The prevalence of clinical features associated with primary ciliary dyskinesia in a heterotaxy population: results of a web-based survey

Cystic fibrosis and primary ciliary dyskinesia: Similarities and differences

Cystic fibrosis (CF) and Primary ciliary dyskinesia (PCD) are both rare chronic diseases, inherited disorders associated with multiple complications, namely respiratory complications, due to impaired mucociliary clearance that affect severely patients' lives. Although both are classified as rare diseases, PCD has a much lower prevalence than CF, particularly among Caucasians. As a result, CF is well studied, better recognized by clinicians, and with some therapeutic approaches already available. Whereas PCD is still largely unknown, and thus the approach is based on consensus guidelines, expert opinion, and extrapolation from the larger evidence base available for patients with CF. Both diseases have some clinical similarities but are very different, necessitating different treatment by specialists who are familiar with the complexities of each disease.This review aims to provide an overview of the knowledge about the two diseases with a focus on the similarities and differences between both in terms of disease mechanisms, common clinical manifestations, genetics and the most relevant therapeutic options. We hoped to raise clinical awareness about PCD, what it is, how it differs from CF, and how much information is still lacking. Furthermore, this review emphasises the fact that both diseases require ongoing research to find better treatments and, in particular for PCD, to fill the medical and scientific gaps.

Lung Transplantation for Primary Ciliary Dyskinesia and Kartagener Syndrome: A Multicenter Study

Primary ciliary dyskinesia, with or without situs abnormalities, is a rare lung disease that can lead to an irreversible lung damage that may progress to respiratory failure. Lung transplant can be considered in end-stage disease. This study describes the outcomes of the largest lung transplant population for PCD and for PCD with situs abnormalities, also identified as Kartagener's syndrome. Retrospectively collected data of 36 patients who underwent lung transplantation for PCD from 1995 to 2020 with or without SA as part of the European Society of Thoracic Surgeons Lung Transplantation Working Group on rare diseases. Primary outcomes of interest included survival and freedom from chronic lung allograft dysfunction. Secondary outcomes included primary graft dysfunction within 72 h and the rate of rejection ≥A2 within the first year. Among PCD recipients with and without SA, the mean overall and CLAD-free survival were 5.9 and 5.2 years with no significant differences between groups in terms of time to CLAD (HR: 0.92, 95% CI: 0.27-3.14, p = 0.894) or mortality (HR: 0.45, 95% CI: 0.14-1.43, p = 0.178). Postoperative rates of PGD were comparable between groups; rejection grades ≥A2 on first biopsy or within the first year was more common in patients with SA. This study provides a valuable insight on international practices of lung transplantation in patients with PCD. Lung transplantation is an acceptable treatment option in this population.

Olfaction and Gustation in Children With Primary Ciliary Dyskinesia

Objective

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder whereby abnormal cilia cause a wide array of respiratory tract manifestations including chronic rhinosinusitis. The purpose of this study was to determine whether olfaction and gustation are impaired in children with PCD.

Study Design

Cross-sectional study.

Setting

Tertiary pediatric academic hospital.

Methods

Children with confirmed PCD based on having at least 1 of 3 approved diagnostic criteria as per The American Thoracic Society guidelines were recruited from The PCD Clinic in our tertiary care pediatric hospital. Odor identification ability was tested using the Universal Sniff (U-Sniff) test and taste threshold was measured using an electrogustometer. The main outcome of this study is to determine the incidence of olfactory dysfunction in children with PCD and investigate if there is an associated gustatory dysfunction.

Results

Twenty-five children participated (14 male, 11 female), The median age was 10.8 years (range: 4.1-17.9 years). Only 4/25 (16%) complained of olfactory dysfunction prior to testing. None of the patients complained of dysgeusia. However, 48% (12/25) scored less than 7 on the U-Sniff, signifying hyposmia or anosmia. In contrast, scores obtained by electrogustometry were in the normal range. There was no correlation between performance on the U-Sniff and electrogustometry testing.

Conclusion

Olfactory impairment in children with PCD is common but underrecognized by patients. This is not associated with abnormal gustation. Among other, this places children with PCD at an increased risk with respect to smelling a fire or detecting spoiled or poisonous food.

A multi-disciplinary, comprehensive approach to management of children with heterotaxy

Heterotaxy (HTX) is a rare condition of abnormal thoraco-abdominal organ arrangement across the left-right axis of the body. The pathogenesis of HTX includes a derangement of the complex signaling at the left-right organizer early in embryogenesis involving motile and non-motile cilia. It can be inherited as a single-gene disorder, a phenotypic feature of a known genetic syndrome or without any clear genetic etiology. Most patients with HTX have complex cardiovascular malformations requiring surgical intervention. Surgical risks are relatively high due to several serious comorbidities often seen in patients with HTX. Asplenia or functional hyposplenism significantly increase the risk for sepsis and therefore require antimicrobial prophylaxis and immediate medical attention with fever. Intestinal rotation abnormalities are common among patients with HTX, although volvulus is rare and surgical correction carries substantial risk. While routine screening for intestinal malrotation is not recommended, providers and families should promptly address symptoms concerning for volvulus and biliary atresia, another serious morbidity more common among patients with HTX. Many patients with HTX have chronic lung disease and should be screened for primary ciliary dyskinesia, a condition of respiratory cilia impairment leading to bronchiectasis. Mental health and neurodevelopmental conditions need to be carefully considered among this population of patients living with a substantial medical burden. Optimal care of children with HTX requires a cohesive team of primary care providers and experienced subspecialists collaborating to provide compassionate, standardized and evidence-based care. In this statement, subspecialty experts experienced in HTX care and research collaborated to provide expert- and evidence-based suggestions addressing the numerous medical issues affecting children living with HTX.

Vestibular and Balance Impairment Is Common in Children With Primary Ciliary Dyskinesia

OBJECTIVE

Primary ciliary dyskinesia (PCD) is a rare genetic disorder that presents with a wide range of respiratory complaints. The most common otologic associated disorder is middle ear effusion. We ask if children with PCD suffer from vestibular impairment.

STUDY DESIGN

Cross-sectional cohort study.

SETTING

Tertiary pediatric referral hospital.

PATIENTS/PARTICIPANTS

Children with confirmed PCD.

INTERVENTION/METHODS

All included participants were clinically assessed to be at baseline then basic demographics and medical histories were collected, including the specific genetic mutation these patients have. After which, all patients underwent two vestibular tests. The first was to assess their ability to stand on one foot with their eyes open and then with their eyes closed and the second was video head impulse test (vHIT).

MAIN OUTCOME MEASURES

Ability standing on one foot with the eyes closed and vHIT.

RESULTS

During this period, 25 children with PCD were recruited for the study. The mean age at recruitment was 11.26 years (4-18 yr). There were 11 women and 14 men. All patients were able to participate in both tests. Nineteen participants (76%) had vestibular impairment. Fifteen of them failed to stand on one foot with their eyes closed and six of 25 had abnormal vHIT. The most common involved gene was DNAH5 8/25 (32%) and it was associated with vestibular impairment in seven of eight participants (87.5%).

CONCLUSION

The majority of children with PCD that we tested suffered from vestibular impairment that was previously undiagnosed. This potentially indicates that imbalance and vestibular pathology is under-diagnosed in children with PCD.

A Rare Case of Recurrent Pneumonia in Heterotaxy Syndrome, Polysplenia/Left Isomerism

Heterotaxy syndrome (HS) or situs ambiguous refers to the abnormal arrangement of viscera across the body axis, and abnormalities arise depending on the isomerism of the right or left atrial appendage. The cause remains unexplained and is attributed to a combination of genetic mutations and environmental factors. It is a rare condition and may remain undiagnosed for a long time. In this report, we aim to highlight an unusual presentation and aggravation of an infection due to the underlying isomerism of the left atrial appendage. We discuss the case of a female patient who presented with symptoms of fever and cough. The patient underwent prolonged antibiotic treatment, and her recovery was slow. The presence of bilobed lungs, vertical left-bronchus, and polysplenia on CT scan explained the left-sided aspiration pneumonia. The hypofunctioning spleen (polysplenia) caused her to have a weak immunological response, necessitating prolonged antibiotic use. She was followed up over time and had a recurrence of pneumonia within a few months. The condition is associated with high morbidity and mortality, and the role of early diagnosis and reporting to prevent complications is paramount. The recurrent pneumonia observed in the patient also raises questions related to long-term antibiotic use and immunization in the case of polysplenia in this patient population.

A novel heterotaxy gene: Expansion of the phenotype of TTC21B-spectrum disease

TTC21B encodes the protein IFT139, a critical component of the retrograde transport system within the primary cilium. Biallelic, pathogenic TTC21B variants are associated with classic ciliopathy syndromes, including nephronophthisis, Jeune asphyxiating thoracic dystrophy, and Joubert Syndrome, with ciliopathy‐spectrum traits such as biliary dysgenesis, primary ciliary dyskinesia, and situs inversus, and also with focal segmental glomerulosclerosis. We report a 9‐year‐old male with focal segmental glomerulosclerosis requiring kidney transplant, primary ciliary dyskinesia, and biliary dysgenesis, found by research‐based exome sequencing to have biallelic pathogenic TTC21B variants. A sibling with isolated heterotaxy was found to harbor the same variants. This case highlights the phenotypic spectrum and unpredictable manifestations of TTC21B‐related disease, and also reports the first association between TTC21B and heterotaxy, nominating TTC21B as an important new heterotaxy gene.

Phenotypic features of ciliary dyskinesia among patients with congenital cardiovascular malformations

BACKGROUND

Cilia are cell membrane-bound organelles responsible for airway mucus clearance, establishment of left-right organ asymmetry, cardiogenesis, and many other functions in utero. Phenotypic features suggestive of respiratory ciliary dyskinesia among patients with heterotaxy syndrome, defined as complex cardiovascular malformations (CVM) and situs ambiguus (SA), has not been adequately explored.

OBJECTIVES

We hypothesized that there is a greater incidence of phenotypic features consistent with ciliary dyskinesia among patients with heterotaxy syndrome compared to patients with other CVM and laterality defects without heterotaxy syndrome.

METHODS

Thirty six subjects were identified by medical record search and divided into four groups based on situs status and type of CVM as follows: SA and complex CVM (group 1); SA and simple CVM (group 2); situs solitus and complex CVM (group 3); and situs solitus and simple CVM (group 4). Phenotype was assessed with a clinical questionnaire, nasal nitric oxide (NO) level, and pulmonary function testing. Those with complex CVM underwent additional testing for variants in genes involved in ciliary structure and function.

RESULTS

The mean nasal NO level was significantly lower among all subjects with complex CVM regardless of situs anomalies (groups 1 and 3). There was no significant difference in respiratory symptoms or lung function among the four groups. No bi-allelic genetic mutations were detected among patients with complex CVM.

CONCLUSIONS

This study identified a relatively lower mean nasal NO level, suggestive of relative ciliary dyskinesia, among subjects with complex CVM. Pulmonary function and clinical symptoms did not reflect significant pulmonary disease among those with complex CVM.

Genetic Basis for Congenital Heart Disease: Revisited: A Scientific Statement From the American Heart Association

This review provides an updated summary of the state of our knowledge of the genetic contributions to the pathogenesis of congenital heart disease. Since 2007, when the initial American Heart Association scientific statement on the genetic basis of congenital heart disease was published, new genomic techniques have become widely available that have dramatically changed our understanding of the causes of congenital heart disease and, clinically, have allowed more accurate definition of the pathogeneses of congenital heart disease in patients of all ages and even prenatally. Information is presented on new molecular testing techniques and their application to congenital heart disease, both isolated and associated with other congenital anomalies or syndromes. Recent advances in the understanding of copy number variants, syndromes, RASopathies, and heterotaxy/ciliopathies are provided. Insights into new research with congenital heart disease models, including genetically manipulated animals such as mice, chicks, and zebrafish, as well as human induced pluripotent stem cell-based approaches are provided to allow an understanding of how future research breakthroughs for congenital heart disease are likely to happen. It is anticipated that this review will provide a large range of health care-related personnel, including pediatric cardiologists, pediatricians, adult cardiologists, thoracic surgeons, obstetricians, geneticists, genetic counselors, and other related clinicians, timely information on the genetic aspects of congenital heart disease. The objective is to provide a comprehensive basis for interdisciplinary care for those with congenital heart disease.

The prevalence of the defining features of primary ciliary dyskinesia within a cri du chat syndrome cohort

BACKGROUND

Primary ciliary dyskinesia (PCD) and cri du chat syndrome (CdCS) are distinct disorders that can co-occur due to a common genetic locus on chromosome 5p. Chronic respiratory symptoms associated with PCD can occur in CdCS and are typically attributed to hypotonia, dysphagia, and aspiration. The prevalence of PCD among individuals with CdCS is not known.

METHODS

An online survey assessing common features of PCD was distributed to members of the 5P Minus Society, a cri du chat patient advocacy group. Respondents who met criteria for elevated risk of PCD (at least 3 symptoms or other features highly suggestive of PCD) were offered PCD genetic testing.

RESULTS

For the 123 respondents (median age 10.1 years with IQR 5.5-17.3 years; from 33 U.S. states and 10 other countries) chronic respiratory symptoms associated with PCD were prevalent, including unexplained neonatal respiratory distress, year-round nasal congestion beginning in infancy, and year-round, wet cough beginning in infancy in 35%, 32%, and 20% of respondents, respectively. Fifteen respondents (12%) met criteria for elevated risk for PCD and completed genetic analysis; however, none were diagnostic for PCD. A PCD clinical center evaluated an additional subject with CdCS who met criteria for likely PCD and had negative genetics, but had diagnostic electron microscopy of the respiratory cilia (missing outer dynein arms).

CONCLUSION

Clinicians should be aware of the genetic connection between CdCS and PCD. Non-informative genetic testing does not rule out PCD. CdCS patients with chronic respiratory symptoms may benefit from referral to specialized PCD diagnostic centers.

To beat, or not to beat, that is question! The spectrum of ciliopathies

Cilia are widely distributed throughout the human body, and have numerous roles in physiology, development, and disease. Ciliary ultrastructure is complex, consisting of nine parallel microtubules doublets, with or without motor dynein arms and a central pair of microtubules. Classification of cilia has evolved over time, and currently, four main classes are described: motile and non-motile cilia with a "9 + 2" structure, and motile and non-motile cilia with a "9 + 0" structure, which depend on the presence or absence of dynein arms and a central pair. Ciliopathies are inherited multisystem disorders of cilia, and may present with a varied spectrum of genotypes and phenotypes. Motor and sensory ciliopathies were historically considered as distinct dysfunctions of motile and non-motile cilia, but recent data indicate that the classical features of motor and sensory cilia may overlap.

Clinical manifestations in primary ciliary dyskinesia: systematic review and meta-analysis

Few original studies have described the prevalence and severity of clinical symptoms of primary ciliary dyskinesia (PCD). This systematic review and meta-analysis aimed to identify all published studies on clinical manifestations of PCD patients, and to describe their prevalence and severity stratified by age and sex.We searched PubMed, Embase and Scopus for studies describing clinical symptoms of ≥10 patients with PCD. We performed meta-analyses and meta-regression to explain heterogeneity.We included 52 studies describing a total of 1970 patients (range 10-168 per study). We found a prevalence of 5% for congenital heart disease. For the rest of reported characteristics, we found considerable heterogeneity (I² range 68-93.8%) when calculating the weighted mean prevalence. Even after taking into account the explanatory factors, the largest part of the between-studies variance in symptom prevalence remained unexplained for all symptoms. Sensitivity analysis including only studies with test-proven diagnosis showed similar results in prevalence and heterogeneity.Large differences in study design, selection of study populations and definition of symptoms could explain the heterogeneity in symptom prevalence. To better characterise the disease, we need larger, multicentre, multidisciplinary, prospective studies that include all age groups, use uniform diagnostics and report on all symptoms.

Congenital Heart Disease and Primary Ciliary Dyskinesia

Through the better understanding of the genetics and clinical associations of Primary Ciliary Dyskinesia (PCD), an autosomal recessive disorder of ciliary motility and mucociliary clearance, the association between PCD and heterotaxic congenital heart disease (CHD) has been established. In parallel, research into the cause of CHD has elucidated further the role of ciliary function on the development of normal cardiovascular structure. Increased awareness by clinicians regarding this elevated risk of PCD in patients with CHD will allow for more comprehensive screening and identification of cases in this high-risk group with earlier diagnosis leading to improved health outcomes.

When to suspect primary ciliary dyskinesia in children

Primary ciliary dyskinesia [PCD] is an uncommon, autosomal recessively inherited condition that is often overlooked and undertreated in childhood. Amidst the myriad of children with coloured nasal secretions, otitis media and a wet cough, there exists a subset with PCD as the underlying unifying diagnosis. In this paper we have highlighted the varying clinical manifestations of PCD, emphasising different presentations between neonates, toddlers, school aged children and adults.

Diagnosis, monitoring, and treatment of primary ciliary dyskinesia: PCD foundation consensus recommendations based on state of the art review

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous, rare lung disease resulting in chronic oto-sino-pulmonary disease in both children and adults. Many physicians incorrectly diagnose PCD or eliminate PCD from their differential diagnosis due to inexperience with diagnostic testing methods. Thus far, all therapies used for PCD are unproven through large clinical trials. This review article outlines consensus recommendations from PCD physicians in North America who have been engaged in a PCD centered research consortium for the last 10 years. These recommendations have been adopted by the governing board of the PCD Foundation to provide guidance for PCD clinical centers for diagnostic testing, monitoring, and appropriate short and long-term therapeutics in PCD patients.