Clinical and Genetic Spectrum of Children with Primary Ciliary Dyskinesia in China

Prenatal genetic diagnosis of fetuses with dextrocardia using whole exome sequencing in a tertiary center

To evaluate the genetic etiology of fetal dextrocardia, associated ultrasound anomalies, and perinatal outcomes, we investigated the utility of whole exome sequencing (WES) for prenatal diagnosis of dextrocardia. Fetuses with dextrocardia were prospectively collected between January 2016 and December 2022. Trio-WES was performed on fetuses with dextrocardia, following normal karyotyping and/or chromosomal microarray analysis (CMA) results. A total of 29 fetuses with dextrocardia were collected, including 27 (93.1%) diagnosed with situs inversus totalis and 2 (6.9%) with situs inversus partialis. Cardiac malformations were present in nine cases, extra-cardiac anomalies were found in seven cases, and both cardiac and extra-cardiac malformations were identified in one case. The fetal karyotypes and CMA results of 29 cases were normal. Of the 29 cases with dextrocardia, 15 underwent WES, and the other 14 cases refused. Of the 15 cases that underwent WES, clinically relevant variants were identified in 5/15 (33.3%) cases, including the diagnostic variants DNAH5, DNAH11, LRRC56, PEX10, and ZIC3, which were verified by Sanger sequencing. Of the 10 cases with non-diagnostic results via WES, eight (80%) chose to continue the pregnancies. Of the 29 fetuses with dextrocardia, 10 were terminated during pregnancy, and 19 were live born. Fetal dextrocardia is often accompanied by cardiac and extra-cardiac anomalies, and fetal dextrocardia accompanied by situs inversus is associated with a high risk of primary ciliary dyskinesia. Trio-WES is recommended following normal karyotyping and CMA results because it can improve the diagnostic utility of genetic variants of fetal dextrocardia, accurately predict fetal prognosis, and guide perinatal management and the reproductive decisions of affected families.

Two Japanese Pediatric Patients With Primary Ciliary Dyskinesia Caused by Loss-of-Function Variants in the CCNO gene

Primary ciliary dyskinesia (PCD) is a rare congenital disorder caused by pathogenic variants of genes related to cilia. Here, we report two Japanese pediatric patients with PCD caused by pathogenic compound heterozygous variants in the cyclin O (CCNO) gene (Case 1, NM_021147.4:c.[262C>T];[781delC], p.[Gln88Ter];[Leu261fs]; Case 2, c.[262C>T];[c.248_252dupTGCCC], p.[Gln88Ter];[Gly85fs]). The clinical symptoms of the patients were varied. Neither of the patients had situs inversus. Transmission electron microscopy of the respiratory cilia from the nasal mucosa in Case 1 showed a remarkable reduction of cilia and the few residual cilia had central pair defects and microtubular disorganization.

Next-Generation Sequencing-Based Copy Number Variation Analysis in Chinese Patients with Primary Ciliary Dyskinesia Revealed Novel DNAH5 Copy Number Variations

Primary ciliary dyskinesia (PCD) is a rare disorder characterized by extensive genetic heterogeneity. However, in the genetic pathogenesis of PCD, copy number variation (CNV) has not received sufficient attention and has rarely been reported, especially in China. Next-generation sequencing (NGS) followed by targeted CNV analysis was used in patients highly suspected to have PCD with negative results in routine whole-exome sequencing (WES) analysis. Quantitative real-time polymerase chain reaction (qPCR) and Sanger sequencing were used to confirm these CNVs. To further characterize the ciliary phenotypes, high-speed video microscopy analysis (HSVA), transmission electron microscopy (TEM), and immunofluorescence (IF) analysis were used. Patient 1 (F1: II-1), a 0.6-year-old girl, came from a nonconsanguineous family-I. She presented with situs inversus totalis, neonatal respiratory distress, and sinusitis. The nasal nitric oxide level was markedly reduced. The respiratory cilia beat with reduced amplitude. TEM revealed shortened outer dynein arms (ODA) of cilia. chr5:13717907-13722661del spanning exons 71-72 was identified by NGS-based CNV analysis. Patient 2 (F2: IV-4), a 37-year-old man, and his eldest brother Patient 3 (F2: IV-2) came from a consanguineous family-II. Both had sinusitis, bronchiectasis and situs inversus totalis. The respiratory cilia of Patient 2 and Patient 3 were found to be uniformly immotile, with ODA defects. Two novel homozygous deletions chr5:13720087_13733030delinsGTTTTC and chr5:13649539_1 3707643del, spanning exons 69-71 and exons 77-79 were identified by NGS-based CNV analysis. Abnormalities in DNA copy number were confirmed by qPCR amplification. IF showed that the respiratory cilia of Patient 1 and Patient 2 were deficient in dynein axonemal heavy chain 5 (DNAH5) protein expression. This report identified three novel DNAH5 disease-associated variants by WES-based CNV analysis. Our study expands the genetic spectrum of PCD with DNAH5 in the Chinese population.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-023-00130-0.

Clinical implications of respiratory ciliary dysfunction in heterotaxy patients with congenital heart disease: elevated risk of postoperative airway complications

Objective

Cardiac surgery in Congenital Heart Disease-Heterotaxy (CHD-HTX) patients often leads to increased postoperative airway complications. Abnormal respiratory ciliary function, resembling primary ciliary dyskinesia, has been observed. We expanded the sample size by retrospectively reviewing Ciliary Dysfunction (CD) in CHD-HTX patients to verify the increased risk of post-surgical respiratory complications.

Methods

We conducted a retrospective review of 69 CHD-HTX patients undergoing cardiac surgery, assessing abnormal respiratory function using nasal nitric oxide (nNO) levels and nasal ciliary motion observed in video microscopy. Data collected included demographics, surgical details, postoperative complications, length of stay, ICU hours, salvage procedures, intubation duration, and mortality.

Results

The CD and no-CD cohorts exhibited notable similarities in risk adjustment in Congenital Heart Surgery-1 (RACHS-1) risk categories, age at the time of surgery, and the duration of follow-up evaluations. We observed a trend toward an increased length of post-operative stay in the CD group (15.0 vs. 14.0; P = 0.0017). CHD-HTX patients with CD showed significantly higher rates of respiratory complications (70% vs. 44.4%; P = 0.008). There were no notable variances observed in postoperative hospitalization duration, mechanical ventilation period, or surgical mortality.

Conclusion

Our findings suggest that CHD-HTX patients with CD may face an elevated risk of respiratory complications. These results offer guidance for perioperative management and serve as a reference for further pathological studies.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Airway microbiota correlated with pulmonary exacerbation in primary ciliary dyskinesia patients

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.

NGS study in a sicilian case series with a genetic diagnosis for Gerstmann-Sträussler-Scheinker syndrome (PRNP, p.P102L)

BACKGROUND

Gerstmann Sträussler Scheinker (GSS) is an inherited, invariably fatal prion disease. Like other human prion diseases, GSS is caused by missense mutations in the prion protein (PrP) gene (PRNP), and by the formation and overtime accumulation of the misfolded, pathogenic scrapie PrP (PrPSc). The first mutation identified in the PRNP gene, and the one blamed as the main cause of the disease, is c.C305T:p.P102L.

METHODS AND RESULTS

The Sanger sequencing method was performed on the PRNP gene for the detection of c.C305T:p.P102L mutations in a cohort of 10 subjects; moreover, a study was carried out, using Next Generation Sequencing (NGS), by sequencing a group of genes related to amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), movement disorders and dementia which show a phenotypic profile similar to that of GSS. The results obtained from the study using NGS indicate the potential role of other genetic variants which could contribute to the various GSS phenotypes.

CONCLUSIONS

In conclusion, we highlight the large clinical variability in subjects presenting with GSS and p.P102L, as well as the hypothesis that the mutation in PrP codon 102 alone is not sufficient to trigger the cardinal clinical signs of the disease; furthermore, we do not exclude the possibility that further genetic variants play a decisive role in the aspects of the various phenotypes with which GSS manifests itself.

ODAD1 variants resulting from splice-site mutations retain partial function and cause primary ciliary dyskinesia with outer dynein arm defects

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder caused by defects in motile ciliary function and/or structure. Outer dynein arm docking complex subunit 1 (ODAD1) is an important component of the outer dynein arm docking complex (ODA-DC). To date, 13 likely pathogenic mutations of ODAD1 have been reported. However, the pathogenesis of ODAD1 mutations remains elusive. To investigate the pathogenesis of splice-site mutations in ODAD1 discovered in this study and those reported previously, molecular and functional analyses were performed. Whole-exome sequencing revealed a compound mutation in ODAD1 (c.71-2A>C; c.598-2A>C) in a patient with PCD, with c.598-2A>C being a novel mutation that resulted in two mutant transcripts. The compound mutation in ODAD1 (c.71-2A>C; c.598-2A>C) led to aberrant splicing that resulted in the absence of the wild-type ODAD1 and defects of the outer dynein arm in ciliary axonemes, causing a decrease in ciliary beat frequency. Furthermore, we demonstrated that the truncated proteins resulting from splice-site mutations in ODAD1 could retain partial function and inhibit the interaction between wild-type ODAD1 and ODAD3. The results of this study expand the mutational and clinical spectrum of PCD, provide more evidence for genetic counseling, and offer new insights into gene-based therapeutic strategies for PCD.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Regulatory network and targeted interventions for CCDC family in tumor pathogenesis

CCDC (coiled-coil domain-containing) is a coiled helix domain that exists in natural proteins. There are about 180 CCDC family genes, encoding proteins that are involved in intercellular transmembrane signal transduction and genetic signal transcription, among other functions. Alterations in expression, mutation, and DNA promoter methylation of CCDC family genes have been shown to be associated with the pathogenesis of many diseases, including primary ciliary dyskinesia, infertility, and tumors. In recent studies, CCDC family genes have been found to be involved in regulation of growth, invasion, metastasis, chemosensitivity, and other biological behaviors of malignant tumor cells in various cancer types, including nasopharyngeal carcinoma, lung cancer, colorectal cancer, and thyroid cancer. In this review, we summarize the involvement of CCDC family genes in tumor pathogenesis and the relevant upstream and downstream molecular mechanisms. In addition, we summarize the potential of CCDC family genes as tumor therapy targets. The findings discussed here help us to further understand the role and the therapeutic applications of CCDC family genes in tumors.

Bronchial gene expression alterations associated with radiological bronchiectasis

OBJECTIVES

Discovering airway gene expression alterations associated with radiological bronchiectasis may improve the understanding of the pathobiology of early-stage bronchiectasis.

METHODS

Presence of radiological bronchiectasis in 173 individuals without a clinical diagnosis of bronchiectasis was evaluated. Bronchial brushings from these individuals were transcriptomically profiled and analysed. Single-cell deconvolution was performed to estimate changes in cellular landscape that may be associated with early disease progression.

RESULTS

20 participants have widespread radiological bronchiectasis (three or more lobes). Transcriptomic analysis reflects biological processes associated with bronchiectasis including decreased expression of genes involved in cell adhesion and increased expression of genes involved in inflammatory pathways (655 genes, false discovery rate <0.1, log2 fold-change >0.25). Deconvolution analysis suggests that radiological bronchiectasis is associated with an increased proportion of ciliated and deuterosomal cells, and a decreased proportion of basal cells. Gene expression patterns separated participants into three clusters: normal, intermediate and bronchiectatic. The bronchiectatic cluster was enriched by participants with more lobes of radiological bronchiectasis (p<0.0001), more symptoms (p=0.002), higher SERPINA1 mutation rates (p=0.03) and higher computed tomography derived bronchiectasis scores (p<0.0001).

CONCLUSIONS

Genes involved in cell adhesion, Wnt signalling, ciliogenesis and interferon-γ pathways had altered expression in the bronchus of participants with widespread radiological bronchiectasis, possibly associated with decreased basal and increased ciliated cells. This gene expression pattern is not only highly enriched among individuals with radiological bronchiectasis, but also associated with airway-related symptoms in those without discernible radiological bronchiectasis, suggesting that it reflects a bronchiectasis-associated, but non-bronchiectasis-specific lung pathophysiological process.

CLPP Depletion Causes Diplotene Arrest; Underlying Testis Mitochondrial Dysfunction Occurs with Accumulation of Perrault Proteins ERAL1, PEO1, and HARS2

Human Perrault syndrome (PRLTS) is autosomal, recessively inherited, and characterized by ovarian insufficiency with hearing loss. Among the genetic causes are mutations of matrix peptidase CLPP, which trigger additional azoospermia. Here, we analyzed the impact of CLPP deficiency on male mouse meiosis stages. Histology, immunocytology, different OMICS and biochemical approaches, and RT-qPCR were employed in CLPP-null mouse testis. Meiotic chromosome pairing and synapsis proceeded normally. However, the foci number of the crossover marker MLH1 was slightly reduced, and foci persisted in diplotene, most likely due to premature desynapsis, associated with an accumulation of the DNA damage marker γH2AX. No meiotic M-phase cells were detected. Proteome profiles identified strong deficits of proteins involved in male meiotic prophase (HSPA2, SHCBP1L, DMRT7, and HSF5), versus an accumulation of AURKAIP1. Histone H3 cleavage, mtDNA extrusion, and cGAMP increase suggested innate immunity activation. However, the deletion of downstream STING/IFNAR failed to alleviate pathology. As markers of underlying mitochondrial pathology, we observed an accumulation of PRLTS proteins ERAL1, PEO1, and HARS2. We propose that the loss of CLPP leads to the extrusion of mitochondrial nucleotide-binding proteins to cytosol and nucleus, affecting late meiotic prophase progression, and causing cell death prior to M-phase entry. This phenotype is more severe than in mito-mice or mutator-mice.

Multiomics Analysis of a DNAH5-Mutated PCD Organoid Model Revealed the Key Role of the TGF-β/BMP and Notch Pathways in Epithelial Differentiation and the Immune Response in DNAH5-Mutated Patients

Dynein axonemal heavy chain 5 (DNAH5) is the most mutated gene in primary ciliary dyskinesia (PCD), leading to abnormal cilia ultrastructure and function. Few studies have revealed the genetic characteristics and pathogenetic mechanisms of PCD caused by DNAH5 mutation. Here, we established a child PCD airway organoid directly from the bronchoscopic biopsy of a patient with the DNAH5 mutation. The motile cilia in the organoid were observed and could be stably maintained for an extended time. We further found abnormal ciliary function and a decreased immune response caused by the DNAH5 mutation through single-cell RNA sequencing (scRNA-Seq) and proteomic analyses. Additionally, the directed induction of the ciliated cells, regulated by TGF-β/BMP and the Notch pathway, also increased the expression of inflammatory cytokines. Taken together, these results demonstrated that the combination of multiomics analysis and organoid modelling could reveal the close connection between the immune response and the DNAH5 gene.

Uncovering the burden of hidden ciliopathies in the 100 000 Genomes Project: a reverse phenotyping approach

BACKGROUND

The 100 000 Genomes Project (100K) recruited National Health Service patients with eligible rare diseases and cancer between 2016 and 2018. PanelApp virtual gene panels were applied to whole genome sequencing data according to Human Phenotyping Ontology (HPO) terms entered by recruiting clinicians to guide focused analysis.

METHODS

We developed a reverse phenotyping strategy to identify 100K participants with pathogenic variants in nine prioritised disease genes (BBS1, BBS10, ALMS1, OFD1, DYNC2H1, WDR34, NPHP1, TMEM67, CEP290), representative of the full phenotypic spectrum of multisystemic primary ciliopathies. We mapped genotype data 'backwards' onto available clinical data to assess potential matches against phenotypes. Participants with novel molecular diagnoses and key clinical features compatible with the identified disease gene were reported to recruiting clinicians.

RESULTS

We identified 62 reportable molecular diagnoses with variants in these nine ciliopathy genes. Forty-four have been reported by 100K, 5 were previously unreported and 13 are new diagnoses. We identified 11 participants with unreportable, novel molecular diagnoses, who lacked key clinical features to justify reporting to recruiting clinicians. Two participants had likely pathogenic structural variants and one a deep intronic predicted splice variant. These variants would not be prioritised for review by standard 100K diagnostic pipelines.

CONCLUSION

Reverse phenotyping improves the rate of successful molecular diagnosis for unsolved 100K participants with primary ciliopathies. Previous analyses likely missed these diagnoses because incomplete HPO term entry led to incorrect gene panel choice, meaning that pathogenic variants were not prioritised. Better phenotyping data are therefore essential for accurate variant interpretation and improved patient benefit.

Clinical and genetic spectrum of primary ciliary dyskinesia in Chinese patients: a systematic review

Background

Primary ciliary dyskinesia (PCD) represents a highly heterogenous disorder with extensive clinical and genetic patterns among populations of different geographic location and ethnic origin. However, data about Chinese patients are limited. We aimed to summarize the clinical and genetic spectrum of Chinese PCD patients based on all available literatures.

Methods

We searched Embase, Pubmed, Web of Science and Chinese databases including CNKI, SinoMed and Wanfang from 1981 to 2021, to identify articles reporting patients with PCD in China, which had included information about transmission electron microscopy and/or genetic testing.

Results

A total of 244 Chinese PCD patients in 52 articles were included. Of these patients, the mean age was 13.1 years, and 55 patients (22.5%) were diagnosed with PCD after 18 years old. Compared with patients diagnosed with PCD in childhood or infancy, patients diagnosed with PCD in adulthood had a higher prevalence of chronic wet cough, sinusitis, Pseudomonas aeruginosa (PA) isolation and radiological bronchiectasis as well as worse lung function. 25 PCD-related genes were identified in 142 patients, and DNAH5, DNAH11, CCDC39 and CCDC40 were the most frequently detected mutations. More than half of genetic variants were loss-of-function mutations, and the majority of these variants were seen only once. Correlations between PCD phenotype, genotype and ciliary ultrastructure were also evidenced.

Conclusions

Diagnostic delay and under-recognition of PCD remain a big issue in China, which contributes to progressive lung disease and PA infection indicating worse outcome. Specialist equipment and expertise are urgently required to facilitate the early diagnosis and treatment of PCD.

Trial registry

PROSPERO; No.: CRD42021257804; URL:www.crd.york.ac.uk/prospero/

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02427-1.

Clinical and genetic features of primary ciliary dyskinesia in a cohort of consecutive clinically suspect children in western China

BACKGROUND

Primary ciliary dyskinesia (PCD) is a rare, inherited disorder of the motile cilia that exhibits genetic and clinical heterogeneity among different populations. PCD diagnosis remains challenging owing to the heterogeneity of associated clinical features and lack of a gold standard diagnostic test.

OBJECTIVE

The aim of this study was to analyze the clinical and genetic characteristics of a group of children with clinically suspected PCD in one region of China, with the goal of providing a more robust knowledge base regarding the genetic stratification underlying this disease in Chinese populations.

METHODS

We retrospectively analyzed the data from 38 patients with clinically suspected PCD who had undergone next-generation sequencing (NGS) between November 2016 and March 2021 in the respiratory department of a tertiary Children's hospital in Western China. The genetic features of the confirmed cases were summarized by reviewing data associated with other cohorts of Chinese children.

RESULTS

Overall, 16 patients were ultimately diagnosed with PCD with a median age of 8.5 years. All patients presented with a chronic wet cough, 93.75% exhibited chronic or recurrent sinusitis/rhinitis, 43.75% experienced recurrent wheezing, 56.25% reported respiratory symptoms present since infancy, 31.25% had a history of neonatal respiratory distress (NRD), and 25% exhibited otitis media. Only 18.75% of these patients exhibited laterality defects. High frequencies of DNAH11 mutations were detected by integrating data from PCD patient cohorts in China.

CONCLUSION

The high frequency of DNAH11 mutations may limit the utility of transmission electron microscopy (TEM) as a first-line approach to diagnosing PCD in China in the absence of other indicators.

Identification of a Novel OFD1 Variant in a Patient with Primary Ciliary Dyskinesia

Background

OFD1 encodes a protein with 1012 amino acids, which is a component of basal bodies and centrioles, essential for cilia biogenesis. OFD1 was reported to be associated with X-chromosome linked dysmorphology syndrome in early studies and recent studies reported a few cases with primary ciliary dyskinesia (PCD) caused by OFD1 deficiency.

Case Presentation

We report a 31-year-old man who suffered from recurrent respiratory infections with typical manifestations of primary ciliary dyskinesia. In addition to respiratory manifestations, the patient also had situs inversus, obesity, gastroesophageal reflux, and hearing impairment. Clubbing fingers and mild streblomicrodactyly were also observed.

Examination Result

We performed whole-exome sequencing to identify a novel variant c.2795delA:p.(Lys932Argfs*3) in OFD1. The hemizygous variant was predicted to be likely pathogenic by bioinformatic analysis software and ACMG guideline. High-speed video microscopy (HSVM), transmission electron microscopy (TEM), and immunofluorescence were performed to analyze the respiratory cilia. A high beating frequency and a stiff beating pattern were observed under HSVM, while there were no significant abnormalities in TEM and immunofluorescence. The sperm flagella examinations were also generally normal.

Conclusion

Our study identified a novel frameshift variant in OFD1 causing PCD, enriched the genetic spectrum of OFD1 variants, and verified that OFD1 mutation can lead to only a PCD characteristic phenotype, while other OFD1-associated syndromic symptoms such as dysmorphic features and renal symptoms were not present.

Reducing exacerbations in children and adults with primary ciliary dyskinesia using erdosteine and/or azithromycin therapy (REPEAT trial): study protocol for a multicentre, double-blind, double-dummy, 2×2 partial factorial, randomised controlled trial

Introduction

Primary ciliary dyskinesia (PCD) is a rare, progressive, inherited ciliopathic disorder, which is incurable and frequently complicated by the development of bronchiectasis. There are few randomised controlled trials (RCTs) involving children and adults with PCD and thus evidence of efficacy for interventions are usually extrapolated from people with cystic fibrosis. Our planned RCT seeks to address some of these unmet needs by employing a currently prescribed (but unapproved for long-term use in PCD) macrolide antibiotic (azithromycin) and a novel mucolytic agent (erdosteine). The primary aim of our RCT is to determine whether regular oral azithromycin and erdosteine over a 12-month period reduces acute respiratory exacerbations among children and adults with PCD. Our primary hypothesis is that: people with PCD who regularly use oral azithromycin and/or erdosteine will have fewer exacerbations than those receiving the corresponding placebo medications. Our secondary aims are to determine the effect of the trial medications on PCD-specific quality-of-life (QoL) and other clinical outcomes (lung function, time-to-next exacerbation, hospitalisations) and nasopharyngeal bacterial carriage and antimicrobial resistance.

Methods and analysis

We are currently undertaking a multicentre, double-blind, double-dummy RCT to evaluate whether 12 months of azithromycin and/or erdosteine is beneficial for children and adults with PCD. We plan to recruit 104 children and adults with PCD to a parallel, 2×2 partial factorial superiority RCT at five sites across Australia. Our primary endpoint is the rate of exacerbations over 12 months. Our main secondary outcomes are QoL, lung function and nasopharyngeal carriage by respiratory bacterial pathogens and their associated azithromycin resistance.

Ethics and dissemination

Our RCT is conducted in accordance with Good Clinical Practice and the Australian legislation and National Health and Medical Research Council guidelines for ethical conduct of Research, including that for First Nations Australians.

Trial registration number

ACTRN12619000564156.

Novel Compound Heterozygous Variants in CCDC40 Associated with Primary Ciliary Dyskinesia and Multiple Morphological Abnormalities of the Sperm Flagella

Primary ciliary dyskinesia (PCD) is a rare genetic disease caused by mutations of genes coding motile-cilia-related proteins. CCDC40 variants can cause PCD via disrupting the assembling of inner dynein and dynein regulating complex in cilia and flagella, but none has been reported associated with multiple morphological abnormalities of the sperm flagella (MMAF). We identified and validated the disease-causing variants in our patient via whole-exome and Sanger sequencing. We used high-speed video microscopy analysis (HSVA) and immunofluorescence to analyze the functional and structural deficiency of respiratory cilia. Papanicolaou staining and scanning electron microscope was applied to analyze the morphological sperm defects resulted from the PCD associated variants. We identified novel compound variants (c.901C>T, p.(Arg301*); c.2065_2068dup, p.(Ala690Glyfs*67)) in CCDC40 in a male patient with male infertility. HSVA revealed the rigid and stiff ciliary beating pattern. Immunofluorescence indicated loss of inner dynein arm protein DNAH2 both in cilia and the sperms of the patient. Diagnosis of MMAF was confirmed through sperm Papanicolaou staining and scanning electron microscope. We first describe a patient with a combination of PCD and MMAF associated with novel compound heterozygous variants in CCDC40. Our results present initial evidence that CCDC40 associated with MMAF, which expands the genetic spectrum of PCD and MMAF and provides precise clinical genetic counseling to this family.

Pediatric pulmonology 2020 year in review: Rare and diffuse lung disease

Pediatric Pulmonology publishes original research, review articles, and case reports on topics related to a wide range of children's respiratory disorders. Here we review some of the most notable manuscripts published in 2020 in this journal on (1) children's interstitial lung disease (chILD), (2) congenital airway and lung anomalies, and (3) primary ciliary dyskinesia and other non-cystic fibrosis bronchiectasis. The articles reviewed are discussed in context with published works from other journals.

A Novel Compound Heterozygous Mutation in the DNAH11 Gene Found in Neonatal Twins With Primary Ciliary Dyskinesis

Background: Primary ciliary dyskinesia (PCD) is a rare genetically heterogeneous disorder of motile cilia. Common features of PCD include upper and lower respiratory tract disease, secretory otitis media, situs inversus and fertility problems. To date, although several PCD-associated genes have been identified, the genetic causes of most PCD cases remain elusive.

Methods: In this case study, we analyzed the clinical and genetic data of one case of monochorionic diamniotic twins which were suspected of having PCD on the basis of clinical and radiological features including situs inversus, recurrent wet cough and sinusitis as well as varying degrees of respiratory distress. Whole-exome sequencing was performed to identify variants of the DNAH11 gene in the twins. Sanger sequencing and real-time quantitative polymerase chain reaction (RT-qPCR) were used for validation of DNAH11 variants both in the patient and the twins.

Results: In the twins, we found a novel mutation at c.2436C > G (p.Y812 *) and a pathogenic deletion encompassing 2.0 Kb of 7P15.3 ([GRCh38] chr7: g.21,816,397-21,818,402). The deleted region included exons 64 and 65 of DNAH11. Sanger sequencing also revealed that the twins’ father was a carrier of heterozygous C.2436C > G and a heterozygous deletion was detected in the mother. No other clinically relevant genetic variants were identified.

Conclusion: We describe a novel DNAH11 gene compound heterozygous mutation in newborn twins with PCD and recommend that PCD diagnosis should be considered in newborns presenting with respiratory distress and/or situs inversus. Early diagnosis and treatment of PCD will help control disease progression and improve the patient’s quality of life.

LncRNA functional annotation with improved false discovery rate achieved by disease associations

The long non‐coding RNAs (lncRNAs) play critical roles in various biological processes and are associated with many diseases. Functional annotation of lncRNAs in diseases attracts great attention in understanding their etiology. However, the traditional co-expression-based analysis usually produces a significant number of false positive function assignments. It is thus crucial to develop a new approach to obtain lower false discovery rate for functional annotation of lncRNAs. Here, a novel strategy termed DAnet which combining disease associations with cis-regulatory network between lncRNAs and neighboring protein-coding genes was developed, and the performance of DAnet was systematically compared with that of the traditional differential expression-based approach. Based on a gold standard analysis of the experimentally validated lncRNAs, the proposed strategy was found to perform better in identifying the experimentally validated lncRNAs compared with the other method. Moreover, the majority of biological pathways (40%∼100%) identified by DAnet were reported to be associated with the studied diseases. In sum, the DAnet is expected to be used to identify the function of specific lncRNAs in a particular disease or multiple diseases.

Impact of Motile Ciliopathies on Human Development and Clinical Consequences in the Newborn

Motile cilia are hairlike organelles that project outward from a tissue-restricted subset of cells to direct fluid flow. During human development motile cilia guide determination of the left-right axis in the embryo, and in the fetal and neonatal periods they have essential roles in airway clearance in the respiratory tract and regulating cerebral spinal fluid flow in the brain. Dysregulation of motile cilia is best understood through the lens of the genetic disorder primary ciliary dyskinesia (PCD). PCD encompasses all genetic motile ciliopathies resulting from over 60 known genetic mutations and has a unique but often underrecognized neonatal presentation. Neonatal respiratory distress is now known to occur in the majority of patients with PCD, laterality defects are common, and very rarely brain ventricle enlargement occurs. The developmental function of motile cilia and the effect and pathophysiology of motile ciliopathies are incompletely understood in humans. In this review, we will examine the current understanding of the role of motile cilia in human development and clinical considerations when assessing the newborn for suspected motile ciliopathies.

Mutations in Hsp90 Cochaperones Result in a Wide Variety of Human Disorders

The Hsp90 molecular chaperone, along with a set of approximately 50 cochaperones, mediates the folding and activation of hundreds of cellular proteins in an ATP-dependent cycle. Cochaperones differ in how they interact with Hsp90 and their ability to modulate ATPase activity of Hsp90. Cochaperones often compete for the same binding site on Hsp90, and changes in levels of cochaperone expression that occur during neurodegeneration, cancer, or aging may result in altered Hsp90-cochaperone complexes and client activity. This review summarizes information about loss-of-function mutations of individual cochaperones and discusses the overall association of cochaperone alterations with a broad range of diseases. Cochaperone mutations result in ciliary or muscle defects, neurological development or degeneration disorders, and other disorders. In many cases, diseases were linked to defects in established cochaperone-client interactions. A better understanding of the functional consequences of defective cochaperones will provide new insights into their functions and may lead to specialized approaches to modulate Hsp90 functions and treat some of these human disorders.

OFD Type I syndrome: lessons learned from a rare ciliopathy

The OFD1 gene was initially identified as the gene responsible for the X-linked dominant male lethal OFD type I syndrome, a developmental disorder ascribed to cilia disfunction. The transcript has been subsequently associated to four different X-linked recessive conditions, namely Joubert syndrome, retinitis pigmentosa, primary ciliary dyskinesia and Simpson-Golabi-Behmel type 2 syndrome. The centrosomal/basal body OFD1 protein has indeed been shown to be required for primary cilia formation and left-right asymmetry. The protein is also involved in other tasks, e.g. regulation of cellular protein content, constrain of the centriolar length, chromatin remodeling at DNA double strand breaks, control of protein quality balance and cell cycle progression, which might be mediated by non-ciliary activities. OFD1 represents a paradigmatic model of a protein that performs its diverse actions according to the cell needs and depending on the subcellular localization, the cell type/tissue and other possible factors still to be determined. An increased number of multitask protein, such as OFD1, may represent a partial explanation to human complexity, as compared with less complex organisms with an equal or slightly lower number of proteins.

Case Report: Novel Biallelic Mutations in ARMC4 Cause Primary Ciliary Dyskinesia and Male Infertility in a Chinese Family

Primary ciliary dyskinesia (PCD) is a clinically and genetically heterogeneous ciliopathy affecting the cilia and sperm flagella. Mutations in genes related to the structural and functional defects of respiratory ciliary axoneme have been reported to be the predominant cause of this symptom; however, evidence regarding male infertility and genotype–phenotype associations between some of these genes and flagellar axoneme remains unclear. Here, we reported a male patient from a non-consanguineous Chinese family who exhibited left/right body asymmetry and oligoasthenoterazoospermia factor infertility. Novel compound heterozygous mutations in ARMC4 (NM:018076: c.2095C>T: p. Gln699^*; c.1679C>T: p. Ala560Val) were identified in this patient, and his parents were a heterozygous carrier for the mutations. Morphological and ultrastructural analysis of the spermatozoa from the man showed aberrant sperm flagella with axonemal disorganization and outer dynein arm (ODA) loss. In addition, immunofluorescence analysis of the spermatozoa from the proband and a control man revealed a significant lower expression of ARMC4 protein due to pathogenic mutations. Therefore, our findings help to expand the spectrum of ARMC4 pathogenic mutations and linked biallelic ARMC4 mutations to male infertility for the first time.

Clinical characteristics and genetic spectrum of 26 individuals of Chinese origin with primary ciliary dyskinesia

Background

Primary ciliary dyskinesia (PCD) is a rare, highly heterogeneous genetic disorder involving the impairment of motile cilia. With no single gold standard for PCD diagnosis and complicated multiorgan dysfunction, the diagnosis of PCD can be difficult in clinical settings. Some methods for diagnosis, such as nasal nitric oxide measurement and digital high-speed video microscopy with ciliary beat pattern analysis, can be expensive or unavailable. To confirm PCD diagnosis, we used a strategy combining assessment of typical symptoms with whole-exome sequencing (WES) and/or low-pass whole-genome sequencing (WGS) as an unbiased detection tool to identify known pathogenic mutations, novel variations, and copy number variations.

Results

A total of 26 individuals of Chinese origin with a confirmed PCD diagnosis aged 13 to 61 years (median age, 24.5 years) were included. Biallelic pathogenic mutations were identified in 19 of the 26 patients, including 8 recorded HGMD mutations and 24 novel mutations. The detection rate reached 73.1%. DNAH5 was the most frequently mutated gene, and c.8383C > T was the most common mutated variant, but it is relatively rare in PCD patients from other ethnic groups.

Conclusion

This study demonstrates the practical clinical utility of combining WES and low-pass WGS as a no-bias detecting tool in adult patients with PCD, showing a clinical characteristics and genetic spectrum of Chinese PCD patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01840-2.

DNAH11 compound heterozygous variants cause heterotaxy and congenital heart disease

Heterotaxy (HTX), a condition characterized by internal organs not being arranged as expected relative to each other and to the left-right axis, is often accompanied with congenital heart disease (CHD). The purpose was to detect the pathogenic variants in a Chinese family with HTX and CHD. A non-consanguineous Han Chinese family with HTX and CHD, and 200 unrelated healthy subjects were enlisted. Exome sequencing and Sanger sequencing were applied to identify the genetic basis of the HTX family. Compound heterozygous variants, c.3426-1G>A and c.4306C>T (p.(Arg1436Trp)), in the dynein axonemal heavy chain 11 gene (DNAH11) were identified in the proband via exome sequencing and further confirmed by Sanger sequencing. Neither c.3426-1G>A nor c.4306C>T variant in the DNAH11 gene was detected in 200 healthy controls. The DNAH11 c.3426-1G>A variant was predicted as altering the acceptor splice site and most likely affecting splicing. The DNAH11 c.4306C>T variant was predicted to be damaging, which may reduce the phenotype severity. The compound heterozygous variants, c.3426-1G>A and c.4306C>T, in the DNAH11 gene might be the pathogenic alterations resulting in HTX and CHD in this family. These findings broaden the variant spectrum of the DNAH11 gene and increase knowledge used in genetic counseling for the HTX family.

Liver Transplantation in a Child with Kartagener Syndrome: A Case Report

Background

Kartagener syndrome (KS) is a rare genetic disorder consisting of the triad of situs inversus, chronic sinusitis, and bronchiectasis. Although there are previous reports regarding the anaesthetic considerations in KS, none have included liver transplantation.

Case Presentation

An 11-year-old boy with a diagnosis of KS underwent liver transplantation due to extrahepatic biliary atresia. Previous diagnostic imaging confirmed situs inversus and the absence of an inferior vena cava. The patient's peak airway pressure intermittently increased intraoperatively from 15 to 30 cm H₂O due to increased pulmonary secretions, which required frequent suctioning of the endotracheal tube. Intraoperative volume resuscitation included 200 mL of 5% albumin, 5 units of erythrocyte suspension and 3 units of fresh frozen plasma. Intermittently, a norepinephrine infusion was required to maintain the MAP. Coagulation function was monitoring using the thromboelastogram to guide the use of blood products including fresh frozen plasma. At the end of the surgery, the patient was transferred to the intensive care unit. He was discharged from the intensive care unit on postoperative day 5, and from the hospital on postoperative day 28. He continues to do well with normal liver function 23 months after surgery.

Conclusion

Despite the risk of pulmonary related to airway secretions and exacerbation of hemodynamic instability related to anatomical variations in the inferior vena cava anatomy, KS patients can be safely anesthetized with careful planning and attention of the disease process, even for complex surgical procedures such as liver transplantation.

Biallelic loss of function NEK3 mutations deacetylate α-tubulin and downregulate NUP205 that predispose individuals to cilia-related abnormal cardiac left-right patterning

Defective left–right (LR) organization involving abnormalities in cilia ultrastructure causes laterality disorders including situs inversus (SI) and heterotaxy (Htx) with the prevalence approximately 1/10,000 births. In this study, we describe two unrelated family trios with abnormal cardiac LR patterning. Through whole-exome sequencing (WES), we identified compound heterozygous mutations (c.805-1G >C; p. Ile269GlnfsTer8/c.1117dupA; p.Thr373AsnfsTer19) (c.29T>C; p.Ile10Thr/c.356A>G; p.His119Arg) of NEK3, encoding a NIMA (never in mitosis A)-related kinase, in two affected individuals, respectively. Protein levels of NEK3 were abrogated in Patient-1 with biallelic loss-of function (LoF) NEK3 mutations that causes premature stop codon. Subsequence transcriptome analysis revealed that NNMT (nicotinamide N-methyltransferase) and SIRT2 (sirtuin2) was upregulated by NEK3 knockdown in human retinal pigment epithelial (RPE) cells in vitro, which associates α-tubulin deacetylation by western blot and immunofluorescence. Transmission electron microscopy (TEM) analysis further identified defective ciliary ultrastructure in Patient-1. Furthermore, inner ring components of nuclear pore complex (NPC) including nucleoporin (NUP)205, NUP188, and NUP155 were significantly downregulated in NEK3-silenced cells. In conclusion, we identified biallelic mutations of NEK3 predispose individual to abnormal cardiac left–right patterning via SIRT2-mediated α-tubulin deacetylation and downregulation of inner ring nucleoporins. Our study suggested that NEK3 could be a candidate gene for human ciliopathies.