Registries and collaborative studies for primary ciliary dyskinesia in Europe

Analyses of 1236 genotyped primary ciliary dyskinesia individuals identify regional clusters of distinct DNA variants and significant genotype-phenotype correlations

BACKGROUND

Primary ciliary dyskinesia (PCD) represents a group of rare hereditary disorders characterised by deficient ciliary airway clearance that can be associated with laterality defects. We aimed to describe the underlying gene defects, geographical differences in genotypes and their relationship to diagnostic findings and clinical phenotypes.

METHODS

Genetic variants and clinical findings (age, sex, body mass index, laterality defects, forced expiratory volume in 1 s (FEV1)) were collected from 19 countries using the European Reference Network's ERN-LUNG international PCD Registry. Genetic data were evaluated according to American College of Medical Genetics and Genomics guidelines. We assessed regional distribution of implicated genes and genetic variants as well as genotype correlations with laterality defects and FEV1.

RESULTS

The study included 1236 individuals carrying 908 distinct pathogenic DNA variants in 46 PCD genes. We found considerable variation in the distribution of PCD genotypes across countries due to the presence of distinct founder variants. The prevalence of PCD genotypes associated with pathognomonic ultrastructural defects (mean 72%, range 47-100%) and laterality defects (mean 42%, range 28-69%) varied widely among countries. The prevalence of laterality defects was significantly lower in PCD individuals without pathognomonic ciliary ultrastructure defects (18%). The PCD cohort had a reduced median FEV1 z-score (-1.66). Median FEV1 z-scores were significantly lower in CCNO (-3.26), CCDC39 (-2.49) and CCDC40 (-2.96) variant groups, while the FEV1 z-score reductions were significantly milder in DNAH11 (-0.83) and ODAD1 (-0.85) variant groups compared to the whole PCD cohort.

CONCLUSION

This unprecedented multinational dataset of DNA variants and information on their distribution across countries facilitates interpretation of the genetic epidemiology of PCD and indicates that the genetic variant can predict diagnostic and phenotypic features such as the course of lung function.

Estimates of primary ciliary dyskinesia prevalence: a scoping review

Background

Primary ciliary dyskinesia (PCD) is a rare multisystem genetic disease caused by dysfunctional motile cilia. Despite PCD being the second most common inherited airway disease after cystic fibrosis, PCD continues to be under-recognised globally owing to nonspecific clinical features and the lack of a gold standard diagnostic test. Commonly repeated prevalence estimates range from one in 10 000 to one in 20 000, based on regional epidemiological studies with known limitations. The purpose of this scoping review was to appraise the PCD literature, to determine the best available global PCD prevalence estimate and to inform the reader about the potential unmet health service needs in PCD. The primary objective of the present study was to systematically review the literature about PCD prevalence estimates.

Methods

A scoping review was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for scoping reviews (PRISMA-ScR) methodology. Included studies estimated PCD prevalence and used cohort, clinical or genomic data. Case reports, conference abstracts, review articles, animal studies or non-English articles were excluded.

Results

A literature review identified 3484 unique abstracts; 34 underwent full-text review and eight met the inclusion/exclusion criteria. Seven articles were based on epidemiological studies of specific geographical regions and provided prevalence estimates that ranged from approximately one to 44.1 in 100 000. Only one study estimated global prevalence, using two large genomic databases, and calculated it to be ∼13.2 in 100 000 (based on pathogenic variants in 29 disease-causing genes).

Conclusions

A population-based genomic approach for estimating global prevalence has found that PCD is much more prevalent than previously cited in the literature. This highlights the potential unmet health service needs of people living with PCD.

Infertility and pregnancy outcomes among adults with primary ciliary dyskinesia

STUDY QUESTION

What is the prevalence of infertility and ectopic pregnancies among individuals with primary ciliary dyskinesia (PCD)?

SUMMARY ANSWER

We found that 39 of 50 men (78%) and 72 of 118 women (61%) with PCD were infertile and that women with PCD had an increased risk of ectopic pregnancies (7.6 per 100 pregnancies, 95% CI 4.7-12.2).

WHAT IS KNOWN ALREADY

PCD is a heterogeneous multiorgan disease caused by mutations in genes required for the function and structure of motile cilia. Previous studies identified a link between PCD and infertility, but original data on prevalence of infertility and risk of ectopic pregnancies, the use and efficacy of medically assisted reproduction (MAR), and the association of fertility with PCD genotype are extremely limited.

STUDY DESIGN SIZE DURATION

We performed a cross-sectional survey about fertility within the Living with PCD study (formerly COVID-PCD). Living with PCD is an international, online, participatory study that collects information directly from people with PCD. People with PCD of any age from anywhere in the world can participate in the study. At the time of the survey, 482 adults with PCD were registered within the Living with PCD study.

PARTICIPANTS/MATERIALS SETTING METHODS

We sent a questionnaire on fertility on 12 July 2022, to all participants older than 18 years enrolled in the Living with PCD study. Responses were collected until 8 March 2023. The fertility questionnaire covered topics related to pregnancy attempts, use of MAR, and pregnancy outcomes. Data were collected via the Research Electronic Data Capture (REDCap) platform. We defined infertility as failure to achieve a clinical pregnancy after 12 months or use of MAR for at least one pregnancy.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 265 of 482 adult participants (55%) completed the fertility questionnaire. Among 168 adults who had tried to conceive, 39 of 50 men (78%) and 72 of 118 women (61%) were infertile. Of the infertile men, 28 had tried MAR, and 17 of them (61%) fathered a child with the help of MAR. Among infertile women, 59 had used MAR, and 41 of them (69%) became pregnant with the help of MAR. In our population, women with PCD showed a relatively high risk of ectopic pregnancies: 1 in 10 women who became pregnant had at least one ectopic pregnancy and 7.6% of pregnancies were ectopic (95% CI 4.7-12.2). We evaluated the association between fertility and affected PCD genes in 46 individuals (11 men, 35 women) with available genetic and fertility information, and found differences between genotypes, e.g. all five women with a mutation in CCDC40 were infertile and all five with DNAH11 were fertile.

LIMITATIONS REASONS FOR CAUTION

The study has limitations, including potential selection bias as people experiencing problems with fertility might be more likely to fill in the questionnaire, which may have influenced our prevalence estimates. We were unable to validate clinical data obtained from participant self-reports owing to the anonymous study design, which is likely to lead to recall bias.

WIDER IMPLICATIONS OF THE FINDINGS

The study underlines the need for addressing infertility in routine PCD care, with a focus on informing individuals with PCD about their increased risk. It emphasizes the utility and efficacy of MAR in PCD-related infertility. Additionally, women attempting conception should be made aware of the increased risk of ectopic pregnancies and seek systematic early consultation to confirm an intrauterine pregnancy. Fertility, efficacy of MAR, and risk for adverse pregnancy outcomes differ between people with PCD-depending on genotypes-and close monitoring and support might be needed from fertility specialists to increase chances of successful conception.

STUDY FUNDING/COMPETING INTERESTS

Our research was funded by the Swiss National Science Foundation, Switzerland (SNSF 320030B_192804), the Swiss Lung Association, Switzerland (2021-08_Pedersen), and we also received support from the PCD Foundation, USA; the Verein Kartagener Syndrom und Primäre Ciliäre Dyskinesie, Germany; the PCD Support UK, UK; and PCD Australia, Australia. M. Goutaki received funding from the Swiss National Science Foundation, Switzerland (PZ00P3_185923). B. Maitre participates in the RaDiCo-DCP funded by INSERM France. The study authors participate in the BEAT-PCD Clinical Research Collaboration supported by the European Respiratory Society. All authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov ID NCT04602481.

Primary Ciliary Dyskinesia

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

Is RPGR-related retinal dystrophy associated with systemic disease? A case series

BACKGROUND

Ciliopathies responsible for retinitis pigmentosa can also cause systemic manifestations. RPGR is a ciliary gene and pathogenic variants in RPGR cause a retinal ciliopathy, the commonest cause of X-linked recessive retinitis pigmentosa. The RPGR protein interacts with numerous other ciliary proteins present in the transition zone of both motile and sensory cilia, and may play an important role in regulating ciliary protein transport. There has been a growing, putative association of RPGR variants with systemic ciliopathies: mainly sino-respiratory infections and primary ciliary dyskinesia.

MATERIALS AND METHODS

Retrospective case series of patients with RPGR-RP presenting to Oxford Eye Hospital with systemic disease.

RESULTS

We report three children with RPGR-related rod-cone dystrophy, all of whom have mutations in the N-terminus of RPGR. Two cases co-presented with confirmed diagnoses of primary ciliary dyskinesia and one case with multiple sino-respiratory symptoms strongly suggestive of primary ciliary dyskinesia. These and all previously reported RPGR co-pathologies relate to ciliopathies and have no other systemic associations.

CONCLUSIONS

The link between RPGR variants and a systemic ciliopathy remains plausible, but currently unproven.

The Palestinian primary ciliary dyskinesia population: first results of the diagnostic and genetic spectrum

Background

Diagnostic testing for primary ciliary dyskinesia (PCD) started in 2013 in Palestine. We aimed to describe the diagnostic, genetic and clinical spectrum of the Palestinian PCD population.

Methods

Individuals with symptoms suggestive of PCD were opportunistically considered for diagnostic testing: nasal nitric oxide (nNO) measurement, transmission electron microscopy (TEM) and/or PCD genetic panel or whole-exome testing. Clinical characteristics of those with a positive diagnosis were collected close to testing including forced expiratory volume in 1 s (FEV₁) Global Lung Index z-scores and body mass index z-scores.

Results

68 individuals had a definite positive PCD diagnosis, 31 confirmed by genetic and TEM results, 23 by TEM results alone, and 14 by genetic variants alone. 45 individuals from 40 families had 17 clinically actionable variants and four had variants of unknown significance in 14 PCD genes. CCDC39, DNAH11 and DNAAF11 were the most commonly mutated genes. 100% of variants were homozygous. Patients had a median age of 10.0 years at diagnosis, were highly consanguineous (93%) and 100% were of Arabic descent. Clinical features included persistent wet cough (99%), neonatal respiratory distress (84%) and situs inversus (43%). Lung function at diagnosis was already impaired (FEV₁ z-score median -1.90 (-5.0-1.32)) and growth was mostly within the normal range (z-score mean -0.36 (-3.03-2.57). 19% individuals had finger clubbing.

Conclusions

Despite limited local resources in Palestine, detailed geno- and phenotyping forms the basis of one of the largest national PCD populations globally. There was notable familial homozygosity within the context of significant population heterogeneity.

Characterization of a DRC1 null variant associated with primary ciliary dyskinesia and female infertility

PROPOSE

We here present a female case with primary ciliary dyskinesia (PCD) and infertility. In this report, we also present the evaluation of the patient family, including her twin sister, also with PCD and infertility.

METHODS

Confirmation of the PCD clinical diagnosis was performed through assessment of cilia motility, by high-speed video microscopy (HSVM), axoneme ultrastructure, by transmission electron microscopy (TEM), and genetic characterization, by whole-exome sequence (WES). Gene expression studies used qPCR for mRNA expression and immunofluorescence to determine cell protein localization.

RESULTS

We identified a homozygous nonsense variant in the DRC1 gene (NM 145038.5:c.352C>T (p.Gln118Ter)) in the female patient with PCD and infertility that fit the model of autosomal recessive genetic transmission. This variant eventually results in a dyskinetic ciliary beat with a lower frequency and a partial lack of both dynein arms as revealed by TEM analysis. Moreover, this variant implies a decrease in the expression of DRC1 mRNA and protein. Additionally, expression analysis suggested that DRC1 may interact with other DRC elements.

CONCLUSIONS

Our findings suggest that the DRC1 null variant leads to PCD associated with infertility, likely caused by defects in axoneme from Fallopian tube cilia. Overall, our outcomes contribute to a better understanding of the genetic factors involved in the pathophysiology of PCD and infertility, and they highlight the interaction of different genes in the patient phenotype, which should be investigated further because it may explain the high heterogeneity observed in PCD patients.

The disease-specific clinical trial network for Primary Ciliary Dyskinesia (PCD-CTN)

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterised by impaired mucociliary clearance leading to irreversible lung damage. In contrast to other rare lung diseases like cystic fibrosis (CF), there are only few clinical trials and limited evidence-based treatments. Management is mainly based on expert opinions and treatment is challenging due to a wide range of clinical manifestations and disease severity. To improve clinical and translational research and facilitate development of new treatments, the clinical trial network for PCD (PCD-CTN) was founded in 2020 under the framework of the European Reference Network (ERN)-LUNG PCD Core. Applications from European PCD sites interested in participating in the PCD-CTN were requested. Inclusion criteria consisted of patient numbers, membership of ERN-LUNG PCD Core, use of associated standards of care, experience in PCD and/or CF clinical research, resources to run clinical trials, good clinical practice (GCP) certifications and institutional support. So far, applications from 22 trial sites in 18 European countries have been approved, including >1400 adult and >1600 paediatric individuals with PCD. The PCD-CTN is headed by a coordinating centre and consists of a steering and executive committee, a data safety monitoring board and committees for protocol review, training and standardisation. A strong association with patient organisations and industrial companies are further cornerstones. All participating trial sites agreed on a code of conduct. As CTNs from other diseases have demonstrated successfully, this newly formed PCD-CTN operates to establish evidence-based treatments for this orphan disease and to bring new personalised treatment approaches to patients.

The disease-specific clinical trial network for primary ciliary dyskinesia (PCD-CTN) was built under the framework of the European Reference Network (ERN)-LUNG PCD Core, and operates to establish evidence-based and new personalised treatment for PCDhttps://bit.ly/3sLtC8o

Chronic airway disease in primary ciliary dyskinesia—spiced with geno–phenotype associations

Primary ciliary dyskinesia (PCD) can be defined as a multiorgan ciliopathy with a dominant element of chronic airway disease affecting the nose, sinuses, middle ear, and in particular, the lower airways. Although most patients with PCD are diagnosed during preschool years, it is obvious that the chronic lung disease starts its course already from birth. The many faces of the clinical picture change, as does lung function, structural lung damage, the burden of infection, and of treatment throughout life. A markedly severe neutrophil inflammation in the respiratory tract seems pervasive and is only to a minimal extent ameliorated by a treatment strategy, which is predominantly aimed at bacterial infections. An ever‐increasing understanding of the different aspects, their interrelationships, and possible different age courses conditioned by the underlying genotype is the focus of much attention. The future is likely to offer personalized medicine in the form of mRNA therapy, but to that end, it is of utmost importance that all patients with PCD be carefully characterized and given a genetic diagnosis. In this narrative review, we have concentrated on lower airways and summarized the current understanding of the chronic airway disease in this motile ciliopathy. In addition, we highlight the challenges, gaps, and opportunities in PCD lung disease research.

Respiratory symptoms of Swiss people with Primary Ciliary Dyskinesia

Background

Mostly derived from chart reviews, where symptoms are recorded in a nonstandardised manner, clinical data about primary ciliary dyskinesia (PCD) are inconsistent, which leads to missing and unreliable information. We assessed the prevalence and frequency of respiratory and ear symptoms and studied differences by age and sex among an unselected population of Swiss people with PCD.

Methods

We sent a questionnaire that included items from the FOLLOW-PCD standardised questionnaire to all Swiss PCD registry participants.

Results

We received questionnaires from 74 (86%) out of 86 invited persons or their caregivers (median age 23 years, range 3–73 years), including 68% adults (≥18 years) and 51% females. Among participants, 70 (94%) reported chronic nasal symptoms; most frequently runny nose (65%), blocked nose (55%) or anosmia (38%). Ear pain and hearing problems were reported by 58% of the participants. Almost all (99%) reported cough and sputum production. The most common chronic cough complications were gastro-oesophageal reflux (n=11; 15%), vomiting (n=8; 11%) and urinary incontinence (n=6; 8%). Only nine (12%) participants reported frequent wheeze, which occurred mainly during infection or exercise, while 49 (66%) reported shortness of breath, and 9% even at rest or during daily activities. Older patients reported more frequent nasal symptoms and shortness of breath. We found no difference by sex or ultrastructural ciliary defect.

Conclusion

This is the first study to describe patient-reported PCD symptoms. The consistent collection of standardised clinical data will allow us to better characterise the phenotypic variability of the disease and study disease course and prognosis.

Detailed information about patient-reported PCD symptoms will help characterise the phenotypic variability of the disease and could inform the development of individualised treatment strategies for patientshttps://bit.ly/363Zb4T

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.

A retrospective review of Achromobacter species and antibiotic treatments in patients with primary ciliary dyskinesia

Objectives: Primary ciliary dyskinesia (PCD) is a rare congenital disease with defective mucociliary clearance causing frequent and often persistent pulmonary infections. Achromobacter species are opportunistic pathogens renowned for the difficulty of effective treatments and deteriorating effects on lung function. We aimed to describe the occurrence, treatment, and rate of successful eradication of Achromobacter species in patients with PCD. Methods: We retrospectively reviewed 18 years of historical microbiological samples and 10 years of electronic health records for PCD patients in Denmark. Results: We included 136 patients. Twenty-six patients had isolates of Achromobacter species. On average, 5% of the cohort had at least one annual isolate. Infections became persistent in 38% with a median length of 6.6 years leading to a significant number of antibiotic treatments. Resistance toward tobramycin and ciprofloxacin was prevalent. Overall, successful eradication was achieved in 62% of patients. We found the course of lung function significantly worse during persistent Achromobacter species infection than during the two preceding years, but not different to the course in unaffected age-matched controls. Conclusion The prevalence of Achromobacter species in patients with PCD is in line with what has been reported in cystic fibrosis and can occur transiently, intermittently, or develop into a serious persistent lung infection associated with long-term antibiotic treatment.

Current and Future Treatments in Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic ciliopathy in which mucociliary clearance is disturbed by the abnormal motion of cilia or there is a severe reduction in the generation of multiple motile cilia. Lung damage ensues due to recurrent airway infections, sometimes even resulting in respiratory failure. So far, no causative treatment is available and treatment efforts are primarily aimed at improving mucociliary clearance and early treatment of bacterial airway infections. Treatment guidelines are largely based on cystic fibrosis (CF) guidelines, as few studies have been performed on PCD. In this review, we give a detailed overview of the clinical studies performed investigating PCD to date, including three trials and several case reports. In addition, we explore precision medicine approaches in PCD, including gene therapy, mRNA transcript and read-through therapy.

A Comprehensive Approach for the Diagnosis of Primary Ciliary Dyskinesia-Experiences from the First 100 Patients of the PCD-UNIBE Diagnostic Center

Primary ciliary dyskinesia (PCD) is a rare genetic disease characterized by dyskinetic cilia. Respiratory symptoms usually start at birth. The lack of diagnostic gold standard tests is challenging, as PCD diagnostics requires different methods with high expertise. We founded PCD-UNIBE as the first comprehensive PCD diagnostic center in Switzerland. Our diagnostic approach includes nasal brushing and cell culture with analysis of ciliary motility via high-speed-videomicroscopy (HSVM) and immunofluorescence labeling (IF) of structural proteins. Selected patients undergo electron microscopy (TEM) of ciliary ultrastructure and genetics. We report here on the first 100 patients assessed by PCD-UNIBE. All patients received HSVM fresh, IF, and cell culture (success rate of 90%). We repeated the HSVM with cell cultures and conducted TEM in 30 patients and genetics in 31 patients. Results from cell cultures were much clearer compared to fresh samples. For 80 patients, we found no evidence of PCD, 17 were diagnosed with PCD, two remained inconclusive, and one case is ongoing. HSVM was diagnostic in 12, IF in 14, TEM in five and genetics in 11 cases. None of the methods was able to diagnose all 17 PCD cases, highlighting that a comprehensive approach is essential for an accurate diagnosis of PCD.

Primary Ciliary Dyskinesia

Primary ciliary dyskinesia (PCD) is an inherited cause of bronchiectasis. The estimated PCD prevalence in children with bronchiectasis is up to 26% and in adults with bronchiectasis is 1 to 13%. Due to dysfunction of the multiple motile cilia of the respiratory tract patients suffer from poor mucociliary clearance. Clinical manifestations are heterogeneous; however, a typical patient presents with chronic productive cough and rhinosinusitis from early life. Other symptoms reflect the multiple roles of motile cilia in other organs and can include otitis media and hearing loss, infertility, situs inversus, complex congenital heart disease, and more rarely other syndromic features such as hydrocephalus and retinitis pigmentosa. Awareness, identification, and diagnosis of a patient with PCD are important for multidisciplinary care and genetic counseling. Diagnosis can be pursued through a multitest pathway which includes the measurement of nasal nitric oxide, sampling the nasal epithelium to assess ciliary function and structure, and genotyping. Diagnosis is confirmed by the identification of a hallmark ultrastructural defect or pathogenic mutations in one of > 45 PCD causing genes. When a diagnosis is established management is centered around improving mucociliary clearance through physiotherapy and treatment of infection with antibiotics. The first international randomized controlled trial in PCD has recently been conducted showing azithromycin is effective in reducing exacerbations. It is likely that evidence-based PCD-specific management guidelines and therapies will be developed in the near future. This article examines prevalence, clinical features, diagnosis, and management of PCD highlighting recent advances in basic science and clinical care.

Implementation of multigene panel NGS diagnosis in the national primary ciliary dyskinesia cohort of Cyprus: An island with a high disease prevalence

We aimed to determine a genetic diagnosis in the national primary ciliary dyskinesia (PCD) cohort of Cyprus, an island with a high disease prevalence. We used targeted next-generation sequencing (NGS) of 39 PCD genes in 48 patients of Greek-Cypriot and other ancestries. We achieved a molecular diagnosis in 74% of the unrelated families tested. We identified 24 different mutations in 11 genes, 12 of which are novel. Homozygosity was more common in Greek-Cypriot than non-Greek-Cypriot patients (88% vs. 46.2%, p = .016). Four mutations (DNAH11:c.5095-2A>G, CFAP300:c.95_103delGCCGGCTCC, TTC25:c.716G>A, RSPH9:c.670+2T>C) were found in 74% of the diagnosed Greek-Cypriot families. Patients with RSPH9 mutations demonstrated higher nasal nitric oxide (57 vs. 15 nl/min, p <.001), higher forced expiratory volume in 1 s (-0.89 vs. -2.37, p = .018) and forced vital capacity (-1.00 vs. -2.16, p = .029) z scores than the rest of the cohort. Targeted multigene-panel NGS is an efficient tool for early diagnosis of PCD, providing insight into genetic disease epidemiology and improved patient stratification.

COVID-PCD: a participatory research study on the impact of COVID-19 in people with primary ciliary dyskinesia

COVID-PCD is a participatory study initiated by people with primary ciliary dyskinesia (PCD) who have an essential vote in all stages of the research from the design of the study to the recruitment of participants, and interpretation and communication of the study results. COVID-PCD aims to collect epidemiological data in real-time from people with PCD throughout the pandemic to describe incidence of coronavirus disease 2019 (COVID-19), symptoms and course of disease; identify risk factors for prognosis; and assess experiences, wishes and needs. The study is advertised through patient support groups and participants register online on the study website (www.covid19pcd.ispm.ch). The study invites persons of any age from anywhere in the world with a suspected or confirmed PCD. A baseline questionnaire assesses details on PCD diagnosis, habitual symptoms and COVID-19 episodes that occurred before study entry. Afterwards, participants receive a weekly follow-up questionnaire with questions on incident severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, current symptoms, social contact behaviour and physical activity. Occasional thematic questionnaires are sent out focussing on emerging questions of interest chosen by people with PCD. In case of hospitalisation, patients or family members are asked to obtain a hospital report. Results are continuously analysed and summaries put online. The study started recruitment on April 30, 2020, and 556 people with PCD completed the baseline questionnaire by November 2, 2020. The COVID-PCD study is a participatory study that follows people with PCD during the COVID-19 pandemic, helps to empower affected persons, and serves as a platform for communication between patients, physicians and researchers.

A retrospective review of Achromobacter species and antibiotic treatments in patients with primary ciliary dyskinesia

Objectives: Primary ciliary dyskinesia (PCD) is a rare congenital disease with defective mucociliary clearance causing frequent and often persistent pulmonary infections. Achromobacter species are opportunistic pathogens renowned for the difficulty of effective treatments and deteriorating effects on lung function. We aimed to describe the occurrence, treatment, and rate of successful eradication of Achromobacter species in patients with PCD. Methods: We retrospectively reviewed 18 years of historical microbiological samples and 10 years of electronic health records for PCD patients in Denmark. Results: We included 136 patients. Twenty-six patients had isolates of Achromobacter species. On average, 5% of the cohort had at least one annual isolate. Infections became persistent in 38% with a median length of 6.6 years leading to a significant number of antibiotic treatments. Resistance toward tobramycin and ciprofloxacin was prevalent. Overall, successful eradication was achieved in 62% of patients. We found the course of lung function significantly worse during persistent Achromobacter species infection than during the two preceding years, but not different to the course in unaffected age-matched controls. Conclusion The prevalence of Achromobacter species in patients with PCD is in line with what has been reported in cystic fibrosis and can occur transiently, intermittently, or develop into a serious persistent lung infection associated with long-term antibiotic treatment.

Motile ciliopathies

Motile cilia are highly complex hair-like organelles of epithelial cells lining the surface of various organ systems. Genetic mutations (usually with autosomal recessive inheritance) that impair ciliary beating cause a variety of motile ciliopathies, a heterogeneous group of rare disorders. The pathogenetic mechanisms, clinical symptoms and severity of the disease depend on the specific affected genes and the tissues in which they are expressed. Defects in the ependymal cilia can result in hydrocephalus, defects in the cilia in the fallopian tubes or in sperm flagella can cause female and male subfertility, respectively, and malfunctional motile monocilia of the left-right organizer during early embryonic development can lead to laterality defects such as situs inversus and heterotaxy. If mucociliary clearance in the respiratory epithelium is severely impaired, the disorder is referred to as primary ciliary dyskinesia, the most common motile ciliopathy. No single test can confirm a diagnosis of motile ciliopathy, which is based on a combination of tests including nasal nitric oxide measurement, transmission electron microscopy, immunofluorescence and genetic analyses, and high-speed video microscopy. With the exception of azithromycin, there is no evidence-based treatment for primary ciliary dyskinesia; therapies aim at relieving symptoms and reducing the effects of reduced ciliary motility.