Primary ciliary dyskinesia and newborn respiratory distress

Neonatal diagnosis of primary ciliary dyskinesia in a high consanguinity population: a single tertiary center experience

Though PCD usually presents after birth in term neonates, diagnosing PCD during the neonatal and infancy stages is uncommon, particularly in children who do not exhibit laterality defects. We report our recent experience with the diagnosis of PCD in the neonatal and early infantile period in a highly consanguine population. This was achieved by implementing a novel genetic-based diagnostic approach based on direct testing for recognized regional genetic variants. We conducted a retrospective analysis of children diagnosed with PCD at Soroka University Medical Center during the neonatal or early infantile period between 2020 and 2023. We included children under 3 months of age who had a genetic confirmation of PCD, as evidenced by the presence of two pathogenic variants in recognized genes. Genetic testing targeted regional genetic variants in previously identified PCD genes. Eight patients were included. The median age at diagnosis was 12.5 days. Three (38%) were born prematurely < 34 weeks gestational age. All patients were presented with respiratory distress and hypoxemia after birth. The median duration of oxygen support was 23 days, and upper lobe atelectasis was present in five patients (63%). Congenital cardiac malformation was present in four patients. Organ laterality defects were present in four patients. Genetic mutations identified were in the DNAAF5, DNAL1, DNAAF3, and DNAH1 genes.     Conclusion: Neonatal diagnosis of PCD is uncommon, especially in atypical presentations such as children without laterality defects or preterms. Focusing on a genetic diagnosis of the local tribal pathogenic variants promotes a potential cost-efficient test leading to earlier diagnosis. There is a need for a standardized protocol for earlier diagnosis of PCD in high-consanguinity areas. What is Known: • Primary ciliary dyskinesia (PCD) typically presents after birth in term neonates. • Diagnosing PCD during neonatal and infancy stages is challenging, particularly in children without laterality defects. What is New: • A novel genetic-based diagnostic approach was implemented on the neonatal population in a highly consanguine community, focusing on direct testing for regional genetic variants, leading to early and rapid diagnosis of PCD.

Clinical and genetic spectrum of primary ciliary dyskinesia in children

Primary ciliary dyskinesia is a rare genetically determined pathology that leads to chronic inflammatory damage to the respiratory tract, hearing organs and impaired fertility. This article presents the preliminary results of a study conducted in the clinic aimed at the possibility of predicting the clinical course of the disease depending on the genetic variants of the disease, which enables, with timely diagnosis, personalizing the approach to the treatment of children with such a disabling disease as primary ciliary dyskinesia.Purpose. To determine the clinical and genetic variants of primary ciliary dyskinesia, and to identify patterns of disease development. Material and methods. The study included children from 0 to 18 years old with a verified defect of the ciliary apparatus, by analyzing the mobility of the cilia of the ciliary epithelium of the mucous membrane of the respiratory tract, and who underwent a next generation sequencing exome study.Results. The study revealed characteristic patterns of target organ damage, prevailing in a group of children with impaired cilia assembly factor, as well as in a group of children with damaged dynein arms.Conclusion. Thus, conducting a genetic examination in children with suspected primary ciliary dyskinesia is relevant not only to confirm the disease, but also to predict the course of the disease.

Da Vinci robot-assisted pancreato-duodenectomy in a patient with situs inversus totalis: A case report and review of literature

BACKGROUND

Situs inversus totalis (SIT) is an extremely rare congenital malformation characterized by mirror displacement of the thoracoabdominal organs such as the heart, liver, spleen, and stomach. Herein, we describe a patient with SIT complicated with cholangiocarcinoma who underwent successful pancreaticoduodenectomy with the assistance of a da Vinci robot.

CASE SUMMARY

A 58-year-old female presented to the hospital with paroxysmal pain in her left upper abdomen, accompanied by jaundice and staining of the sclera as chief complaints. Imaging examination detected a mass at the distal end of the common bile duct, with inverted thoracic and abdominal organs. Endoscopic retrograde cholangiopancreatography forceps biopsy revealed the presence of a well-differentiated adenocarcinoma. The patient successfully underwent robotic-assisted pancreaticoduodenectomy; the operation lasted 300 min, the intraoperative blood loss was 500 mL, and there were no intraoperative and postoperative complications.

CONCLUSION

SIT is not directly related to the formation of cholangiocarcinoma. Detailed preoperative imaging examination is conducive to disease diagnosis and also convenient for determining the feasibility of tumor resection. Robot-assisted pancreaticoduodenectomy for SIT complicated with cholangiocarcinoma provides a safe, feasible, minimally invasive, and complication-free alternative with adequate preoperative planning combined with meticulous intraoperative procedures.

[Dyspnea and situs inversus in a boy aged 3 days]

A boy was admitted on day 3 after birth due to shortness of breath for 2 days and cyanosis for 1 day. He had clinical manifestations of dyspnea in the early postnatal period and situs inversus, and was finally diagnosed with Kartagener syndrome. His condition was improved after oxygen therapy, anti-infective therapy, and aerosol therapy. The genetic testing showed that there was a large-fragment loss of heterozygosity, exon 48_50, and a hemizygous mutation, c.7915C > T(p.R2639X), in the DNAH5 gene. Kartagener syndrome is a rare autosomal recessive disease, and this is the first case of Kartagener syndrome diagnosed in the neonatal period in China.

Lessons From Unilateral Loss of Cilia: Early Nasal Nitric Oxide Gas Mixing and the Role of Sinus Patency in Determining Nasal Nitric Oxide

Nasal nitric oxide (nNO) measurement is a diagnostic test for primary ciliary dyskinesia (PCD). Here, we have shown the development of unilateral PCD-like symptoms associated with low nNO. A 60-year-old man had been previously healthy but developed unilateral, severe pansinusitis. He required surgical drainage of all left sinuses, and biopsies showed loss of the ciliated epithelium. At 4 weeks, he had unilateral (left-sided), profuse, clear rhinorrhea characteristic of PCD, and his surgical ostia were all patent endoscopically. His left-sided nNO was less than the right side by 37 ± 1.2 nL/min; this difference decreased to 18 ± 0.87 nL/min at 5 weeks and was gone by 6 weeks when his symptoms resolved. Measurements of 2- and 10-second measurements, in addition to standard nNO measurements, identified this discordance. We conclude that nNO reflects, in part, the production of NO by the ciliated epithelium, not just in the absence or occlusion of sinuses. Early (nasal/sinus volume) measures may be better for diagnosing PCD in than standard, steady-state assays in certain populations.

Primary Ciliary Dyskinesia: An Update on Clinical Aspects, Genetics, Diagnosis, and Future Treatment Strategies

Primary ciliary dyskinesia (PCD) is an orphan disease (MIM 244400), autosomal recessive inherited, characterized by motile ciliary dysfunction. The estimated prevalence of PCD is 1:10,000 to 1:20,000 live-born children, but true prevalence could be even higher. PCD is characterized by chronic upper and lower respiratory tract disease, infertility/ectopic pregnancy, and situs anomalies, that occur in ≈50% of PCD patients (Kartagener syndrome), and these may be associated with congenital heart abnormalities. Most patients report a daily year-round wet cough or nose congestion starting in the first year of life. Daily wet cough, associated with recurrent infections exacerbations, results in the development of chronic suppurative lung disease, with localized-to-diffuse bronchiectasis. No diagnostic test is perfect for confirming PCD. Diagnosis can be challenging and relies on a combination of clinical data, nasal nitric oxide levels plus cilia ultrastructure and function analysis. Adjunctive tests include genetic analysis and repeated tests in ciliary culture specimens. There are currently 33 known genes associated with PCD and correlations between genotype and ultrastructural defects have been increasingly demonstrated. Comprehensive genetic testing may hopefully screen young infants before symptoms occur, thus improving survival. Recent surprising advances in PCD genetic designed a novel approach called "gene editing" to restore gene function and normalize ciliary motility, opening up new avenues for treating PCD. Currently, there are no data from randomized clinical trials to support any specific treatment, thus, management strategies are usually extrapolated from cystic fibrosis. The goal of treatment is to prevent exacerbations, slowing the progression of lung disease. The therapeutic mainstay includes airway clearance maneuvers mainly with nebulized hypertonic saline and chest physiotherapy, and prompt and aggressive administration of antibiotics. Standardized care at specialized centers using a multidisciplinary approach that imposes surveillance of lung function and of airway biofilm composition likely improves patients' outcome. Pediatricians, neonatologists, pulmonologists, and ENT surgeons should maintain high awareness of PCD and refer patients to the specialized center before sustained irreversible lung damage develops. The recent creation of a network of PCD clinical centers, focusing on improving diagnosis and treatment, will hopefully help to improve care and knowledge of PCD patients.

Flexural Rigidity and Shear Stiffness of Flagella Estimated from Induced Bends and Counterbends

Motile cilia and flagella are whiplike cellular organelles that bend actively to propel cells or move fluid in passages such as airways, brain ventricles, and the oviduct. Efficient motile function of cilia and flagella depends on coordinated interactions between active forces from an array of motor proteins and passive mechanical resistance from the complex cytoskeletal structure (the axoneme). However, details of this coordination, including axonemal mechanics, remain unclear. We investigated two major mechanical parameters, flexural rigidity and interdoublet shear stiffness, of the flagellar axoneme in the unicellular alga Chlamydomonas reinhardtii. Combining experiment, theory, and finite element models, we demonstrate that the apparent flexural rigidity of the axoneme depends on both the intrinsic flexural rigidity (EI) and the elastic resistance to interdoublet sliding (shear stiffness, ks). We estimated the average intrinsic flexural rigidity and interdoublet shear stiffness of wild-type Chlamydomonas flagella in vivo, rendered immotile by vanadate, to be EI = 840 ± 280 pN⋅μm(2) and ks = 79.6 ± 10.5 pN/rad, respectively. The corresponding values for the pf3; cnk11-6 double mutant, which lacks the nexin-dynein regulatory complex (N-DRC), were EI = 1011 ± 183 pN·μm(2) and ks = 39.3 ± 6.0 pN/rad under the same conditions. Finally, in the pf13A mutant, which lacks outer dynein arms and inner dynein arm c, the estimates were EI = 777 ± 184 pN·μm(2) and ks = 43.3 ± 7.7 pN/rad. In the two mutant strains, the flexural rigidity is not significantly different from wild-type (p > 0.05), but the lack of N-DRC (in pf3; cnk11-6) or dynein arms (in pf13A) significantly reduces interdoublet shear stiffness. These differences may represent the contributions of the N-DRCs (∼40 pN/rad) and residual dynein interactions (∼35 pN/rad) to interdoublet sliding resistance in these immobilized Chlamydomonas flagella.

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.

Diagnostic Methods in Primary Ciliary Dyskinesia

Diagnosing primary ciliary dyskinesia is difficult. With no reference standard, a combination of tests is needed; most tests require expensive equipment and specialist scientists. We review the advances in diagnostic testing over the past hundred years, with emphasis on recent advances. We particularly focus on use of high-speed video analysis, transmission electron microscopy, nasal nitric oxide and genetic testing. We discuss the international efforts that are in place to advance the evidence base for diagnostic tests.

Establishing normative nasal nitric oxide values in infants

INTRODUCTION

Primary ciliary dyskinesia (PCD), a disease of impaired respiratory cilia motility, is often difficult to diagnose. Recent studies show low nasal nitric oxide (nNO) is closely linked to PCD, allowing the use of nNO measurement for PCD assessments. Nasal NO cutoff values for PCD are stratified by age, given nNO levels normally increase with age. However, normative values for nNO have not been established for infants less than 1 year old. In this study, we aim to establish normative values for nNO in infants and determine their utility in guiding infant PCD assessment.

METHODS AND RESULTS

We obtained 42 nNO values from infants less than 1 year old without a history of PCD or recurrent sinopulmonary disease. Using regression analysis, we estimated the mean age-adjusted nNO values and established a 95% prediction interval (PI) for normal nNO. Using these findings, we were able to show 14 of 15 infant PCD patients had abnormally low nNO with values below the 95% PI.

CONCLUSIONS

In this study we determined a regression model that best fits normative nNO values for infants less than 1 year old. This model identified the majority of PCD infants as having abnormally low nNO. These findings suggest nNO measurement can help guide PCD assessment in infants, and perhaps other pulmonary diseases with a link to low nNO. With early assessments, earlier clinical intervention may be possible to slow disease progression and help reduce pulmonary morbidity.

Presentation of primary ciliary dyskinesia in children: 30 years' experience

AIM

Primary ciliary dyskinesia (PCD) is a rare (1:15,000) condition resulting in recurrent suppurative respiratory tract infections, progressive lung damage and hearing impairment. As the diagnosis is often delayed for years, the purpose of this study was to review the presenting features of children with PCD attending Australia's initial diagnostic PCD service over a 30-year period.

METHOD

A retrospective review of the symptoms of children diagnosed with PCD at Concord Hospital between 1982 and 2012 was undertaken.

RESULTS

One thousand thirty-seven paediatric patients were referred for assessment and underwent nasal ciliary brushing. Eighty-four (8.1%) had PCD based on microscopic analysis of nasal cilia. This included 81 with ciliary ultrastructural abnormalities demonstrated on electron microscopy and 3 with a suggestive phenotype, reduced ciliary beat frequency and a family history of PCD. The median age at diagnosis was 6.4 years (range 0.1 to 18.2 years). Forty-six per cent had situs abnormalities and 31% had a family member with PCD. Recurrent cough (81%), rhinosinusitis (71%), recurrent otitis media (49%) and neonatal respiratory distress (57%) were reported. Bronchiectasis at presentation was documented in 32%. Situs abnormalities and neonatal respiratory distress were present together in 26%.

CONCLUSION

PCD remains under-recognised by health-care workers. The combination of neonatal respiratory distress, chronic suppurative cough and rhinosinusitis was the most common documented symptom cluster at presentation in cases of PCD. A heightened awareness of the clinical features of the disease may help to lower the age at diagnosis, facilitate appropriate treatment and improve long-term outcomes.

Primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder of cilia structure, function, and biogenesis leading to chronic infections of the respiratory tract, fertility problems, and disorders of organ laterality. The diagnosis can be challenging, using traditional tools such as characteristic clinical features, ciliary function, and ultrastructural defects and newer screening tools such as nasal nitric oxide levels and genetic testing add to the diagnostic algorithm. There are 32 known PCD-causing genes, and in the future, comprehensive genetic testing may screen young infants before developing symptoms, thus improving survival. Therapies include surveillance of pulmonary function and microbiology, in addition to airway clearance, antibiotics, and early referral to bronchiectasis centers. As with cystic fibrosis (CF), standardized care at specialized centers using a multidisciplinary approach likely improves outcomes. In conjunction with the CF foundation, the PCD foundation, with experienced investigators and clinicians, is developing a network of PCD clinical centers to coordinate the effort in North America and Europe. As the network grows, clinical care and knowledge will improve.

Primary ciliary dyskinesia: overlooked and undertreated in children

Primary ciliary dyskinesia (PCD) is a multi-organ disorder associated with chronic oto-sino-pulmonary disease, neonatal respiratory distress, situs abnormalities and reduced fertility. Repeated respiratory tract infections leads to the almost universal development of bronchiectasis. These clinical manifestations are a consequence of poorly functioning motile cilia. However, confirming the diagnosis is quite difficult and is often delayed, so the true incidence of PCD may be significantly higher than current estimates. Nasal nitric oxide has been earmarked as a useful screening tool for identifying patients, but its use is limited in pre-school-aged children. Due to the rarity of PCD, the evidence base for management is somewhat limited, and treatment regimens are extrapolated from other suppurative lung disorders, like cystic fibrosis.

Primary ciliary dyskinesia and neonatal respiratory distress

BACKGROUND AND OBJECTIVE

Primary ciliary dyskinesia (PCD) is a rare inherited disease affecting motile cilia lining the respiratory tract. Despite neonatal respiratory distress as an early feature, diagnosis is typically delayed until late childhood. Our objective was to identify characteristics that differentiate PCD from common causes of term neonatal respiratory distress.

METHODS

This was a case-control study. Patients with PCD born after 1994 attending a regional PCD clinic who had a history of neonatal respiratory distress (n = 46) were included. Controls (n = 46), term neonates with respiratory distress requiring a chest radiograph, were randomly selected from hospital birth records and matched on gender, birth month/year, and mode of delivery. Multiple logistic regression was used to determine the association between neonatal characteristics and PCD diagnosis. The diagnostic performance of the best predictive variables was estimated by calculating sensitivity and specificity.

RESULTS

PCD cases required more oxygen therapy (39 cases, 29 controls, P = .01), longer duration of oxygen therapy (PCD mean = 15.2 days, control mean = 0.80 days, P < .01), had later onset of neonatal respiratory distress (PCD median = 12 hours, control median = 1 hour, P < .001), and higher frequency of lobar collapse and situs inversus (PCD = 70% and 48% respectively, control = 0% for both, P < .001). Situs inversus, lobar collapse, or oxygen need for >2 days had 87% (95% confidence interval: 74-94) sensitivity and 96% (95% confidence interval: 85-99) specificity for PCD.

CONCLUSIONS

When encountering term neonates with unexplained respiratory distress, clinicians should consider PCD in those with lobar collapse, situs inversus, and/or prolonged oxygen therapy (>2 days).

Genetics, diagnosis, and future treatment strategies for primary ciliary dyskinesia

INTRODUCTION

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder resulting in chronic oto-sino-pulmonary disease. While PCD is estimated to occur in 1 in 20,000 individuals, fewer than 1,000 patients in the US have a well-established diagnosis.

AREAS COVERED

We provide an overview of the clinical manifestations of PCD, describe the evolution of diagnostic methods, and critique the literature on management of PCD.

EXPERT OPINION

Although interest in clinical studies in non-CF bronchiectasis has increased in recent years, some of whom enroll patients with PCD, the literature regarding therapy for PCD as a distinct entity is lacking, as the numbers are small, and there have been no sub-analyses published. However, with improved screening and diagnostic methods, the development of clinical and research consortiums, and actively enrolling registries of PCD patients, the environment is conducive to perform longitudinal studies of disease course and therapeutic studies to alter that course.

Management of primary ciliary dyskinesia/Kartagener's syndrome in infertile male patients and current progress in defining the underlying genetic mechanism

Kartagener's syndrome (KS) is an autosomal recessive genetic disease accounting for approximately 50% of the cases of primary ciliary dyskinesia (PCD). As it is accompanied by many complications, PCD/KS severely affects the patient's quality of life. Therapeutic approaches for PCD/KS aim to enhance prevention, facilitate rapid definitive diagnosis, avoid misdiagnosis, maintain active treatment, control infection and postpone the development of lesions. In male patients, sperm flagella may show impairment in or complete absence of the ability to swing, which ultimately results in male infertility. Assisted reproductive technology will certainly benefit such patients. For PCD/KS patients with completely immotile sperm, intracytoplasmic sperm injection may be very important and even indispensable. Considering the number of PCD/KS susceptibility genes and mutations that are being identified, more extensive genetic screening is indispensable in patients with these diseases. Moreover, further studies into the potential molecular mechanisms of these diseases are required. In this review, we summarize the available information on various aspects of this disease in order to delineate the therapeutic objectives more clearly, and clarify the efficacy of assisted reproductive technology as a means of treatment for patients with PCD/KS-associated infertility.

Enhanced response to pulmonary Streptococcus pneumoniae infection is associated with primary ciliary dyskinesia in mice lacking Pcdp1 and Spef2

Background

Lower airway abnormalities are common in patients with primary ciliary dyskinesia (PCD), a pediatric syndrome that results from structural or functional defects in motile cilia. Patients can suffer from recurrent bacterial infection in the lung, bronchiectasis, and respiratory distress in addition to chronic sinusitis, otitis media, infertility, and laterality defects. However, surprisingly little is known about the pulmonary phenotype of mouse models of this disorder.

Results

The pulmonary phenotype of two mouse models of PCD, nm1054 and bgh, which lack Pcdp1 and Spef2, respectively, was investigated by histological and immunohistochemical analysis. In addition, both models were challenged with Streptococcus pneumoniae, a common respiratory pathogen found in the lungs of PCD patients. Histopathological analyses reveal no detectable cellular, developmental, or inflammatory abnormalities in the lower airway of either PCD model. However, exposure to S. pneumoniae results in a markedly enhanced inflammatory response in both models. Based on analysis of inflammatory cells in bronchoalveolar lavage fluid and flow cytometric analysis of cytokines in the lung, the bgh model shows a particularly dramatic lymphocytic response by 3 days post-infection compared to the nm1054 model or wild type animals.

Conclusions

Defects in ciliary motility result in a severe response to pulmonary infection. The PCD models nm1054 and bgh are distinct and clinically relevant models for future studies investigating the role of mucociliary clearance in host defense.

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

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia that leads to oto-sino-pulmonary diseases and organ laterality defects in approximately 50% of cases. The estimated incidence of PCD is approximately 1 per 15,000 births, but the prevalence of PCD is difficult to determine, primarily because of limitations in diagnostic methods that focus on testing ciliary ultrastructure and function. Diagnostic capabilities have recently benefitted from (1) documentation of low nasal nitric oxide production in PCD and (2) discovery of biallelic mutations in multiple PCD-causing genes. The use of these complementary diagnostic approaches shows that at least 30% of patients with PCD have normal ciliary ultrastructure. More accurate identification of patients with PCD has also allowed definition of a strong clinical phenotype, which includes neonatal respiratory distress in >80% of cases, daily nasal congestion and wet cough starting soon after birth, and early development of recurrent/chronic middle-ear and sinus disease. Recent studies, using advanced imaging and pulmonary physiologic assessments, clearly demonstrate early onset of lung disease in PCD, with abnormal air flow mechanics by age 6-8 years that is similar to cystic fibrosis, and age-dependent onset of bronchiectasis. The treatment of PCD is not standardized, and there are no validated PCD-specific therapies. Most patients with PCD receive suboptimal management, which should include airway clearance, regular surveillance of pulmonary function and respiratory microbiology, and use of antibiotics targeted to pathogens. The PCD Foundation is developing a network of clinical centers, which should improve diagnosis and management of PCD.

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

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder of motile cilia that leads to oto-sino-pulmonary diseases and organ laterality defects in approximately 50% of cases. The estimated incidence of PCD is approximately 1 per 15,000 births, but the prevalence of PCD is difficult to determine, primarily because of limitations in diagnostic methods that focus on testing ciliary ultrastructure and function. Diagnostic capabilities have recently benefitted from (1) documentation of low nasal nitric oxide production in PCD and (2) discovery of biallelic mutations in multiple PCD-causing genes. The use of these complementary diagnostic approaches shows that at least 30% of patients with PCD have normal ciliary ultrastructure. More accurate identification of patients with PCD has also allowed definition of a strong clinical phenotype, which includes neonatal respiratory distress in >80% of cases, daily nasal congestion and wet cough starting soon after birth, and early development of recurrent/chronic middle-ear and sinus disease. Recent studies, using advanced imaging and pulmonary physiologic assessments, clearly demonstrate early onset of lung disease in PCD, with abnormal air flow mechanics by age 6-8 years that is similar to cystic fibrosis, and age-dependent onset of bronchiectasis. The treatment of PCD is not standardized, and there are no validated PCD-specific therapies. Most patients with PCD receive suboptimal management, which should include airway clearance, regular surveillance of pulmonary function and respiratory microbiology, and use of antibiotics targeted to pathogens. The PCD Foundation is developing a network of clinical centers, which should improve diagnosis and management of PCD.

A complex of BBS1 and NPHP7 is required for cilia motility in zebrafish

Bardet-Biedl syndrome (BBS) and nephronophthisis (NPH) are hereditary autosomal recessive disorders, encoded by two families of diverse genes. BBS and NPH display several overlapping phenotypes including cystic kidney disease, retinitis pigmentosa, liver fibrosis, situs inversus and cerebellar defects. Since most of the BBS and NPH proteins localize to cilia and/or their appendages, BBS and NPH are considered ciliopathies. In this study, we characterized the function of the transcription factor Nphp7 in zebrafish, and addressed the molecular connection between BBS and NPH. The knockdown of zebrafish bbs1 and nphp7.2 caused similar phenotypic changes including convergent extension defects, curvature of the body axis, hydrocephalus, abnormal heart looping and cystic pronephros, all consistent with an altered ciliary function. Immunoprecipitation assays revealed a physical interaction between BBS1 and NPHP7, and the simultaneous knockdown of zbbs1 and znphp7.2 enhanced the cystic pronephros phenotype synergistically, suggesting a genetic interaction between zbbs1 and znphp7.2 in vivo. Deletion of zBbs1 or zNphp7.2 did not compromise cilia formation, but disrupted cilia motility. Although NPHP7 has been shown to act as transcriptional repressor, our studies suggest a crosstalk between BBS1 and NPHP7 in regulating normal function of the cilium.

Primary ciliary dyskinesia, an orphan disease

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disease, caused by specific primary structural and/or functional abnormalities of the motile cilia, in contrast with the transitory abnormalities seen in secondary ciliary dyskinesia. Disease-causing mutations in at least 16 genes have already been identified. The true incidence of PCD may be higher than currently reported, because the diagnosis is challenging and often missed. For the confirmation of PCD, both ciliary motility as well as ciliary ultrastructure must be evaluated. An early and adequate diagnosis and therapy can theoretically prevent bronchiectasis. Measurement of nasal nitric oxide has some value as a screening test but cannot be performed in young children. In the respiratory tract epithelium, impaired mucociliary clearance leads to chronic and/or recurrent upper and lower respiratory tract infections. In up to 75 % of the patients, respiratory manifestations start in the newborn period, although the diagnosis is often missed at that time. During embryogenesis, nodal cilia, which are motile cilia, determine the correct lateralization of the organs. Dysfunction of these cilia leads to random lateralization and thus situs inversus in approximately 50 % of the patients with PCD. The tail of a spermatozoon has a structure similar to that of a motile cilium. Consequently, male infertility due to immotile spermatozoa is often part of the characteristics of PCD. Given the heterogeneity and the rarity of the disorder, therapy is not evidence-based. Many treatment schedules are proposed in analogy with the treatment for cystic fibrosis.

CONCLUSION

Respiratory infections, situs inversus and male infertility are typical manifestations of PCD, a rare autosomal recessive disorder.

Primary ciliary dyskinesia: clinical criteria indicating ultrastructural studies

INTRODUCTION

Primary ciliary dyskinesia (PCD) is a congenital disease characterized by impaired ciliary function, which involves a wide range of symptoms that are mainly respiratory. Recent articles that base diagnosis on ciliary ultrastructural studies have estimated its prevalence to be 1/10,000 newborns, which is higher than previously thought. Our objective is to define criteria for clinical suspicion of DCP that would indicate ultrastructural studies, while optimizing these and providing early diagnoses.

METHODS

Ours is a descriptive, retrospective review of patients diagnosed with DCP in the Pediatric Pulmonology Unit at our hospital, from 1994 to 2010. The inclusion of cases was based on clinical suspicion criteria. Diagnosis was confirmed by characteristic ultrastructural changes observed in the electron microscopic study of the cilia.

RESULTS

Sixty-three samples were analyzed, and 34 cases of DCP and one case of acilia were confirmed. Mean age at diagnosis was 3.6 (range: 1 month to 19 years of age). The most frequent initial symptom was prolonged neonatal tachypnea in the newborns (20%) and lower respiratory tract episodes in the school-aged patients: recurrent pneumonia (46%), difficult-to-control asthma (26%), bronchiectasis (8.6%) and massive atelectasis (2.9%). Associated symptoms were present in 46% of the cases.

CONCLUSION

Our publication proposes the implementation of several clinical criteria depending on the age of presentation that would indicate the active search for alterations in the ciliary epithelium at reference centers.

Update of respiratory tract disease in children with primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a rare genetic disease characterized by abnormal ciliary structure and function leading to impaired mucociliary clearance and chronic progressive sinopulmonary disease. Upper and lower respiratory tract manifestations are cardinal features of PCD. This review summarizes the current state of knowledge of respiratory tract disease in individuals with PCD and highlights the challenges in identifying and quantifying lung disease in very young children with PCD. No specific therapies are available to correct ciliary dysfunction in PCD. Treatment is not evidence based, and recommendations are largely extrapolated from cystic fibrosis and other conditions with impaired mucociliary clearance. There is a pressing need to develop and validate outcome measures, including patient-reported outcomes, that could be used to evaluate potential therapies in PCD. This review concludes with recommendations for clinical endpoints and outcome measures and a prioritized list of treatments to study in PCD clinical trials.

Primary ciliary dyskinesia: evaluation using cilia beat frequency assessment via spectral analysis of digital microscopy images

Ciliary beat frequency (CBF) measurements provide valuable information for diagnosing of primary ciliary dyskinesia (PCD). We developed a system for measuring CBF, used it in association with electron microscopy to diagnose PCD, and then analyzed characteristics of PCD patients. The CBF measurement system was based on power spectra measured through digital imaging. Twenty-four patients suspected of having PCD (age 1-19 yr) were selected from a group of 75 children and adolescents with pneumopathies of unknown causes. Ten healthy, nonsmoking volunteers (age ≥ 17 yr) served as a control group. Nasal brush samples were collected, and CBF and electron microscopy were performed. PCD was diagnosed in 12 patients: 5 had radial spoke defects, 3 showed absent central microtubule pairs with transposition, 2 had outer dynein arm defects, 1 had a shortened outer dynein arm, and 1 had a normal ultrastructure. Previous studies have reported that the most common cilia defects are in the dynein arm. As expected, the mean CBF was higher in the control group (P < 0.001) and patients with normal ultrastructure (P < 0.002), than in those diagnosed with cilia ultrastructural defects (i.e., PCD patients). An obstructive ventilatory pattern was observed in 70% of the PCD patients who underwent pulmonary function tests. All PCD patients presented bronchial wall thickening on chest computed tomography scans. The protocol and diagnostic techniques employed allowed us to diagnose PCD in 16% of patients in this study.

Mechanisms of mammalian ciliary motility: Insights from primary ciliary dyskinesia genetics

Motile cilia and flagella are organelles that, historically, have been poorly understood and inadequately investigated. However, cilia play critical roles in fluid clearance in the respiratory system and the brain, and flagella are required for sperm motility. Genetic studies involving human patients and mouse models of primary ciliary dyskinesia over the last decade have uncovered a number of important ciliary proteins and have begun to elucidate the mechanisms underlying ciliary motility. When combined with genetic, biochemical, and cell biological studies in Chlamydomonas reinhardtii, these mammalian genetic analyses begin to reveal the mechanisms by which ciliary motility is regulated.

Primary ciliary dyskinesia in Amish communities

Primary ciliary dyskinesia is an autosomal recessive multigenic disease that results in impaired mucociliary clearance. We have diagnosed 9 subjects with primary ciliary dyskinesia from geographically dispersed Amish communities, on the basis of clinical characteristics and ciliary ultrastructural defects. Despite consanguinity, affected individuals had evidence of genetic heterogeneity.

Tubulin polyglutamylation is essential for airway ciliary function through the regulation of beating asymmetry

Airway epithelial cilia protect the mammalian respiratory system from harmful inhaled materials by providing the force necessary for effective mucociliary clearance. Ciliary beating is asymmetric, composed of clearly distinguished effective and recovery strokes. Neither the importance of nor the essential components responsible for the beating asymmetry has been directly elucidated. We report here that the beating asymmetry is crucial for ciliary function and requires tubulin glutamylation, a unique posttranslational modification that is highly abundant in cilia. WT murine tracheal cilia have an axoneme-intrinsic structural curvature that points in the direction of effective strokes. The axonemal curvature was lost in tracheal cilia from mice with knockout of a tubulin glutamylation-performing enzyme, tubulin tyrosine ligase-like protein 1. Along with the loss of axonemal curvature, the axonemes and tracheal epithelial cilia from these knockout (KO) mice lost beating asymmetry. The loss of beating asymmetry resulted in a reduction of cilia-generated fluid flow in trachea from the KO mice. The KO mice displayed a significant accumulation of mucus in the nasal cavity, and also emitted frequent coughing- or sneezing-like noises. Thus, the beating asymmetry is important for airway ciliary function. Our findings provide evidence that tubulin glutamylation is essential for ciliary function through the regulation of beating asymmetry, and provides insight into the molecular basis underlying the beating asymmetry.

Clinical and genetic aspects of primary ciliary dyskinesia/Kartagener syndrome

Primary ciliary dyskinesia is a genetically heterogeneous disorder of motile cilia. Most of the disease-causing mutations identified to date involve the heavy (dynein axonemal heavy chain 5) or intermediate(dynein axonemal intermediate chain 1) chain dynein genes in ciliary outer dynein arms, although a few mutations have been noted in other genes. Clinical molecular genetic testing for primary ciliary dyskinesia is available for the most common mutations. The respiratory manifestations of primary ciliary dyskinesia (chronic bronchitis leading to bronchiectasis, chronic rhino-sinusitis, and chronic otitis media)reflect impaired mucociliary clearance owing to defective axonemal structure. Ciliary ultrastructural analysis in most patients (>80%) reveals defective dynein arms, although defects in other axonemal components have also been observed. Approximately 50% of patients with primary ciliary dyskinesia have laterality defects (including situs inversus totalis and, less commonly, heterotaxy, and congenital heart disease),reflecting dysfunction of embryological nodal cilia. Male infertility is common and reflects defects in sperm tail axonemes. Most patients with primary ciliary dyskinesia have a history of neonatal respiratory distress, suggesting that motile cilia play a role in fluid clearance during the transition from a fetal to neonatal lung. Ciliopathies involving sensory cilia, including autosomal dominant or recessive polycystic kidney disease, Bardet-Biedl syndrome, and Alstrom syndrome, may have chronic respiratory symptoms and even bronchiectasis suggesting clinical overlap with primary ciliary dyskinesia.

Primary ciliary dyskinesia: improving the diagnostic approach

PURPOSE OF REVIEW

The diagnosis of primary ciliary dyskinesia (PCD) has relied on analysis of ciliary motility and ultrastructure; however, these tests are not readily available and have not been standardized. Consequently, the diagnosis of PCD may be delayed or missed or made incorrectly. This review outlines the potential utility of new diagnostic tests, including measurement of nasal nitric oxide production and systematic analysis for mutations in genes encoding ciliary proteins.

RECENT FINDINGS

Clinical manifestations of PCD have been expanded to include neonatal respiratory distress and heterotaxy. Measurement of nasal nitric oxide has emerged as a useful screening test for PCD based on the very low levels in PCD (approximately 1/10 of normal values). Genetic testing is emerging for PCD and demonstrates extensive genetic heterogeneity. Some genes and gene mutations involved in PCD have been defined. Approximately one-third of PCD cases have identifiable gene mutations in one of six different genes. An international effort is focused on defining PCD-causing defects in other genes.

SUMMARY

The incorporation of nasal nitric oxide measurement as a screening test to define probable PCD cases and gene mutation analysis to make a definitive diagnosis of PCD should enhance diagnostic evaluation of PCD.

Initiation and maturation of cilia-generated flow in newborn and postnatal mouse airway

Mucociliary clearance in the adult trachea is well characterized, but there are limited data in newborns. Cilia-generated flow was quantified across longitudinal sections of mouse trachea from birth through postnatal day (PND) 28 by tracking fluorescent microsphere speed and directionality. The percentage of ciliated tracheal epithelial cells, as determined by immunohistochemistry, was shown to increase linearly between PND 0 and PND 21 (R(2) = 0.94). While directionality measurements detected patches of flow starting at PND 3, uniform flow across the epithelia was not observed until PND 7 at a approximately 35% ciliated cell density. Flow became established at a maximal rate at PND 9 and beyond. A linear correlation was observed between the percentage of ciliated cells versus flow speed (R(2) = 0.495) and directionality (R(2) = 0.975) between PND 0 and PND 9. Cilia beat frequency (CBF) was higher at PND 0 than at all subsequent time points, but cilia beat waveform was not noticeably different. Tracheal epithelia from a mouse model of primary ciliary dyskinesia (PCD) harboring a Mdnah5 mutation showed that ciliated cell density was unaffected, but no cilia-generated flow was detected. Cilia in mutant airways were either immotile or with slow dyssynchronous beat and abnormal ciliary waveform. Overall, our studies showed that the initiation of cilia-generated flow is directly correlated with an increase in epithelial ciliation, with the measurement of directionality being more sensitive than speed for detecting flow. The higher CBF observed in newborn epithelia suggests unique physiology in the newborn trachea, indicating possible clinical relevance to the pathophysiology of respiratory distress seen in newborn PCD patients.

Evaluation of residual functional lung volume on Tc-99m DTPA aerosol ventilation and Tc-99m MAA perfusion scintigraphy in primary ciliary dyskinesia (Kartagener syndrome)

Kartagener syndrome is diagnosed as sinusitis, bronchitis (bronchiectasis), and situs inversus by the clinical features. It is a subclass of primary ciliary dyskinesia (PCD) disease. A 12-year-old girl who had frequent upper and lower airway infections since birth, which was confirmed as Kartagener syndrome by HRCT imaging. We present the residual functional lung volume and mucociliary clearance findings seen on Tc-99m DTPA aerosol ventilation and Tc-99m MAA perfusion scintigraphy.

Heterotaxy and complex structural heart defects in a mutant mouse model of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder associated with ciliary defects and situs inversus totalis, the complete mirror image reversal of internal organ situs (positioning). A variable incidence of heterotaxy, or irregular organ situs, also has been reported in PCD patients, but it is not known whether this is elicited by the PCD-causing genetic lesion. We studied a mouse model of PCD with a recessive mutation in Dnahc5, a dynein gene commonly mutated in PCD. Analysis of homozygous mutant embryos from 18 litters yielded 25% with normal organ situs, 35% with situs inversus totalis, and 40% with heterotaxy. Embryos with heterotaxy had complex structural heart defects that included discordant atrioventricular and ventricular outflow situs and atrial/pulmonary isomerisms. Variable combinations of a distinct set of cardiovascular anomalies were observed, including superior-inferior ventricles, great artery alignment defects, and interrupted inferior vena cava with azygos continuation. The surprisingly high incidence of heterotaxy led us to evaluate the diagnosis of PCD. PCD was confirmed by EM, which revealed missing outer dynein arms in the respiratory cilia. Ciliary dyskinesia was observed by videomicroscopy. These findings show that Dnahc5 is required for the specification of left-right asymmetry and suggest that the PCD-causing Dnahc5 mutation may also be associated with heterotaxy.

Genetic causes of bronchiectasis: primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder reflecting abnormalities in the structure and function of motile cilia and flagella, causing impairment of mucociliary clearance, left-right body asymmetry, and sperm motility. Clinical manifestations include respiratory distress in term neonates, recurrent otosinopulmonary infections, bronchiectasis, situs inversus and/or heterotaxy, and male infertility. Genetic discoveries are emerging from family-based linkage studies and from testing candidate genes. Mutations in 2 genes, DNAI1 and DNAH5, frequently cause PCD as an autosomal recessive disorder. A clinical genetic test has been recently established for DNAI1 and DNAH5, which involves sequencing 9 exons that harbor the most common mutations. This approach will identify at least one mutation in these 2 genes in approximately 25% of PCD patients. If biallelic mutations are identified, the test is diagnostic. If only one mutation is identified, the full gene may be sequenced to search for a trans-allelic mutation. As more disease-causing gene mutations are identified, broader genetic screening panels will further identify patients with PCD. Ongoing investigations are beginning to identify genetic mutations in novel clinical phenotypes for PCD, such as congenital heart disease and male infertility, and new associations are being established between 'ciliary' genetic mutations and clinical phenotypes.

Pseudo-asthma: when cough, wheezing, and dyspnea are not asthma

Although asthma is the most common cause of cough, wheeze, and dyspnea in children and adults, asthma is often attributed inappropriately to symptoms from other causes. Cough that is misdiagnosed as asthma can occur with pertussis, cystic fibrosis, primary ciliary dyskinesia, airway abnormalities such as tracheomalacia and bronchomalacia, chronic purulent or suppurative bronchitis in young children, and habit-cough syndrome. The respiratory sounds that occur with the upper airway obstruction caused by the various manifestations of the vocal cord dysfunction syndrome or the less common exercise-induced laryngomalacia are often mischaracterized as wheezing and attributed to asthma. The perception of dyspnea is a prominent symptom of hyperventilation attacks. This can occur in those with or without asthma, and patients with asthma may not readily distinguish the perceived dyspnea of a hyperventilation attack from the acute airway obstruction of asthma. Dyspnea on exertion, in the absence of other symptoms of asthma or an unequivocal response to albuterol, is most likely a result of other causes. Most common is the dyspnea associated with normal exercise limitation, but causes of dyspnea on exertion can include other physiologic abnormalities including exercise-induced vocal cord dysfunction, exercise-induced laryngomalacia, exercise-induced hyperventilation, and exercise-induced supraventricular tachycardia. A careful history, attention to the nature of the respiratory sounds that are present, spirometry, exercise testing, and blood-gas measurement provide useful data to sort out the various causes and avoid inappropriate treatment of these pseudo-asthma clinical manifestations.