. The ongoing changes in world population, as well as socio-political and economic factors, are linked to the rise in the incidence of PNTM. Development is an important factor for the improvement of population well-being, but it has also been linked, in general, to detrimental environmental consequences, including the rise of emergent (usually neglected) infectious diseases, such as PNTM. The rise of neglected PNTM infections requires the expansion of the current efforts on the development of diagnostics, therapies and vaccines for mycobacterial diseases, which at present, are mainly focused on TB. This review discuss the current situation of PNTM and its predisposing factors, as well as the efforts and challenges for their control.

International consensus guideline for reporting transmission electron microscopy results in the diagnosis of primary ciliary dyskinesia (BEAT PCD TEM Criteria)

Primary ciliary dyskinesia (PCD) is a heterogeneous genetic condition. European and North American diagnostic guidelines recommend transmission electron microscopy (TEM) as one of a combination of tests to confirm a diagnosis. However, there is no definition of what constitutes a defect or consensus on reporting terminology. The aim of this project was to provide an internationally agreed ultrastructural classification for PCD diagnosis by TEM.A consensus guideline was developed by PCD electron microscopy experts representing 18 centres in 14 countries. An initial meeting and discussion were followed by a Delphi consensus process. The agreed guideline was then tested, modified and retested through exchange of samples and electron micrographs between the 18 diagnostic centres.The final guideline a) provides agreed terminology and a definition of Class 1 defects which are diagnostic for PCD; b) identifies Class 2 defects which can indicate a diagnosis of PCD in combination with other supporting evidence; c) describes features which should be included in a ciliary ultrastructure report to assist multidisciplinary diagnosis of PCD; and d) defines adequacy of a diagnostic sample.This tested and externally validated statement provides a clear guideline for the diagnosis of PCD by TEM which can be used to standardise diagnosis internationally.

Exacerbations and Pseudomonas aeruginosa colonization are associated with altered lung structure and function in primary ciliary dyskinesia

BACKGROUND

Recurrent bacterial infections of the respiratory tract are one of the major clinical features of the primary ciliary dyskinesia (PCD), a rare genetic disease due to malfunctioning of motile cilia. Chronic infections and persistent inflammation of the respiratory system result in progressive lung disease. Aim of the study was to highlight the main factors associated with clinical, functional and anatomical deterioration in PCD patients.

METHODS

We retrospectively analyzed data from 58 patients with PCD, 37 adults and 21 children. The demographic and clinical data, forced expiratory volume at 1 s (FEV1) and forced vital capacity (FVC), sputum microbiology and imaging results (chest CT scores-modified Bhalla) were recorded. Patients were stratified according to the number of exacerbations (< 2/year vs ≥ 2/year) and chronic Pseudomonas aeruginosa (PA) colonization. The possible correlations between lung function and chest CT scores were assessed; we also evaluated the correlation between these parameters and the severity scores for bronchiectasis (BSI, FACED and e-FACED).

RESULTS

Chest CT scores showed a significant correlation with FEV1 (p = 0.0002), age (p <  0.0001), BMI (p = 0.0002) and number of lung lobes involved (p <  0.0001). PA colonization had an overall prevalence of 32.6%: no significant difference in FEV1 between PA colonized and non-colonized patients was found (p = 0.70), while chest CT score was significantly worse in chronic PA colonized patients (p = 0.009). Patients with a high number of exacerbation (≥ 2/year) were older (p = 0.01), had lower FEV1 (p = 0.03), greater number of lobes involved (p < 0.001) and worse CT score than patients with low number of exacerbations (p = 0.001); they also had higher prevalence of PA chronic bronchial infection (33.3% versus 13.6%, p = 0.10). Multivariable linear regression analyses adjusted for gender, age and BMI showed positive associations between PA colonization and number of exacerbations with severity of disease (number of lobes involved, CT score, BSI, FACED, and e-FACED).

CONCLUSIONS

In our PCD population the number of exacerbations (≥ 2/year) and PA colonization were the two most relevant factors associated with severity of disease.

Sperm capacitation is associated with phosphorylation of the testis-specific radial spoke protein Rsph6a†

Mammalian sperm undergo a series of biochemical and physiological changes collectively known as capacitation in order to acquire the ability to fertilize. Although the increase in phosphorylation associated with mouse sperm capacitation is well established, the identity of the proteins involved in this signaling cascade remains largely unknown. Tandem mass spectrometry (MS/MS) has been used to identify the exact sites of phosphorylation and to compare the relative extent of phosphorylation at these sites. In the present work, we find that a novel site of phosphorylation on a peptide derived from the radial spoke protein Rsph6a is more phosphorylated in capacitated mouse sperm. The Rsph6a gene has six exons, five of which are conserved during evolution in flagellated cells. The exon containing the capacitation-induced phosphorylation site was found exclusively in eutherian mammals. Transcript analyses revealed at least two different testis-specific splicing variants for Rsph6a.Rsph6a mRNA expression was restricted to spermatocytes. Using antibodies generated against the Rsph6a N-terminal domain, western blotting and immunofluorescence analyses indicated that the protein remains in mature sperm and localizes to the sperm flagellum. Consistent with its role in the axoneme, solubility analyses revealed that Rsph6 is attached to cytoskeletal structures. Based on previous studies in Chlamydomonas reinhardtii, we predict that Rsph6 participates in the interaction between the central pair of microtubules and the surrounding pairs. The findings that Rsph6a is more phosphorylated during capacitation and is predicted to function in axonemal localization make Rsph6a a candidate protein mediating signaling processes in the sperm flagellum.

Non-CF bronchiectasis: Orphan disease no longer

Bronchiectasis is a complex, chronic respiratory condition, characterized by frequent cough and exertional dyspnea due to a range of conditions that include inherited mucociliary defects, inhalational airway injury, immunodeficiency states and prior respiratory infections. For years, bronchiectasis was classified as either being caused by cystic fibrosis or non-cystic fibrosis. Non-cystic fibrosis bronchiectasis, once considered an orphan disease, is more prevalent worldwide in part due to greater availability of chest computed tomographic imaging. Identification of the cause of non-cystic fibrosis bronchiectasis with the use of chest imaging, laboratory testing, and microbiologic assessment of airway secretions can lead to initiation of specific therapies aimed at slowing disease progression. Nonpharmacologic therapies such as airway clearance techniques and pulmonary rehabilitation improve patient symptoms. Inhaled corticosteroids should not be routinely prescribed unless concomitant asthma or COPD is present. Inhaled antibiotics prescribed to individuals with >3 exacerbations per year are well tolerated, reduce airway bacteria load and may reduce the frequency of exacerbations. Likewise, chronic macrolide therapy reduces the frequency of exacerbations. Medical therapies for cystic fibrosis bronchiectasis may not be effective in treatment of non-cystic fibrosis bronchiectasis.

Airway Epithelial Dynamics in Allergy and Related Chronic Inflammatory Airway Diseases

Allergic rhinitis, chronic rhinosinusitis, and asthma are highly prevalent, multifactorial chronic airway diseases. Several environmental and genetic factors affect airway epithelial dynamics leading to activation of inflammatory mechanisms in the airways. This review links environmental factors to host epithelial immunity in airway diseases. Understanding altered homeostasis of the airway epithelium might provide important targets for diagnostics and therapy of chronic airway diseases.

Mice with a Deletion of Rsph1 Exhibit a Low Level of Mucociliary Clearance and Develop a Primary Ciliary Dyskinesia Phenotype

Primary ciliary dyskinesia (PCD) is a genetically and phenotypically heterogeneous disease caused by mutations in over 40 different genes. Individuals with PCD caused by mutations in RSPH1 (radial spoke head 1 homolog) have been reported to have a milder phenotype than other individuals with PCD, as evidenced by a lower incidence of neonatal respiratory distress, higher nasal nitric oxide concentrations, and better lung function. To better understand genotype-phenotype relationships in PCD, we have characterized a mutant mouse model with a deletion of Rsph1. Approximately 50% of cilia from Rsph1^-/- cells appeared normal by transmission EM, whereas the remaining cilia revealed a range of defects, primarily transpositions or a missing central pair. Ciliary beat frequency in Rsph1^-/- cells was significantly lower than in control cells (20.2 ± 0.8 vs. 25.0 ± 0.9 Hz), and the cilia exhibited an aberrant rotational waveform. Young Rsph1^-/- animals demonstrated a low rate of mucociliary clearance in the nasopharynx that was reduced to zero by about 1 month of age. Rsph1^-/- animals accumulated mucus in the nasal cavity but had a lower bacterial burden than animals with a deletion of dynein axonemal intermediate chain 1 (Dnaic1^-/-). Thus, Rsph1^-/- mice display a PCD phenotype similar to but less severe than that observed in Dnaic1^-/- mice, similar to what has been observed in humans. The results suggest that some individuals with PCD may not have a complete loss of mucociliary clearance and further suggest that early diagnosis and intervention may be important to maintain this low amount of clearance.

Knowledge of Rare Respiratory Diseases among Paediatricians and Medical School Students

Alpha-1-antitrypsin deficiency (AATD) and primary ciliary dyskinesia (PCD) are underdiagnosed rare diseases showing a median diagnostic delay of five to ten years, which has negative effects on patient prognosis. Lack of awareness and education among healthcare professionals involved in the management of these patients have been suggested as possible causes. Our aim was to assess knowledge of these diseases among paediatricians and medical school students to determine which knowledge areas are most deficient. A survey was designed with questions testing fundamental aspects of the diagnosis and treatment of AATD and PCD. A score equal to or greater than 50% of the maximum score was set as the level necessary to ensure a good knowledge of both diseases. Our results indicate a profound lack of knowledge of rare respiratory diseases among paediatric professionals and medical students, suggesting that it is necessary to increase rare respiratory diseases training among all physicians responsible for suspecting and diagnosing them; this will allow early diagnosis and the setup of preventive measures and appropriate early-stage treatment. The first step in closing this knowledge gap could be to include relevant material in the medical syllabus.

Understanding Primary Ciliary Dyskinesia: Experience From a Mediterranean Diagnostic Reference Centre

Background: Due to the lack of a gold standard diagnostic test, reference centres with experienced personnel and costly procedures are needed for primary ciliary dyskinesia (PCD) diagnostics. Diagnostic flowcharts always start with clinical symptoms. Therefore, the aim of this work is to define differential clinical criteria so that only patients clinically compatible with PCD are referred to reference centres. Materials and methods: 18 variables from 476 Mediterranean patients with clinically suspicious PCD were collected. After analysing cilia function and ultrastructure, 89 individuals were diagnosed with PCD and 387 had a negative diagnosis. Simple logistic regression analysis, considering PCD as a dependent variable and the others as independent variables, was done. In order to define the variables that best explain PCD, a step-wise logistic regression model was defined. Aiming to classify individuals as PCD or PCD-like patients, based on variables included in the study, a classification and regression tree (CART) was designed. Results and conclusions: Simple logistic regression analysis shows statistically significant association between age at the beginning of their symptomatology, periodicity, fertility, situs inversus, recurrent otitis, atelectasis, bronchiectasis, chronic productive cough, rhinorrea, rhinusinusitis and recurrent pneumonias, and PCD. The step-wise logistic regression model selected situs inversus, atelectasis, rhinorrea, chronic productive cough, bronchiectasis, recurrent pneumonias, and otitis as PCD predictive variables (82% sensitivity, 88% specificity, and 0.92 Area Under the Curve (AUC)). A decision tree was designed in order to classify new individuals based on pansinusitis, situs inversus, periodicity, rhinorrea, bronchiectasis, and chronic wet cough.

Patients with severe asthenoteratospermia carrying SPAG6 or RSPH3 mutations have a positive pregnancy outcome following intracytoplasmic sperm injection

PURPOSE

To investigate the relation between mutations in ciliopathy-related SPAG6 and RSPH3 and male infertility with severe asthenoteratospermia characterized by multiple flagellar malformations and reveal the intracytoplasmic sperm injection (ICSI) outcomes of those primary ciliary dyskinesia (PCD) patients.

METHODS

Whole-exome sequencing was applied to identify the pathogenic genes for the five PCD patients. The ICSI outcomes of those patients were compared with eight DNAH1-mutated patients and 215 oligo-asthenospermia (OAT) patients.

RESULTS

We identified, for the first time, the compound heterozygous SPAG6 mutations (c.143_145del: p.48_49del, c.585delA: p.Lys196Serfs*6) in a sporadic PCD patient. Further, a novel homozygous nonsynonymous RSPH3 mutation (c.C799T: p.Arg267Cys) was identified in another PCD patient with consanguineous parents. The pathogenicity of these mutations in the assembly of sperm flagella was confirmed by flagellar ultrastructure analysis, immunofluorescence, and quantitative real-time PCR. All five patients underwent six ICSI cycles. The fertilization rate, blastocyst development rate, and clinical pregnancy rate were 69.3%, 50.0%, and 66.7%, respectively. Four of the five couples, including the subjects carrying mutations in SPAG6 or RSPH3, got healthy children born after ICSI. Additionally, the ICSI outcomes of the five PCD couples were statistically comparable with those of the eight DNAH1-mutated couples and the 215 OAT couples.

CONCLUSIONS

Mutations in ciliopathy-related SPAG6 and RSPH3 cause severe asthenoteratospermia characterized by multiple flagellar malformations, resulting in sterility. ICSI is an optimal management with a positive pregnancy outcome.

Copy number variation in DRC1 is the major cause of primary ciliary dyskinesia in the Japanese population

BACKGROUND

Primary ciliary dyskinesia (PCD) is a rare genetic disorder caused by functional impairment of cilia throughout the body. The involvement of copy number variation (CNV) in the development of PCD is largely unknown.

METHODS

We examined 93 Japanese patients with clinically suspected PCD from 84 unrelated families. CNV was examined either by exome sequencing of a PCD gene panel or by whole-exome sequencing (WES). The identified alterations were validated by PCR and Sanger sequencing. Nasal ciliary ultrastructure was examined by electron microscopy.

RESULTS

Analysis of CNV by the panel or WES revealed a biallelic deletion in the dynein regulatory complex subunit 1 (DRC1) gene in 21 patients, which accounted for 49% of the PCD patients in whom a disease-causing gene was found. Sanger sequencing of the PCR product revealed a 27,748-bp biallelic deletion including exons 1-4 of DRC1 with identical breakpoints in all 21 patients. The ciliary ultrastructure of the patients with this CNV showed axonemal disorganization and the loss or gain of central microtubules.

CONCLUSION

The deletion of DRC1 is the major cause of PCD in Japan and this alteration can cause various ciliary ultrastructural abnormalities.

Fractional Exhaled Nitric Oxide (FENO) in the management of asthma: a position paper of the Italian Respiratory Society (SIP/IRS) and Italian Society of Allergy, Asthma and Clinical Immunology (SIAAIC)

Asthma prevalence in Italy is on the rise and is estimated to be over 6% of the general population. The diagnosis of asthma can be challenging and elusive, especially in children and the last two decades has brought evidences that asthma is not a single disease but consists of various phenotypes. Symptoms can be underestimated by the patient or underreported to the clinician and physical signs can be scanty. Usual objective measures, like spirometry, are necessary but sometimes not significant. Despite proper treatment, asthma can be a very severe condition (even leading to death), however new drugs have recently become available which can be very effective in its control. Since asthma is currently thought to be caused by inflammation, a direct measure of the latter can be of paramount importance. For this purpose, the measurement of Fractional Exhaled Nitric Oxide (FE_NO) has been used since the early years of the current century as a non-invasive, easy-to-assess tool useful for diagnosing and managing asthma. This SIP-IRS/SIAAIC Position Paper is a narrative review which summarizes the evidence behind the usefulness of FE_NO in the diagnosis, management and phenotypization of asthma.

Genotype and phenotype evaluation of patients with primary ciliary dyskinesia: First results from Turkey

BACKGROUND AND OBJECTIVE

Primary ciliary dyskinesia (PCD) is a rare and genetically heterogeneous disease and the severity of the disease related with genetic analysis has been described in some previous studies. The main aim of our study was to describe the clinical characteristics and laboratory findings of patients with genetically diagnosed PCD and to investigate the correlation between clinical, radiologic, and laboratory findings and genetic analyses of these patients.

METHOD

This is a cohort study in which we analyzed the clinical characteristics, laboratory findings, and genetic results of 46 patients with genetically diagnosed PCD through whole-exome sequencing at our single center from a total of 265 patients with PCD within a 5-year period.

RESULTS

Genetic analysis revealed pathogenic variants in DNAH5 (n = 12 individuals, 12 families), CCDC40 (n = 9 individuals, six families), RSPH4A (n = 5 individuals, three families), DNAH11 (n = 4 individuals, four families), HYDIN (n = 5 individuals, five families), CCNO (n = 4 individuals, four families), DNAI1 (n = 2 individuals, one family), ARMC4 (n = 2 individuals, two families), TTC25 (n = 1), DNAH1 (n = 1), and CCDC39 (n = 1) genes. Although not statistically significant, the age at diagnosis was lower (median: 3 years; range, 6 months-4 years) in patients with CCNO pathogenic variants due to the early reporting of symptoms, and the median body mass index (BMI) and BMI z scores were lower in patients at 18.7 and 16 kg/m² , and -0.78 and -1.2 with CCDC40 and CCNO pathogenic variants, respectively. The median forced expiratory flow in 1 second (FEV1%), forced vital capacity (FVC%), and forced expiratory flow (FEF)25-75% were 53%, 64%, and 28%, respectively; these parameters were also lower in the CCDC40 group than in the other groups. There was no significant correlation between the genetic results and symptoms, radiologic findings, and microbiologic data of patients with PCD.

CONCLUSION

In PCD, there was significant heterogeneity of lung disease, patients who had pathogenic variants in CCNO presented earlier, and those with CCDC40 and CCNO had worse lung disease, and poorer nutritional status compared with the other subgroups. We hope that whole genotype-phenotype and clinical relationships will be identified in PCD.

Evaluation of the pulmonary radioaerosol mucociliary clearance scan as an adjunctive test for the diagnosis of primary ciliary dyskinesia in children

INTRODUCTION

The accuracy of primary ciliary dyskinesia (PCD) diagnosis has improved but no single test is diagnostic and some cases remain unsolved. Data regarding the accuracy of pulmonary radioaerosol mucociliary clearance scan (PRMCC) for the diagnosis of PCD are limited to predominantly adults using a 24-hour test. This study was performed to determine the accuracy of a 60-minute PRMCC test for diagnosing PCD in children.

METHODS

Children with suspected PCD and inconclusive clinical diagnostic testing in an expert center were selected for PRMCC testing. Nebulized ^99m Tc sulfur colloid was inhaled and dynamic imaging acquired for 60 to 120 minutes. Two independent radiologists blinded to the clinical diagnosis and health records overread PRMCC studies. The PRMCC result was compared with the reference standard diagnosis of PCD made by two physicians using the cumulative health record, blinded to PRMCC results.

RESULTS

From 2008 to 2018, 57 patients (6-17 years) participated, of which 16 met criteria for the reference diagnosis of PCD. The PRMCC test was conclusive in 54 patients (94.7%) and had a sensitivity of 100% (95% confidence interval [CI] = 78.2-100), specificity of 85.7% (95% CI = 69.7-95.2), positive predictive value of 75% (95% CI = 57.1-87.1), negative predictive value of 100% (95% CI = 90.2-100), and accuracy of 90% (95% CI = 78.2-96.7).

CONCLUSION

The 60-minute PRMCC test is noninvasive and feasible in children with a high negative predictive value for PCD. It may be a helpful adjunctive test to rule out PCD when clinical suspicion remains after guideline recommended first-line clinical testing.

Frequency of Cystic Fibrosis Transmembrane Conductance Regulator Variants in Individuals Evaluated for Primary Ciliary Dyskinesia

OBJECTIVE

To evaluate whether cystic fibrosis transmembrane conductance regulator (CFTR) variants are more common among individuals tested for primary ciliary dyskinesia (PCD) compared with controls.

STUDY DESIGN

Data were studied from 1021 individuals with commercial genetic testing for suspected PCD and 91 777 controls with genetic testing at the same company (Invitae) for symptoms/diseases unrelated to PCD or CFTR testing. The prevalence of CFTR variants was compared between controls and each of 3 groups of individuals tested for PCD (PCD-positive, -uncertain, and -negative molecular diagnosis).

RESULTS

The prevalence of 1 pathogenic CFTR variant was similar among the individual groups. When combining the PCD-uncertain and PCR-negative molecular diagnosis groups, there was a higher prevalence of single pathogenic CFTR variants compared with controls (P = .03). Importantly, >1% of individuals who had negative genetic testing results for PCD had 2 pathogenic CFTR variants (8 of 723), and the incidence of cystic fibrosis (CF) (2 pathogenic variants) is roughly 1 in 3000 individuals of Caucasian ethnicity (∼0.03%). This incidence was also greater than that of 2 pathogenic CFTR variants in the control population (0.09% [84 of 91 777]; P = 9.60 × 10^-16). These variants correlate with mild CFTR-related disease.

CONCLUSIONS

Our results suggest that a single pathogenic CFTR variant is not likely to be a PCD-mimetic, but ongoing studies are needed in individuals in whom PCD is suspected and genetic testing results are uncertain or negative. Furthermore, CF may be misdiagnosed as PCD, reflecting phenotypic overlap. Among individuals evaluated for PCD, CF should be considered in the differential even in the CF newborn screening era.

Deep phenotyping, including quantitative ciliary beating parameters, and extensive genotyping in primary ciliary dyskinesia

Background

Primary ciliary dyskinesia (PCD) is a rare genetic disorder resulting in abnormal ciliary motility/structure, extremely heterogeneous at genetic and ultrastructural levels. We aimed, in light of extensive genotyping, to identify specific and quantitative ciliary beating anomalies, according to the ultrastructural phenotype.

Methods

We prospectively included 75 patients with PCD exhibiting the main five ultrastructural phenotypes (n=15/group), screened all corresponding PCD genes and measured quantitative beating parameters by high-speed video-microscopy (HSV).

Results

Sixty-eight (91%) patients carried biallelic mutations. Combined outer/inner dynein arms (ODA/IDA) defect induces total ciliary immotility, regardless of the gene involved. ODA defect induces a residual beating with dramatically low ciliary beat frequency (CBF) related to increased recovery stroke and pause durations, especially in case of DNAI1 mutations. IDA defect with microtubular disorganisation induces a low percentage of beating cilia with decreased beating angle and, in case of CCDC39 mutations, a relatively conserved mean CBF with a high maximal CBF. Central complex defect induces nearly normal beating parameters, regardless of the gene involved, and a gyrating motion in a minority of ciliated edges, especially in case of RSPH1 mutations. PCD with normal ultrastructure exhibits heterogeneous HSV values, but mostly an increased CBF with an extremely high maximal CBF.

Conclusion

Quantitative HSV analysis in PCD objectives beating anomalies associated with specific ciliary ultrastructures and genotypes. It represents a promising approach to guide the molecular analyses towards the best candidate gene(s) to be analysed or to assess the pathogenicity of the numerous sequence variants identified by next-generation-sequencing.

The biology of pulmonary exacerbations in bronchiectasis

Bronchiectasis is a heterogeneous chronic disease. Heterogeneity characterises bronchiectasis not only in the stable state but also during exacerbations, despite evidence on clinical and biological aspects of bronchiectasis, exacerbations still remain poorly understood.Although the scientific community recognises that bacterial infection is a cornerstone in the development of bronchiectasis, there is a lack of data regarding other trigger factors for exacerbations. In addition, a huge amount of data suggest a primary role of neutrophils in the stable state and exacerbation of bronchiectasis, but the inflammatory reaction involves many other additional pathways. Cole's vicious cycle hypothesis illustrates how airway dysfunction, airway inflammation, infection and structural damage are linked. The introduction of the concept of a "vicious vortex" stresses the complexity of the relationships between the components of the cycle. In this model of disease, exacerbations work as a catalyst, accelerating the progression of disease. The roles of microbiology and inflammation need to be considered as closely linked and will need to be investigated in different ways to collect samples. Clinical and translational research is of paramount importance to achieve a better comprehension of the pathophysiology of bronchiectasis, microbiology and inflammation both in the stable state and during exacerbations.

Primary ciliary dyskinesia in the genomics age

Primary ciliary dyskinesia is a genetically and clinically heterogeneous syndrome. Impaired function of motile cilia causes failure of mucociliary clearance. Patients typically present with neonatal respiratory distress of unknown cause and then continue to have a daily wet cough, recurrent chest infections, perennial rhinosinusitis, otitis media with effusion, and bronchiectasis. Approximately 50% of patients have situs inversus, and infertility is common. While understanding of the underlying genetics and disease mechanisms have substantially advanced in recent years, there remains a paucity of evidence for treatment. Next-generation sequencing has increased gene discovery, and mutations in more than 40 genes have been reported to cause primary ciliary dyskinesia, with many other genes likely to be discovered. Increased knowledge of cilia genes is challenging perceptions of the clinical phenotype, as some genes reported in the last 5 years are associated with mild respiratory disease. Developments in genomics and molecular medicine are rapidly improving diagnosis, and a genetic cause can be identified in approximately 70% of patients known to have primary ciliary dyskinesia. Groups are now investigating novel and personalised treatments, although gene therapies are unlikely to be available in the near future.

Therapeutic perspectives for structural and functional abnormalities of cilia

Ciliopathies are a group of hereditary disorders that result from structural or functional abnormalities of cilia. Recent intense research efforts have uncovered the genetic bases of ciliopathies, and our understanding of the assembly and functions of cilia has been improved significantly. Although mechanism-specific therapies for ciliopathies have not yet received regulatory approval, the use of innovative therapeutic modalities such as oligonucleotide therapy, gene replacement therapy, and gene editing in addition to symptomatic treatments are expected to provide valid treatment options in the near future. Moreover, candidate chemical compounds for developing small molecule drugs to treat ciliopathies have been identified. This review introduces the key features of cilia and ciliopathies, and summarizes the advances as well as the challenges that remain with the development of therapies for treating ciliopathies.

Syndromic infertility

Infertility due to genetic mutations that cause other defects, besides infertility, is defined as syndromic. Here we describe three of these disorders for which we perform genetic tests. 1) Hypopituitarism is an endocrine syndrome characterized by reduced or absent secretion of one or more anterior pituitary hormones with consequent dysfunction of the corresponding peripheral glands. Deficiencies in all the hormones is defined as pan-hypopituitarism, lack of two or more hormones is called partial hypopituitarism, whereas absence of a single hormone is defined as selective hypopituitarism. Pan-hypopituitarism is the rarest condition, whereas the other two are more frequent. Several forms exist: congenital, acquired, organic and functional. 2) The correct functioning of the hypothalamic-pituitary-gonadal axis is fundamental for sexual differentiation and development during fetal life and puberty and for normal gonad function. Alteration of the hypothalamic-pituitary system can determine a condition called hypogonadotropic hypogonadism, characterized by normal/low serum levels of the hormones FSH and LH. 3) Primary ciliary dyskinesia is frequently associated with infertility in males because it impairs sperm motility (asthenozoospermia). Primary ciliary dyskinesia is a group of genetically and phenotypically heterogeneous disorders that show morpho-structural alterations of the cilia. Adult women with primary ciliary dyskinesia can be subfertile and have an increased probability of extra-uterine pregnancies. This is due to delayed transport of the oocyte through the uterine tubes. (www.actabiomedica.it)

Three-Dimensional Numerical Analysis of Periciliary Liquid Layer: Ciliary Abnormalities in Respiratory Diseases

Human pulmonary epithelial cells are protected by two layers of fluid—the outer watery periciliary liquid layer (PCL) and the uppermost non-Newtonian mucus layer (ML). Aerosols and inhaled toxic particles are trapped by the ML which must then be removed swiftly to avoid adverse health implications. Epithelial cells are covered with cilia that beat rapidly within the PCL. Such ciliary motion drives the mucus transport. Although cilia can penetrate slightly inside the mucus to assist mucus movement, the motion of the underlying PCL layer within the airway surface liquid (ASL) is significant in mucus and pathogens transport. As such, a detailed parametric study of the influence of different abnormal cilia characteristics, such as low beating frequency, short length, abnormal beating pattern, reduced ciliary density, and epithelium patchiness due to missing cilia on the PCL transport, is carried out numerically. Such abnormalities are found in various chronic respiratory diseases. In addition, the shear stress at the epithelium is assessed due to the importance of shear stress on the epithelial function. Using the immersed boundary (IB) method combined with the finite-difference projection method, we found that the PCL, under standard healthy conditions, has net forward motion but that different diseased conditions decrease the forward motion of the PCL, as is expected based on clinical understanding.

Prevalence and course of disease after lung resection in primary ciliary dyskinesia: a cohort & nested case-control study

Background

Lung resection is a controversial and understudied therapeutic modality in Primary Ciliary Dyskinesia (PCD). We assessed the prevalence of lung resection in PCD across countries and compared disease course in lobectomised and non-lobectomised patients.

Methods

In the international iPCD cohort, we identified lobectomised and non-lobectomised age and sex-matched PCD patients and compared their characteristics, lung function and BMI cross-sectionally and longitudinally.

Results

Among 2896 patients in the iPCD cohort, 163 from 20 centers (15 countries) underwent lung resection (5.6%). Among adult patients, prevalence of lung resection was 8.9%, demonstrating wide variation among countries. Compared to the rest of the iPCD cohort, lobectomised patients were more often females, older at diagnosis, and more often had situs solitus. In about half of the cases (45.6%) lung resection was performed before presentation to specialized PCD centers for diagnostic work-up. Compared to controls (n = 197), lobectomised patients had lower FVC z-scores (− 2.41 vs − 1.35, p = 0.0001) and FEV1 z-scores (− 2.79 vs − 1.99, p = 0.003) at their first post-lung resection assessment. After surgery, lung function continued to decline at a faster rate in lobectomised patients compared to controls (FVC z-score slope: − 0.037/year Vs − 0.009/year, p = 0.047 and FEV1 z-score slope: − 0.052/year Vs − 0.033/year, p = 0.235), although difference did not reach statistical significance for FEV1. Within cases, females and patients with multiple lobe resections had lower lung function.

Conclusions

Prevalence of lung resection in PCD varies widely between countries, is often performed before PCD diagnosis and overall is more frequent in patients with delayed diagnosis. After lung resection, compared to controls most lobectomised patients have poorer and continuing decline of lung function despite lung resection. Further studies benefiting from prospective data collection are needed to confirm these findings.

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.

The expanding phenotype of OFD1-related disorders: Hemizygous loss-of-function variants in three patients with primary ciliary dyskinesia

BACKGROUND

OFD1 has long been recognized as the gene implicated in the classic dysmorphology syndrome, oral-facial-digital syndrome type I (OFDSI). Over time, pathogenic variants in OFD1 were found to be associated with X-linked intellectual disability, Joubert syndrome type 10 (JBTS10), Simpson-Golabi-Behmel syndrome type 2 (SGBS2), and retinitis pigmentosa. Recently, OFD1 pathogenic variants have been implicated in primary ciliary dyskinesia (PCD), a disorder of the motile cilia with a phenotype that includes recurrent oto-sino-pulmonary infections, situs abnormalities, and decreased fertility.

METHODS

We describe three male patients with PCD who were found to have hemizygous pathogenic variants in OFD1, further supporting that PCD is part of a clinical spectrum of OFD1-related disorders. In addition, we provide a review of the available clinical literature describing patients with OFD1 variants and highlight the phenotypic variability of OFD1-related disease.

RESULTS

Some individuals with hemizygous OFD1 variants have PCD, either apparently isolated or in combination with other features of OFD1-related disorders.

CONCLUSION

As clinicians consider the presence or absence of conditions allelic at OFD1, PCD should be considered part of the spectrum of OFD1-related disorders. Understanding the OFD1-related disease spectrum may allow for more focused genetic testing and more timely management of treatable sequelae.

Individualized physical training in the therapy of Primary Ciliary Dyskinesia - A case report

Background

Primary Ciliary Dyskinesia (PCD) is an autosomal recessive disease, characterized by ciliary dysfunction and impaired mucociliary clearance. Previous studies have indicated a low physical fitness in PCD patients but currently it is not known whether physical training beneficially affects fitness, inflammatory markers and quality of life.

Case presentation

The patient was a Caucasian male (67.0 kg, 183.3 cm), born in 1984 and was diagnosed with the Kartagener Syndrome (i.e. PCD) right after birth. He was prescribed structured physical training over a period of almost two years (from August 2017-June 2019) and was assessed regularly. Aerobic fitness improved throughout the intervention period, but no systematic changes were observed in inflammatory markers and overall quality of life.

Conclusions

Our data provides reasoning to stress the implementation of structured physical training to enhance physical performance also in the management of PCD.

Prevalence of chronic rhinosinusitis in bronchiectasis patients suspected of ciliary dyskinesia

BACKGROUND

Mucociliary clearance is a main defense mechanism of the airway and is impaired in ciliary dyskinesia. The objective of this study was to evaluate the prevalence of chronic rhinosinusitis (CRS) and its characteristics in bronchiectasis patients suspected of harboring ciliary dyskinesia.

METHODS

Bronchiectasis patients referred to a rhinology clinic for nasal brush biopsy (NBB) were included in this study. NBB was performed using a curettage technique whereby ciliated epithelial cells were obtained from the surface of the inferior nasal turbinate. Results of transmission electron microscopy findings, primary ciliary dyskinesia (PCD) gene (35 genes) analyses (Invitae), and sinus computed tomography (CT) scans were reviewed.

RESULTS

Twenty-three patients (age, 54 ± 2.9 years) were referred for NBB between 2015 and 2018. Thirteen patients (56.5%) met the criteria for diagnosis of CRS. Nineteen patients had ciliary ultrastructural defects. The most common finding was compound cilia (n = 11, 47.8%). Five patients (21.7%) had central microtubule defects (CMD) with higher forced expiratory volume in 1 second (FEV₁ ) at the time of referral than those without CMD (CMD⁺ , 91 ± 3.7%; CMD^- , 73.5 ± 5.7%; p = 0.023). Of 15 subjects with a PCD gene panel, 67% (9 of 15) carried at least 1 gene associated with PCD. Only 1 patient reached diagnosis of PCD. Approximately 50% of non-PCD carriers had a smoking history (p < 0.05). Lund-Mackay scores did not significantly differ between PCD and non-PCD carriers (p = 0.72).

CONCLUSION

Nearly half of bronchiectasis patients referred for NBB had concurrent CRS. The presence of ciliary abnormalities was not amplified in bronchiectasis patients with CRS compared to those without CRS. Extrinsic factors may be related to ciliary structural abnormalities in non-PCD gene carriers.

Case Reports of Situs Inversus Totalis and Dextrocardia in Sprague Dawley Rats

Situs inversus totalis is a condition where there is a transposition of all internal organs from their normal anatomical location. This infrequent and rare congenital condition has been described in several species of mammals. Dextorcardia is a series of conditions associated with an abnormal congenital positioning of the heart, and is often associated with situs inversus totalis. Here we report a case of situs inversus totalis and two cases of dextrocardia identified in Sprague Dawley rats during gross necropsy evaluations at both the Health Sciences North Research Institute (HSNRI) in Canada and Finlay Institute of Vaccine Research and Production in Cuba. The intent of this report is to share our findings and aid in the accumulation of data on these rare conditions.

Functional loss of Ccdc151 leads to hydrocephalus in a mouse model of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder affecting normal structure and function of motile cilia, phenotypically manifested as chronic respiratory infections, laterality defects and infertility. Autosomal recessive mutations in genes encoding for different components of the ciliary axoneme have been associated with PCD in humans and in model organisms. The CCDC151 gene encodes for a coiled-coil axonemal protein that ensures correct attachment of outer dynein arm (ODA) complexes to microtubules. A correct arrangement of dynein arm complexes is required to provide the proper mechanical force necessary for cilia beat. Loss-of-function mutations in CCDC151 in humans leads to PCD disease with respiratory distress and defective left-right body asymmetry. In mice with the Ccdc151Snbl loss-of-function mutation (Snowball mutant), left-right body asymmetry with heart defects have been observed. Here, we demonstrate that loss of Ccdc151 gene function via targeted gene deletion in mice leads to perinatal lethality and congenital hydrocephalus. Microcomputed tomography (microCT) X-ray imaging of Ccdc151-β-galactosidase reporter expression in whole-mount brain and histological analysis show that Ccdc151 is expressed in ependymal cells lining the ventricular brain system, further confirming the role of Ccdc151 dysfunction in hydrocephalus development. Analyzing the features of hydrocephalus in the Ccdc151-knockout animals by microCT volumetric imaging, we observe continuity of the aqueduct of Sylvius, indicating the communicating nature of hydrocephalus in the Ccdc151-knockout animals. Congenital defects in left-right asymmetry and male infertility have been also observed in Ccdc151-null animals. Ccdc151 gene deletion in adult animals results in abnormal sperm counts and defective sperm motility.This article has an associated First Person interview with the joint first authors of the paper.

The impact of mannose-binding lectin polymorphisms on lung function in primary ciliary dyskinesia

OBJECTIVE

Primary ciliary dyskinesia (PCD) is a congenital lung disease that leads to recurrent and chronic lung infection. The resulting inflammation causes lung damage and declines in lung function. Mannose-binding lectin (MBL) is a first line host defense protein of importance for the innate immunity. Polymorphisms in the MBL gene named MBL2 result in unstable and low functional levels MBL proteins. MBL insufficiency is linked to an increased risk of lung infection and to declines in lung function in patients with cystic fibrosis. We investigated whether there is a similar link in patients with PCD.

METHODS

This retrospective longitudinal study included 85 patients with PCD. Diagnostics and age at diagnosis were recorded, complete spirometry data starting at diagnosis, and Pseudomonas aeruginosa infection status over the last 2 years were collected, and the patients were grouped according to MBL2 genotype status (MBL2-sufficient or MBL2-deficient).

RESULTS

MBL-deficient patients were diagnosed almost 3 years earlier than MBL-sufficient patients (median 6.1 vs 8.9 years, P  < 0.05). There were no differences in the first measured spirometry values, but MBL-deficient patients showed greater declines in forced expiratory volume in one sec (FEV₁ ) than patients with MBL sufficiency (z-score: -0.049 per year [95% CI, -0.075; -0.021] vs -0.009 per year [95% CI, -0.033; 0.015]; P = 0.023). No differences were found in forced vital capacity (FVC), FEV₁ /FVC, or infection status.

CONCLUSION

MBL-deficiency, which is associated with MBL2 mutations, was associated with a lower age at diagnosis and with steeper declines in FEV₁ in patients with PCD. This suggests that the MBL genotype might be a disease modifier in PCD.

Seasonal Variation of the Intraepithelial Gland in Camel Epididymis with Special Reference to Autophagosome

The key role of the epididymis is contributing to sperm storage, maturation, and survival. The epididymis of camel has a unique structure called the intraepithelial gland. The present work aimed to investigate the structure of the epididymal intraepithelial gland with special references to the seasonal variation. The samples were collected from the distal part of the corpus epididymes of completely healthy mature camels (Camelus dromedarius) in the breeding and nonbreeding seasons. Tomato lectin-positive material had been demonstrated within the epididymal spermatozoa. Here, we provide the first transmission electron microscopic study for the intraepithelial gland of camel epididymis detecting the autophagy during the nonbreeding season. The autophagosomes originated from the endoplasmic reticulum, surrounding mitochondria, and located mainly next to the basement membrane. This location is probably valuable for subsequent passing of their contents into the interstitium for possible recycling. The histochemical and ultrastructural characteristics of the gland in the breeding season indicated a hyperactive secretory microenvironment enriched with the glycoprotein-producing machinery, which could be controlled by androgens. The present data suggest that the camel intraepithelial gland has a significant impact on the reproductive activity through their secretory microenvironment during the breeding season. Moreover, it recycles the unused organelles or proteins for reuse or to supply energy under stress conditions in the nonbreeding season.

Primary ciliary dyskinesia in Japan: systematic review and meta-analysis

BACKGROUND

Primary ciliary dyskinesia (PCD) is a rare genetic disorder. Although the genetic tests and new diagnostic algorithms have recently been recommended, clinical signs and electron microscope (EM) findings have historically been the mainstays of diagnosis in Asia. To characterize PCD previously reported in Japan, we conducted a systematic review and meta-analysis.

METHODS

A search using MEDLINE, EMBASE, and Japana Centra Revuo Medicina (in Japanese) databases was carried out to identify articles reporting PCD, Kartagener syndrome, or immotile cilia syndrome in Japanese patients and published between 1985 and 2015.

RESULTS

After excluding duplication from 334 reports, we extracted 316 patients according to the criteria. Diagnosis was most frequently made in adulthood (148 patients [46.8%] ≥ 18 years old, 24 patients [7.6%] < 1 year old, 68 patients [21.5%] 1-17 years old and 76 patients [24.1%] lacking information). Of the 230 patients (72.8%) who received EM examination, there were patients with inner dynein arm (IDA) defects (n = 55; 23.9%), outer dynein arm (ODA) defects (14; 6.1%), both ODA and IDA defects (57; 24.8%), other structural abnormalities (25; 10.9%), no abnormalities (4; 1.7%), and no detailed conclusion or description (75; 32.6%).

CONCLUSION

Delayed diagnosis of this congenital disease with high frequency of IDA defects and low frequency of ODA defects appear to be historical features of PCD reported in Japan, when EM was a main diagnostic tool. This review highlights problems experienced in this field, and provides basic information to establish a modernized PCD diagnosis and management system in the future.

Induced Pluripotent Stem Cells for Primary Ciliary Dyskinesia Modeling and Personalized Medicine

Primary ciliary dyskinesia (PCD) is a rare and heterogeneous genetic disorder that affects the structure and function of motile cilia. In the airway epithelium, impaired ciliary motion results in reduced or absent mucociliary clearance that leads to the appearance of chronic airway infection, sinusitis, and bronchiectasis. Currently, there is no effective treatment for PCD, and research is limited by the lack of convenient models to study this disease and investigate innovative therapies. Furthermore, the high heterogeneity of PCD genotypes is likely to hinder the development of a single therapy for all patients. The generation of patient-derived, induced pluripotent stem cells, and their differentiation into airway epithelium, as well as genome editing technologies, could represent major tools for in vitro PCD modeling and for developing personalized therapies. Here, we review PCD pathogenesis and then discuss how human induced pluripotent stem cells could be used to model this disease for the development of innovative, patient-specific biotherapies.

Lung ultrasound in the follow-up of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an airways ciliary defect, making them unable to beat normally. Hence, there is an increase in the incidence of respiratory recurrent infections leading to multiple atelectasis from different lung lobes during the first months of life repeat chest X-ray (CXR) controls with increase of radiation exposure in this younger population. We report the lung ultrasound follow-up of two newborn diagnosed with PCD. The illness in these cases was suspected during the first days of life due to worsening of respiratory distress on previous healthy newborns. Both patients cases show the ability of bedside lung ultrasound (LUS) to confirm clinical suspicion of atelectasis or pneumonia. Using LUS for the diagnosis and follow-up may help in avoiding routine CXR, thus reducing the huge amount of ionizing radiation in these patients.

Developmental and behavioral problems in preschool-aged primary ciliary dyskinesia patients

Primary ciliary dyskinesia (PCD) causes a broad spectrum of disease. This study aims to explore the developmental, behavioral, and social-emotional aspects of preschool-aged children with PCD. Fourteen PCD, 17 cystic fibrosis (CF) patients and 15 healthy subjects were enrolled. Developmental features of the participants were evaluated with Ages and Stages Questionnaire. Parents of participants filled out the Child Behavior Checklist (CBCL). The number of children screened positive for developmental delay was statistically higher in the PCD group. Higher numbers of children with PCD were screened positive for developmental delay in communication and problem-solving domains. Delay in fine motor skill domain was more common in children with PCD and CF compared to healthy subjects. There was no difference among the three groups in terms of gross motor and personal-social development. None of the children in all three groups was shown to have social-emotional problems. In CBCL, patients with CF had higher internalizing problem scores. Externalizing and total problem scores did not differ between the three groups. However, among PCD patients, children with developmental delay on more than one domain had higher externalizing and total problem scores.Conclusion: The current study revealed that positive screening for developmental delay is more common in preschool-aged PCD patients compared to patients with CF and healthy children. What is Known: • Intelligence scores of school-aged PCD patients are similar to healthy subjects despite their higher internalizing problem scores on Child Behavior Checklist (CBCL). • School-aged PCD patients exhibit higher hyperactivity and inattention findings. What is New: • Positive screening for developmental delay in communication, problem-solving and fine motor skills is more common in preschool-aged PCD patients. • Preschool-aged PCD patients screened positive for developmental delay in more than one domain have higher externalizing and total problem scores on CBCL.

Severe pulmonary disease in an adult primary ciliary dyskinesia population in Brazil

Primary Ciliary Dyskinesia (PCD) is underdiagnosed in Brazil. We enrolled patients from an adult service of Bronchiectasis over a two-year period in a cross-sectional study. The inclusion criteria were laterality disorders (LD), cough with recurrent infections and the exclusion of other causes of bronchiectasis. Patients underwent at least two of the following tests: nasal nitric oxide, ciliary movement and analysis of ciliary immunofluorescence, and genetic tests (31 PCD genes + CFTR gene). The clinical characterization included the PICADAR and bronchiectasis scores, pulmonary function, chronic Pseudomonas aeruginosa (cPA) colonization, exhaled breath condensate (EBC) and mucus rheology (MR). Forty-nine of the 500 patients were diagnosed with definite (42/49), probable (5/49), and clinical (2/49) PCD. Twenty-four patients (24/47) presented bi-allelic pathogenic variants in a total of 31 screened PCD genes. A PICADAR score > 5 was found in 37/49 patients, consanguinity in 27/49, LD in 28/49, and eight PCD sibling groups. FACED diagnosed 23/49 patients with moderate or severe bronchiectasis; FEV1 ≤ 50% in 25/49 patients, eight patients had undergone lung transplantation, four had been lobectomized and cPA+ was determined in 20/49. The EBC and MR were altered in all patients. This adult PCD population was characterized by consanguinity, severe lung impairment, genetic variability, altered EBC and MR.

Cost-effectiveness analysis of three algorithms for diagnosing primary ciliary dyskinesia: a simulation study

Background

Primary Ciliary Dyskinesia (PCD) diagnosis relies on a combination of tests which may include (a) nasal Nitric Oxide (nNO), (b) High Speed Video Microscopy (HSVM) and (c) Transmission Electron Microscopy (TEM). There is variability in the availability of these tests and lack of universal agreement whether diagnostic tests should be performed in sequence or in parallel. We assessed three combinations of tests for PCD diagnosis and estimated net sensitivity and specificity as well as cost-effectiveness (CE) and incremental cost-effectiveness (ICE) ratios.

Methods and results

A hypothetical initial population of 1000 referrals (expected 320 PCD patients) was followed through a probabilistic decision analysis model which was created to assess the CE of three diagnostic algorithms (a) nNO + TEM in sequence, (b) nNO + HSVM in sequence and (c) nNO/HSVM in parallel followed, in cases with conflicting results, by confirmatory TEM (nNO/HSVM+TEM). Number of PCD patients identified, CE and ICE ratios were calculated using Monte Carlo simulations. Out of 320 expected PCD patients, 313 were identified by nNO/HSVM+TEM, 274 with nNO + HSVM and 198 with nNO + TEM. The nNO/HSVM+TEM had the highest mean annual cost (€209 K) followed by nNO + TEM (€150 K) and nNO + HSVM (€136 K). The nNO + HSVM algorithm dominated the nNO + TEM algorithm (less costly and more effective). The ICE ratio for nNO/HSVM+TEM was €2.1 K per additional PCD patient identified.

Conclusions

The diagnostic algorithm (nNO/HSVM+TEM) with parallel testing outperforms algorithms with tests in sequence. These findings, can inform the dialogue on the development of evidence-based guidelines for PCD diagnostic testing. Future research in understudied aspects of the disease, such as PCD-related quality of life and PCD-associated costs, is needed to help the better implementation of these guidelines across various healthcare systems.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1116-3) contains supplementary material, which is available to authorized users.

The Progress of CRISPR/Cas9-Mediated Gene Editing in Generating Mouse/Zebrafish Models of Human Skeletal Diseases

Genetic factors play a substantial role in the etiology of skeletal diseases, which involve 1) defects in skeletal development, including intramembranous ossification and endochondral ossification; 2) defects in skeletal metabolism, including late bone growth and bone remodeling; 3) defects in early developmental processes related to skeletal diseases, such as neural crest cell (NCC) and cilia functions; 4) disturbance of the cellular signaling pathways which potentially affect bone growth. Efficient and high-throughput genetic methods have enabled the exploration and verification of disease-causing genes and variants. Animal models including mouse and zebrafish have been extensively used in functional mechanism studies of causal genes and variants. The conventional approaches of generating mutant animal models include spontaneous mutagenesis, random integration, and targeted integration via mouse embryonic stem cells. These approaches are costly and time-consuming. Recent development and application of gene-editing tools, especially the CRISPR/Cas9 system, has significantly accelerated the process of gene-editing in diverse organisms. Here we review both mice and zebrafish models of human skeletal diseases generated by CRISPR/Cas9 system, and their contributions to deciphering the underpins of disease mechanisms.