Primary Ciliary Dyskinesia Research Articles

The SPEC score-Aquantifiable CT scoring system for primary ciliary dyskinesia.

Structural lung changes seen on computed tomography (CT) scans in persons with primary ciliary dyskinesia (pwPCD) are currently described using cystic fibrosis (CF) derived scoring systems. Recent work has shown structural changes and frequencies that are unique to PCD, indicating the need for a unique PCD-derivedscoring system. Chest CT scans from 30 pwPCD, were described for structural changes including bronchiectasis, bronchial wall thickening, mucous plugging, atelectasis, air trapping, and interlobar septal thickening and, additionally, changes previously described as being frequent in pwPCD including extensive tree-in-bud pattern of mucous plugging, bronchoceles or nodules, thickening of interlobar and interlobular septa and whole lobe atelectasis. Based on these findings a novel and unique scoring system, the Specific PCD Evaluation by CT (SPEC) score was constructed. Scans were then re-scored using the SPEC score and results compared to corresponding measurements of lung function to assess structure-function correlation. Total SPEC scores ranged from 0 to 60 (max possible score 90). There was a strong negative correlation between the SPEC score (SPEC) and forced vital capacity (FVC), forced expiratory volume over 1 s(FEV1 ) and FEV1 /FVC ratio (-r = .784, -.865, -.872 respectively). Using PCD-deriveddata we describe the construct of a PCD-specificscore for assessing lung structural damage on CT scans, the SPEC score. A strong correlation between the SPEC score and PFT variables was identified. The SPEC score holds the potential for describing longitudinal changes in CT scans and assessing the efficacy of interventive therapies in patients with PCD.

НОВЫЙ ПРИБОР «СИСТЕМА ОЧИСТКИ ДЫХАТЕЛЬНЫХ ПУТЕЙ YANG KUN YK-800» В КИНЕЗИТЕРАПИИ ДЕТЕЙ С ХРОНИЧЕСКИМИ ЗАБОЛЕВАНИЯМИ ЛЕГКИХ

Cystic fibrosis (CF) and primary ciliary dyskinesia (PCD) in children are both accompanied by copious amounts of infected sputum. Kinesitherapy (KT) eliminates mucostasis by providing bronchial drainage. KT methods are being constantly improved. The purpose of this research was to determine the effectiveness and safety of the new vest airway clearance system (ACS) chest vibration therapy machine model YK800 by Zhengzhou Yangkun Medical Instrument Co., Ltd. (Zhengzhou, China) in children with CF and PCD. The ACS consists of a compressor and a vest and creates high-frequency oscillation of the chest promoting drainage of problematic parts of the respiratory tract, small- and medium-caliber bronchi. Materials and methods used: in a study based on the National Medical Research Center for Children’s Health (Moscow, Russia) the KT included 5 sessions with the Yangkun YK800 in 15 patients aged 5 to 17 y/o: 8 with CF and 7 with PCD. Objective criteria: measurement of external respiratory function (ERF) and saturation, monitoring of chest excursion, and the 6-minute walk test. Subjective criteria: complaints, well-being, comfort. Results: objective criteria - improved ERF indicators in % (FVC p=0.004; r=0.829; FEV1 p=0.023; r=0.973; FEF25% p=0.018; r=0.840; FEF50% p=0.016; r=0.827; FEF75% p=0.015; r=0.867), especially high-speed indicators (FEF25%, FEF50%, FEF75%) that indicate the cleansing of mucus in the medium and small respiratory tracts; saturation improved (p=0.020; r=0.548); chest excursion increased (p=0.002; r=0.779). According to the 6-minute walk test, there was a significant increase in the distance traveled (p=0.000; r=0.535), 13 (86.6%) patients at the end of the course rated it as easier. Subjective criteria - 80% of patients noted sen-sations of productive coughing, easier expectoration of sputum: improvement in general condi-tion - 15, reduction in fatigue - 12, increased physical activity - 12, easier expectoration of phlegm - 13, reduction in episodes of paroxysmal cough - 13. Comfort in the use of the vest was rated at 4.4 points, noting mild vibration. Conclusion: the Yangkun YK800 vest airway clearance system as part of the KT has shown its effectiveness and safety in children with CF and PCD.

Mapping the Most Common Founder Variant in RSPH9 That Causes Primary Ciliary Dyskinesia in Multiple Consanguineous Families of Bedouin Arabs.

Primary ciliary dyskinesia (PCD) is a congenital thoracic disorder caused by dysfunction of motile cilia, resulting in insufficient mucociliary clearance of the lungs. The overall aim of this study is to identify causative defective genes in PCD-affected individuals in the Kuwaiti population. A cohort of multiple consanguineous PCD families was identified from Kuwaiti patients and genomic DNA from the family members was isolated using standard procedures. The DNA samples from all affected individuals were analyzed by whole exome sequencing (WES). Transmission electron microscopy (TEM) and immunofluorescent analysis (IF) were performed on samples obtained by nasal brushings to identify specific structural abnormalities within ciliated cells. Here, we present six multiplex families with 11 patients who all presented with typical PCD symptoms. Ten out of eleven patients inherited a 3 bp homozygous deletion of GAA in RSPH9, whereas the eleventh patients inherited this variant in trans with a frameshift deletion in RSPH9. Genetic results were confirmed by segregation analysis. The in-frame deletion of GAA in RSPH9 has previously been published as pathogenic in both annotated RSPH9 transcript variants (1 and 2). In contrast, the previously unpublished RSPH9 frameshift deletion identified in KU-15.IV2 impacts only RSPH9 transcript variant two. Regarding all 11 PCD individuals analyzed, IF results demonstrated absence of RSPH9 protein and TEM analysis showed the typical findings in RSPH9 mutant individuals. We present the largest cohort of PCD individuals affected by the founder in-frame deletion GAA in RSPH9. This founder variant is the most common PCD-causing variant in Bedouin Arabs in Kuwait.

Clinical and Genetic Characterization of Patients with Primary Ciliary Dyskinesia in Southwest Saudi Arabia: A Cross Sectional Study.

Primary ciliary dyskinesia (PCD, MIM 244400) is an inherited ciliopathy disorder characterized by recurrent sinopulmonary infections, subfertility, and laterality defects. The true incidence of PCD in Saudi Arabia is not known, but it is likely underdiagnosed due to the high prevalence of consanguineous marriages. In this study, we aim to study the clinical and genetic characteristics of PCD patients in the southwestern region of Saudi Arabia to provide guidance to clinicians and researchers studying PCD. This was a cross-sectional study conducted between 2019 and 2023 in Abha Maternity and Children's Hospital. Twenty-eight patients with clinically diagnosed PCD were recruited. The diagnosis of PCD was confirmed via whole-exome sequencing. A total of 28 patients from 20 families were identified and recruited for this study. The median age of patients was 7.5 years (IQR = 3, 13 years). The people of different sexes were evenly distributed, and 18 patients (64%) had neonatal respiratory distress (NRD). The median age of diagnosis was 5.5 years (IQR = 2, 11 years), while the age when the first symptoms appeared was 3 months old (IQR = 1, 6 months). The prevalence of a chronic wet cough, chronic rhinosinusitis, ear infections were 100% (n = 28), 78.6% (n = 22), and 67.9% (19), respectively. The most common gene in our study was DNAH5, which represented 17.9% (five out of twenty-eight) of the cases. Furthermore, the remaining pathogenic variants included: 14.3% with RSPH9 in four individuals (three families), 14.3% with DNAI2 in four individuals (two families), and 10.7% with LRRC56 in three individuals (one family). The most common findings on the chest CT scans were consolidation (seen in all patients), mucus plugging (seen in 95%), and bronchiectasis (seen in 77%). In the patients with bronchiectasis, the most commonly affected lobes were the right lower lobe (88%) and left lower lobe (76%). The patients with PCD and situs inversus were more likely to experience NRD than the patients with PCD and situs solitus. The median PICADAR score in the patients with PCD and situs inversus (median: 11.5; Q1: 10-Q3: 12.5) was significantly higher compared to those with PCD and situs solitus (median: 7.5; Q1: 5.8-Q3: 8) (U = 10.5; p < 0.001). This study provides preliminary data on the clinical and genetic characteristics of PCD patients in the southwestern region of Saudi Arabia. We found that DNAH5 and RSPH9 genes were the most common genes among the studied population. Furthermore, PCD should be considered for each child with early NRD and laterality defects, and further confirmatory tests are recommended. These findings also highlight the need for greater awareness of the disease in daily clinical practice to facilitate early diagnosis and avoid irreversible lung damage.

Cilia-related diseases.

More and more attention is paid to diseases such as internal transfer and brain malformation which are caused by the abnormal morphogenesis of cilia. These cilia-related diseases are divided into two categories: ciliopathy resulting from defects of primary cilia and primary ciliary dyskinesia (PCD) caused by functional dysregulation of motile cilia. Cilia are widely distributed, and their related diseases can cover many human organs and tissues. Recent studies prove that primary cilia play a key role in maintaining homeostasis in the cardiovascular system. However, molecular mechanisms of cilia-related diseases remain elusive. Here, we reviewed recent research progresses on characteristics, molecular mechanisms and treatment methods of ciliopathy and PCD. Our review is beneficial to the further research on the pathogenesis and treatment strategies of cilia-related diseases.

Outer dynein arm docking complex subunit 2 polymorphism rs7893462 modulates hepatocellular carcinoma susceptibility and can serve as an overall survival biomarker for hepatitis B virus-related hepatocellular carcinoma after hepatectomy: a cohort study with a long-term follow-up

BackgroundGenetic variants of outer dynein arm docking complex subunit 2 (ODAD2) have been reported to be closely associated with primary ciliary dyskinesia and colorectal cancer in previous studies, but the association of genetic variants of ODAD2 with hepatocellular carcinoma (HCC) has not been reported.MethodsWe enrolled 80 healthy subjects and 468 Guangxi hepatitis B virus (HBV)-related HCC patients in this study. A case–control study method was used to explore the association of different ODAD2-rs7893462 genotypes with hepatocarcinogenesis. A comprehensive survival analysis was used to explore the association of rs7893462 with the prognosis of HBV-related HCC in Guangxi.ResultsThrough a case–control study, we observed that patients carrying the G allele of rs7893462 had a markedly increased susceptibility to hepatocarcinogenesis (odds ratio = 1.712, 95% confidence interval = 1.032–2.839, P = 0.037). We found that there were significant prognosis differences among three different genotypes of rs7893462. Nomogram analysis suggested that the contribution of rs7893462 polymorphisms to the prognosis of HBV-related HCC was second only to the BCLC stage. Stratified survival analysis suggested that the AG genotype of rs7893462 was an independent prognostic risk factor for HBV-related HCC. Joint effect survival analysis also observed that the AG genotype of rs7893462 combined with clinical parameters could significantly identify HBV-related HCC patients with different prognostic outcomes more accurately, and the AG genotype was also observed to be independent of clinical factors in HBV-related HCC survival.ConclusionThe ODAD2-rs7893462 polymorphisms can be used as an independent prognostic indicator of HBV-related HCC overall survival and are significantly associated with susceptibility to hepatocarcinogenesis.

Nasal Nitric Oxide in Children: A Review of Current Outreach in Pediatric Respiratory Medicine.

Nasal nitric oxide (nNO) is a gas synthesized by the inducible and constitutive NO synthase (NOS) enzyme in the airway cells of the nasal mucosa. Like lung nitric oxide, it is thought to be associated with airway inflammation in various respiratory diseases in children. The aim of our review was to investigate the current state of use of nNO measurement in children. A comprehensive search was conducted using the Web of Science and PubMed databases specifically targeting publications in the English language, with the following keywords: nasal NO, children, allergic rhinitis, chronic rhinosinusitis, acute rhinosinusitis, primary ciliary dyskinesia (PCD), and cystic fibrosis (CF). We describe the use of nNO in pediatric allergic rhinitis, chronic rhinosinusitis, acute rhinosinusitis, PCD, and CF based on the latest literature. nNO is a noninvasive, clinically applicable test for use in pediatric allergic rhinitis, chronic rhinosinusitis, acute rhinosinusitis, PCD, and CF. It can be used as a complementary method in the diagnosis of these respiratory diseases and as a monitoring method for the treatment of allergic rhinitis and acute and chronic rhinosinusitis.

A clinical case of primary ciliary dyskinesia in a child under one year old with a pathogenic genetic variant of the DNAH5 gene described for the first time

Relevance: primary ciliary dyskinesia (PCD) is a rare hereditary autosomal recessive disease from the group of ciliopathies, which is based on a defect in the ultrastructure of the cilia of the epithelium of the respiratory tract and similar structures, leading to a violation of their motor function. It is characterized by the defeat of all parts of the respiratory tract with the formation of a chronic inflammatory process and bronchiectasis. About half of patients with PCD have a complete or incomplete reverse arrangement of internal organs with various variants of heterotaxy (situs inversus). Primary ciliary dyskinesia should be differentiated from cystic fibrosis, primary immunodeficiency conditions, congenital anomalies of the structure of the bronchial tree, bronchiectasis of other origin, bronchial asthma, congenital anomalies of the cardiovascular system. Objective: describe the clinical case of a PCD patient with the first-described pathogenic variant of the nucleotide sequence (chr5:13700862CCATAGA&gt;C) of the DNAH5 gene to familiarize doctors with the clinical features of the disease and modern diagnostic capabilities. Materials and methods: the data from the patient’s medical history, transmission electron microscopy to detect anomalies in the structure of cilia in the biopsy of the nasal mucosa and the results of molecular genetic diagnostics were used. Results. The patient was admitted for 8 months for examination and treatment in June 2022. A child from the 1st pregnancy, the first birth at 43 weeks. From anamnesis: suffered intrauterine pneumonia, otitis media without hearing loss, obstructive bronchitis, episodes of apnea. Neonatal screening for cystic fibrosis is negative. According to the PICADOR scale, 12 points were obtained. On high-speed video microscopy of cilia, there is a violation of the movements of the cilia. On computed tomography of the chest organs, the reverse location of the internal organs was noted, there were no pathological changes in the lungs. The total absence of external and internal dynein handles on transmission electron microscopy was revealed. Exome sequencing revealed the previously described variant of the nucleotide sequence in exon 68 of the DNAH5 gene (chr5:13735348G&gt; A) in a heterozygous state. Also, a previously undescribed variant of the nucleotide sequence (chr5:13700862CCATAGA&gt; C) in a heterozygous state was detected in exon 78 of the DNAH5 gene. Conclusion: modern possibilities of PCD diagnostics are demonstrated by the example of clinical observation. It is noted that patients with suspected PCD need a comprehensive examination. A pathogenic variant of the nucleotide sequence (chr5:13700862CCATAGA&gt;C) of the DNAH5 gene in a heterozygous state has been described for the first time, leading to the deletion of two amino acids without shifting the reading frame (c.13604_13609del p. (Val4535_Tyr4536del); NM_001369.3), which will help for the diagnosis of PCD in the future.

World-Renowned "Swiss" Pediatricians, Their Syndromes, and Matching Imaging Findings: A Historical Perspective.

The goal of this manuscript is to present and summarize several rare pediatric syndromes (Zellweger syndrome, Kartagener syndrome, Prader-Willi syndrome, Schinzel-Giedion syndrome, Fanconi anemia, Joubert-Boltshauser syndrome, Poretti-Boltshauser syndrome, and Langer-Giedion syndrome) who have been named after luminary "Swiss" physicians (pediatricians, pediatric neurologists, or pediatric radiologists) who recognized, studied, and published these syndromes. In this manuscript, a brief historical summary of the physicians is combined with the key clinical symptoms at presentation and the typical imaging findings. This manuscript is not aiming to give a complete comprehensive summary of the syndromes, nor does it ignore the valuable contributions of many "Swiss" scientists who are not included here, but focuses on several rare syndromes that benefit from imaging data.

Analysis of Clinical Characteristics and Gene Variants Associated with Primary Ciliary Dyskinesia

Background: Primary ciliary dyskinesia (PCD) is considered a monogenic heterogeneous recessive disorder. Objectives: This study aimed to identify clinical characteristics and gene mutations in children with PCD admitted to Quanzhou Women’s and Children’s hospital in China from January 2019 to January 2022. Methods: Clinical manifestations, lung imaging, transmission electron microscopy (TEM) findings, and genetic test results were analyzed in this study. Results: For 8 patients, PCD manifestations included asthma, total visceral inversion, secretory otitis media, adenoid hypertrophy, gastroesophageal reflux, intestinal malrotation with midgut torsion, and bronchiectasis. Primary ciliary dyskinesia-associated gene variants included DNAH11, DNAH5, RSPH4A, and CFAP300. Novel variants of DNAH11 (c.5460 + 5G &gt; C, c.117499_11752delGTTA, and c.5822G &gt; C), DNAH5 (c.4314delT and c.877dupA), RSPH4A (c.1774_1775delTT and c.1949A &gt; G), and CFAP300 (c.603delG) were found in these children. Conclusions: Recurrent cough, expectoration, purulent discharge, bronchiectasis, and visceral inversion provide clues for diagnosing early-onset PCD. Transmission electron microscopy and genetic testing improve early diagnosis, treatment delivery, and prognosis. Novel genotypes identified in this study expand the PCD genotypic spectrum.

Kartagener Syndrome Found Incidentally During Assessment of Respiratory Infection: A Case Report

Kartagener syndrome, a very rare genetic disease with autosomal recessive transmission, is described by the triad of bronchiectasis, chronic sinusitis and complete or incomplete situs inversus. This syndrome is part of primary ciliary dyskinesia, it’s characterized by clinical symptoms of respiratory infections or/and infertility. Situs inversus is often discovered incidentally. The diagnosis is confirmed by specialized centers through analysis of ciliary ultrastructure and genetic testing. Treatment is supportive and in accordance with recommendations.

Airway microbiota correlated with pulmonary exacerbation in primary ciliary dyskinesia patients.

Primary ciliary dyskinesia (PCD) is characterized by symptoms such as productive cough, rhinitis, and recurrent infections in both the upper and lower airways, which can lead to chronic infection, bronchiectasis, and decreased pulmonary function. Our study aimed to analyze the diversity and composition of the microbiota in the respiratory tract and investigate the correlation of the microbiota with pulmonary exacerbation in PCD patients. This study employed 16S rRNA amplicon sequencing to explore the microbiota present in both bronchoalveolar lavage fluid (BALF) and sputum samples collected from PCD patients. Eighty-five airway samples (17 BALF and 68 sputum samples) were collected from 72 patients aged 2 months to 60 years. Significantly lower sputum microbiota diversity and richness were found in the pulmonary exacerbation group than in the pulmonary stabilization group; additionally, the relative abundance of Pseudomonas increased when pulmonary exacerbation occurred. There was a positive correlation between pulmonary exacerbation and the relative abundance of Pseudomonas, while Streptococcus, Moraxella, and Haemophilus showed a negative correlation. Although there was no significant difference in the sputum microbiota diversity and composition in children aged 6-18 years with pulmonary exacerbation, Pseudomonas increased during pulmonary exacerbation. BALF samples of pediatric patients with pulmonary exacerbation had a lower microbiota diversity and richness; furthermore, Pseudomonas had a higher abundance and a moderate distinguishing effect. We found that microbiota beta diversity and dominance were decreased during pulmonary exacerbation. Additionally, Pseudomonas had a higher abundance and moderate distinguishing effect in pediatric patients with pulmonary exacerbation. IMPORTANCE PCD is a rare disease characterized by productive cough, rhinitis, and recurrent infections of the upper and lower airways. Because the diagnosis of PCD is often delayed, patients receive more antibiotics, experience a heavier financial burden, and have a worse prognosis; thus, it is very important to identify the pathogeny and use the correct antibiotic. In this large single-center study of PCD microbiota, we identified an outline of the bacterial microbes from the respiratory tract; furthermore, we found that the microbiota diversity in pediatric sputum was richer than that in pediatric BALF through sequencing, indicating a heterogeneous community structure. The microbiota diversity and richness were lower during pulmonary exacerbation than during pulmonary stabilization. A significantly higher abundance of Pseudomonas had a moderate distinguishing effect for lung exacerbation, which attracted more attention for the study of Pseudomonas therapy in pediatric patients with PCD.

Molecular defects in primary ciliary dyskinesia are associated with agenesis of the frontal and sphenoid paranasal sinuses and chronic rhinosinusitis.

Background: Primary ciliary dyskinesia (PCD; MIM 242650) is a rare genetic disorder characterized by malfunction of the motile cilia resulting in reduced mucociliary clearance of the airways. Together with recurring infections of the lower respiratory tract, chronic rhinosinusitis (CRS) is a hallmark symptom of PCD. Data on genotype-phenotype correlations in the upper airways are scarce. Materials and methods: We investigated the prevalence, radiologic severity, and impact on health-related quality of life (HrQoL) of CRS in 58 individuals with genetically confirmed PCD. Subgroup analysis was performed according to the predicted ultrastructural phenotype based on genetic findings. Results: Among 58 individuals harboring pathogenic variants in 22 distinct genes associated with PCD, all were diagnosed with CRS, and 47% underwent sinus surgery. A total of 36 individuals answered a German-adapted version of the 20-item Sinonasal Outcome Test (SNOT-20-GAV) with a mean score of 35.8 ± 17, indicating a remarkably reduced HrQoL. Paranasal sinus imaging of 36 individuals showed moderate-to-severe opacification with an elevated Lund-Mackay Score (LMS) of 10.2 ± 4.4. Bilateral agenesis of frontal sinus (19%) and sphenoid sinus (9.5%) was a frequent finding in individuals aged 16years or older. Subgroup analysis for predicted ultrastructural phenotypes did not identify differences in HrQoL, extent of sinus opacification, or frequency of aplastic paranasal sinuses. Conclusion: PCD is strongly associated with CRS. The high burden of disease is indicated by decreased HrQoL. Therefore, the upper airways of PCD individuals should be evaluated and managed by ear-nose-throat (ENT) specialists. Genetically determined PCD groups with predicted abnormal versus (near) normal ultrastructure did not differ in disease severity. Further studies are needed to gain evidence-based knowledge of the phenotype and management of upper airway manifestations in PCD. In addition, individuals with agenesis of the frontal and sphenoid paranasal sinuses and chronic respiratory symptoms should be considered for a diagnostic evaluation of PCD.

Otolaryngological burden of disease in children with primary ciliary dyskinesia in Victoria, Australia.

The aim of this study was to summarize the otolaryngological manifestations amongst children with primary ciliary dyskinesia (cwPCD) to improve diagnosis, investigations and management amongst otolaryngologists. A retrospective review of primary ciliary dyskinesia (PCD) diagnoses at our institution over an 8-year period between January 2014 and October 2022 was conducted. Patient characteristics, diagnosis, otolaryngological symptomatology, treatment and outcomes were recorded. 24 patients were identified. Thirteen patients (54%) had documented conductive hearing loss on audiological evaluation; with 11 (85%) requiring hearing aids. Six patients (25%) underwent middle ear ventilation tube (MEVT) insertion with 67% experiencing post-MEVT otorrhoea. Twenty children (83%) reported chronic nasal discharge however only 3 (13%) reported nasal obstruction. Nine patients (38%) had symptoms consistent with sleep disordered breathing with 79% of them requiring operative management with adenotonsillectomy. Middle ear effusion is common amongst cwPCD and should be managed with conservative measures due to the significant burden of post-MEVT otorrhoea. Sinonasal symptoms rarely need surgical intervention. Many otolaryngological symptoms of PCD are often underreported, particularly sleep-disordered breathing. Paediatric PCD patients should be managed in a multidisciplinary team with routine and tailored therapies to manage all aspects of the condition.

Which side are they on? Diagnosing primary ciliary dyskinesias in low- or middle-income countries: A review and case series.

Primary ciliary dyskinesia (PCD) is a rare genetic condition with a variable clinical presentation, making its diagnosis a challenge. We describe two unrelated sibling pairs with PCD: adult siblings in the first and perinatal/neonatal in the second. Both families highlight the more common and rarer clinical manifestations of PCD. We use these cases to highlight: (i) current understanding of the underlying genetic and pathophysiological mechanisms of PCD; (ii) the diversity of cardiac and respiratory features of PCD across a wide age range; (iii) aspects of the history and clinical examination that should raise suspicion of PCD; and (iv) the role of next-generation sequencing gene panel testing in confirmation of the diagnosis. We note genomic evidence predicting that PCD is relatively common in black African populations. What the study adds. This review of two sibling pairs illustrates the variable histories, presentations, diagnostic processes and clinical courses of primary ciliary dyskinesia (PCD) in low- or middle-income countries (LMICs), highlighting the diagnostic challenges faced when encountering such patients in settings where there may not be access to specialised resources. Possible diagnostic tools that can be used are discussed, weighing up their pros and cons in an LMIC setting, and a potential diagnostic approach that can be adapted to the treating clinician's own context is provided.Implications of the findings. Confirmation of the diagnosis of primary ciliary dyskinesia is no longer limited to well-resourced institutions, but can be done in less specialised environments using novel, highly accurate next-generation sequencing gene panel testing, reducing the need to transport patients as well as the overall cost to the healthcare system. Well-resourced institutions that see high volumes of patients with PCD can invest in new highly sensitive diagnostic tools such as high-speed video microscopy. There is a need for research investigating the validity of tools such as ciliary immunofluorescence in the South African population.

Lack of CFAP54 causes primary ciliary dyskinesia in a mouse model and human patients.

Primary ciliary dyskinesia (PCD) is a highly heterogeneous recessive inherited disorder. FAP54, the homolog of CFAP54 in Chlamydomonas reinhardtii, was previously demonstrated as the C1d projection of the central microtubule apparatus of flagella. A Cfap54 knockout mouse model was then reported to have PCD-relevant phenotypes. Through whole-exome sequencing, compound heterozygous variants c.2649_2657delinC (p. E883Dfs*47) and c.7312_7313insCGCAGGCTGAATTCTTGG (p. T2438delinsTQAEFLA) in a new suspected PCD-relevant gene, CFAP54, were identified in an individual with PCD. Two missense variants, c.4112A>C (p. E1371A) and c.6559C>T (p. P2187S), in CFAP54 were detected in another unrelated patient. In this study, a minigene assay was conducted on the frameshift mutation showing a reduction in mRNA expression. In addition, a CFAP54 in-frame variant knock-in mouse model was established, which recapitulated the typical symptoms of PCD, including hydrocephalus, infertility, and mucus accumulation in nasal sinuses. Correspondingly, two missense variants were deleterious, with a dramatic reduction in mRNA abundance from bronchial tissue and sperm. The identification of PCD-causing variants of CFAP54 in two unrelated patients with PCD for the first time provides strong supportive evidence that CFAP54 is a new PCD-causing gene. This study further helps expand the disease-associated gene spectrum and improve genetic testing for PCD diagnosis in the future.

Mutations in CFAP47, a previously reported MMAF causative gene, also contribute to the respiratory defects in patients with PCD.

Primary ciliary dyskinesia (PCD) is a genetic ciliopathy characterized by dysfunction of motile cilia. Currently, approximately 50 causative genes accounting for 60%-70% of all PCD cases have been identified in PCD-affected individuals, but the etiology in approximately 30%-40% of PCD cases remains unknown. We analyzed the clinical and genetic data of two PCD individuals who were suspected of having PCD. Whole-exome sequencing and Sanger sequencing were performed to identify and verify the variants in CFAP47. We also evaluated the expression of CFAP47 by real-time quantitative PCR and immunofluorescence. Transmission electron microscopy in respiratory epithelial cells was also conducted to analyze ciliary function. Two hemizygous missense variants of X-linked CFAP47 in two unrelated PCD individuals were identified. The expression of CFAP47 in two PCD individuals was significantly reduced in vivo and in vitro assays. A reduction in the amount of epithelial ciliary cells and basal bodies from PCD individuals was also observed. We describe two hemizygous missense variants of X-linked CFAP47 in two unrelated PCD individuals and prove CFAP47 variants are related to a reduced number of epithelial ciliary cells. Therefore, we suggest that CFAP47 should be known as a novel pathogenic gene of human PCD.

Temporal Stability of Ciliary Beating Post Nasal Brushing, Modulated by Storage Temperature.

Primary ciliary dyskinesia is a heterogeneous, inherited motile ciliopathy in which respiratory cilia beat abnormally, and some ultrastructural ciliary defects and specific genetic mutations have been associated with particular ciliary beating alterations. Ciliary beating can be evaluated using digital high-speed videomicroscopy (DHSV). However, normal reference values, essential to assess ciliary beating in patients referred for a PCD diagnostic, vary between centres, as minor variations in protocols might influence ciliary beating. Consequently, establishment of normal values is essential for each PCD diagnostic centre. We aimed to evaluate whether delay after sampling, and temperature for conservation of respiratory ciliated samples, might modify assessments of ciliary beating. In total, 37 healthy nasal brushing samples of respiratory ciliated epithelia were collected. Video sequences were recorded at 37 °C immediately using DHSV. Then, the samples were divided and conserved at 4 °C or at room temperature (RT). Ciliated beating edges were then recorded at 37 °C, at 3 h and at 9 h post sampling. In six samples, recordings were continued up to 72 h after sampling. Ciliary beating was assessed manually by ciliary beat frequency (CBFM) and ciliary beat pattern (CBP). A semi-automatic software was used for quantitative analysis. Both CBF and CBP evaluated manually and by a semi-automated method were stable 9 h after sampling. CBFM was higher when evaluated using samples stored at RT than at 4 °C. CBP and the semi-automated evaluation of ciliary beating were not affected by storage temperature. When establishing normal references values, ciliary beating can be evaluated at 37 °C up to 9 h after nasal brushing, but the storage temperature modifies ciliary beating and needs to be controlled.

Impaired Nitric Oxide Synthetase Activity in Primary Ciliary Dyskinesia-Data-Driven Hypothesis.

Low nasal nitric oxide (nNO) is a typical feature of Primary Ciliary Dyskinesia (PCD). nNO is part of the PCD diagnostic algorithm due to its discriminative power against other lung diseases, such as cystic fibrosis (CF). However, the underlying pathomechanisms are elusive. To better understand NO dysregulation in PCD, the L-arginine/NO (Arg/NO) pathway in patients with PCD (pwPCD) and CF (pwCF) and in healthy control (HC) subjects was investigated. In a prospective, controlled study, we measured in 24 pwPCD, 25 age-matched pwCF, and 14 HC the concentrations of the NO precursors Arg and homoarginine (hArg), the arginase metabolite ornithine (Orn), the NO inhibitor asymmetric dimethylarginine (ADMA), and the major NO metabolites (nitrate, nitrite) in sputum, plasma, and urine using validated methods. In comparison to HC, the sputum contents (in µmol/mg) of L-Arg (PCD 18.43 vs. CF 329.46 vs. HC 9.86, p < 0.001) and of ADMA (PCD 0.055 vs. CF 0.015 vs. HC 0.010, p < 0.001) were higher. In contrast, the sputum contents (in µmol/mg) of nitrate and nitrite were lower in PCD compared to HC (nitrite 4.54 vs. 9.26, p = 0.023; nitrate 12.86 vs. 40.33, p = 0.008), but higher in CF (nitrite 16.28, p < 0.001; nitrate 56.83, p = 0.002). The metabolite concentrations in urine and plasma were similar in all groups. The results of our study indicate that PCD, unlike CF, is associated with impaired NO synthesis in the lung, presumably due to mechano-chemical uncoupling.

Inherently disordered regions of axonemal dynein assembly factors.

The dynein-driven beating of cilia is required to move individual cells and to generate fluid flow across surfaces and within cavities. These motor enzymes are highly complex and can contain upwards of 20 different protein components with a total mass approaching 2 MDa. The dynein heavy chains are enormous proteins consisting of ~4500 residues and ribosomes take approximately 15 min to synthesize one. Studies in a broad array of organisms ranging from the green alga Chlamydomonas to humans has identified 19 cytosolic factors (DNAAFs) that are needed to specifically build axonemal dyneins; defects in many of these proteins lead to primary ciliary dyskinesia in mammals which can result in infertility, severe bronchial problems, and situs inversus. How all these factors cooperate in a spatially and temporally regulated manner to promote dynein assembly in cytoplasm remains very uncertain. These DNAAFs contain a variety of well-folded domains many of which provide protein interaction surfaces. However, many also exhibit large regions that are predicted to be inherently disordered. Here I discuss the nature of these unstructured segments, their predicted propensity for driving protein phase separation, and their potential for adopting more defined conformations during the dynein assembly process.